ALKALI AND ALKALINE EARTH METALS
Group - 1 and 2 Elements:
General introduction, electronic configuration and general trends in physical and chemical properties of elements,
The alkali metals are the elements located in Group IA of the periodic table.
The alkali metals have many physical properties common to metals, but their densities are lower than those of other metals.
Alkali metals have one electron in their outer shell.
This gives them the largest atomic radii of the elements in their respective periods.
Their low ionization energies result in their metallic properties and high reactivities.
An alkali metal can easily lose its valence electron to form the univalent cation.
Alkali metals have low electronegativities.
They react readily with nonmetals, particularly halogens.
ALKALINE EARTH METALS
The six alkaline earth metals—beryllium, magnesium, calcium, strontium, barium, and radium—comprise Group 2 on the periodic table of elements.
They are in Group 2 beside the alkali metals in Group 1, and as their names suggest, the two families share a number of characteristics, most notably their high reactivity.
Magnesium and calcium have a number of uses, ranging from building and other structural applications to dietary supplements.
In fact, both are significant components in the metabolism of living things—including the human body.
Barium and beryllium have numerous specialized applications in areas from jewelry to medicine, while strontium is primarily used in fireworks.
Radium, has radioactive qualities.
Thursday, January 31, 2008
AIEEE Chemistry Unit 14C Compounds of Sodium
Preparation and properties of some important compounds - sodium carbonate, sodium chloride, sodium hydroxide and sodium hydrogen carbonate;
Sodium carbonate (Na2CO3)
Sodium carbonate exists as anhydrous (Na2CO3) and also as hydrated salt. The decahydrated salt (Na2CO3.10H2O) is known as washing soda while the anhydrous salt is called soda ash.
Occurrence
Large deposits of this salt occur in Owens lake in California and Lake Magadi in British East Africa. It occurs native as Na2CO3.NaHCO3.H2O in Egypt.
During hot weather, soda is also collected from a large number of alkaline lakes.
Manufacture of Sodium Carbonate
Ammonia-soda process (or Solvay process)
This process is the most popularly used method. As Ernest Solvay, the Belgian chemical engineer, devised it in 1864 it is known as Solvay process.
Raw materials
The raw materials for this process are common salt, ammonia and limestone (for supplying CO2 and quicklime).
Principle
When carbon dioxide is passed into a concentrated solution of brine saturated with ammonia, ammonium bicarbonate is produced,
The ammonium bicarbonate then reacts with common salt forming sodium bicarbonate,
Sodium bicarbonate being slightly soluble (in presence of sodium ions) gets precipitated. The precipitated sodium bicarbonate is removed by filtration and changed into sodium carbonate by heating.
The mother liquor remaining after the precipitation of sodium bicarbonate contains ammonium chloride. This is used to regenerate ammonia (one of the raw materials) by steam heating with milk of lime.
Lime is obtained by heating limestone.
Ammonia and carbon dioxide liberated are utilized in making the whole process cyclic and continuous. The only by-product in the process is calcium chloride.
Sodium chloride (NaCl)
Sodium chloride (NaCl) or common salt is an ionic crystal consisting of equal numbers of sodium and chlorine atoms and is an essential component in the human diet, being found in blood sweat and tears.
Occurrence
Sodium chloride is abundant and can be found naturally occurring. It can be found in the mineral halite (pure rock salt) as well as in mixed evaporates in salt lakes.
Sea water also contains 2.7% by weight salt and constitutes 80% of the dissolved minerals in sea water.
Production
Sodium chloride is mined or obtained from brine, when water is added to salt deposits.
Alternatively, it is obtained from sea water. This is commonly known as sea salt and constitutes most table salt. It also contains some impurities.
Sodium chloride:
• Has a cubic crystalline structure
• Is clear when pure, although may also appear white, grey or brownish, depending upon purity
• Is soluble in water
• Is slightly soluble in other liquids
• Is odourless
• Has a characteristic taste
• Molten sodium chloride is an electrical conductor
Symbol NaCl
Atomic Weight 58.44
Eutectic Composition 23.31% NaCl
Melting Point 801°C
Boiling Point 1465°C
Density 2.17g/cm3
Refractive Index 1.5442
Mohs Hardness 2.5
Co-Efficient of Thermal Expansion @ 0°C 40x10-6
Solubility g/100g H2O at 0°C 35.7
Sodium chloride is used for:
• Windows for analytical instruments
• De-icing
• Food and cooking
• High power lasers
• To produce chlorine and sodium
• Historically it has been used as a form of currency
Sodium hydroxide
sodium hydroxide chemical compound, NaOH, is a white crystalline substance that readily absorbs carbon dioxide and moisture from the air.
It is very soluble in water, alcohol, and glycerin.
It is a caustic and a strong base
It is commonly known as caustic soda, lye, or sodium hydrate.
The principal method for its manufacture is electrolytic dissociation of sodium chloride; chlorine gas is a coproduct.
Small amounts of sodium hydroxide are produced by the soda-lime process in which a concentrated solution of sodium carbonate (soda) is reacted with calcium hydroxide (slaked lime); calcium carbonate precipitates, leaving a sodium hydroxide solution.
The major use of sodium hydroxide is as a chemical and in the manufacture of other chemicals; because it is inexpensive, it is widely used wherever a strong base is needed.
It is also used in producing rayon and other textiles, in making paper, in etching aluminum, in making soaps and detergents, and in a wide variety of other uses.
Sodium Bicarbonate NaHCO-3
Sodium Bicarbonate, commonly called baking soda, is a white odourless, crystalline solid, completely soluble in water but slightly soluble in ethanol. It is the mildest of all sodium alkalis.
It is prepared from purified sodium carbonate or sodium hydroxide solution with passing carbon dioxide which is bubbled into the solution of pure carbonate, and the bicarbonate precipitates out to be dried as the bicarbonate is less soluble than the carbonate.
Sodium bicarbonate is also made as an intermediate product in the Solvay process (described above)which is to make sodium carbonate from calcium carbonate by treating sodium chloride with ammonia and carbon dioxide.
The major use of sodium bicarbonate is in baking powders.
Sodium Bicarbonate plays an important role in the products of many diverse industries with functions of releasing CO2 when heated above about 50 C or when reacted with a weak acid makes sodium bicarbonate a key ingredient in food leavening as well as in the manufacture of effervescent salts and beverages.
It can react as an acid or a base in water treatment.
In health and beauty applications, mild abrasivity and ability to reduce odors chemically by neutralizing the acid by-products of bacteria are utilized.
It is also used in treating wool and silk, fire extinguishers, pharmacy, leather, oredressing, metallurgy, in cleaning preparations and industrial & chemical processe.
Uses
food & food processing, beverages , pharmaceuticals , animal foodstuffs , household cleaning products , rubber & plastics foam blowing , fire extinguishers & explosion suppression , effluent & water treatment, flue gas treatment , oil drilling , industrial & chemical processes
Sodium carbonate (Na2CO3)
Sodium carbonate exists as anhydrous (Na2CO3) and also as hydrated salt. The decahydrated salt (Na2CO3.10H2O) is known as washing soda while the anhydrous salt is called soda ash.
Occurrence
Large deposits of this salt occur in Owens lake in California and Lake Magadi in British East Africa. It occurs native as Na2CO3.NaHCO3.H2O in Egypt.
During hot weather, soda is also collected from a large number of alkaline lakes.
Manufacture of Sodium Carbonate
Ammonia-soda process (or Solvay process)
This process is the most popularly used method. As Ernest Solvay, the Belgian chemical engineer, devised it in 1864 it is known as Solvay process.
Raw materials
The raw materials for this process are common salt, ammonia and limestone (for supplying CO2 and quicklime).
Principle
When carbon dioxide is passed into a concentrated solution of brine saturated with ammonia, ammonium bicarbonate is produced,
The ammonium bicarbonate then reacts with common salt forming sodium bicarbonate,
Sodium bicarbonate being slightly soluble (in presence of sodium ions) gets precipitated. The precipitated sodium bicarbonate is removed by filtration and changed into sodium carbonate by heating.
The mother liquor remaining after the precipitation of sodium bicarbonate contains ammonium chloride. This is used to regenerate ammonia (one of the raw materials) by steam heating with milk of lime.
Lime is obtained by heating limestone.
Ammonia and carbon dioxide liberated are utilized in making the whole process cyclic and continuous. The only by-product in the process is calcium chloride.
Sodium chloride (NaCl)
Sodium chloride (NaCl) or common salt is an ionic crystal consisting of equal numbers of sodium and chlorine atoms and is an essential component in the human diet, being found in blood sweat and tears.
Occurrence
Sodium chloride is abundant and can be found naturally occurring. It can be found in the mineral halite (pure rock salt) as well as in mixed evaporates in salt lakes.
Sea water also contains 2.7% by weight salt and constitutes 80% of the dissolved minerals in sea water.
Production
Sodium chloride is mined or obtained from brine, when water is added to salt deposits.
Alternatively, it is obtained from sea water. This is commonly known as sea salt and constitutes most table salt. It also contains some impurities.
Sodium chloride:
• Has a cubic crystalline structure
• Is clear when pure, although may also appear white, grey or brownish, depending upon purity
• Is soluble in water
• Is slightly soluble in other liquids
• Is odourless
• Has a characteristic taste
• Molten sodium chloride is an electrical conductor
Symbol NaCl
Atomic Weight 58.44
Eutectic Composition 23.31% NaCl
Melting Point 801°C
Boiling Point 1465°C
Density 2.17g/cm3
Refractive Index 1.5442
Mohs Hardness 2.5
Co-Efficient of Thermal Expansion @ 0°C 40x10-6
Solubility g/100g H2O at 0°C 35.7
Sodium chloride is used for:
• Windows for analytical instruments
• De-icing
• Food and cooking
• High power lasers
• To produce chlorine and sodium
• Historically it has been used as a form of currency
Sodium hydroxide
sodium hydroxide chemical compound, NaOH, is a white crystalline substance that readily absorbs carbon dioxide and moisture from the air.
It is very soluble in water, alcohol, and glycerin.
It is a caustic and a strong base
It is commonly known as caustic soda, lye, or sodium hydrate.
The principal method for its manufacture is electrolytic dissociation of sodium chloride; chlorine gas is a coproduct.
Small amounts of sodium hydroxide are produced by the soda-lime process in which a concentrated solution of sodium carbonate (soda) is reacted with calcium hydroxide (slaked lime); calcium carbonate precipitates, leaving a sodium hydroxide solution.
The major use of sodium hydroxide is as a chemical and in the manufacture of other chemicals; because it is inexpensive, it is widely used wherever a strong base is needed.
It is also used in producing rayon and other textiles, in making paper, in etching aluminum, in making soaps and detergents, and in a wide variety of other uses.
Sodium Bicarbonate NaHCO-3
Sodium Bicarbonate, commonly called baking soda, is a white odourless, crystalline solid, completely soluble in water but slightly soluble in ethanol. It is the mildest of all sodium alkalis.
It is prepared from purified sodium carbonate or sodium hydroxide solution with passing carbon dioxide which is bubbled into the solution of pure carbonate, and the bicarbonate precipitates out to be dried as the bicarbonate is less soluble than the carbonate.
Sodium bicarbonate is also made as an intermediate product in the Solvay process (described above)which is to make sodium carbonate from calcium carbonate by treating sodium chloride with ammonia and carbon dioxide.
The major use of sodium bicarbonate is in baking powders.
Sodium Bicarbonate plays an important role in the products of many diverse industries with functions of releasing CO2 when heated above about 50 C or when reacted with a weak acid makes sodium bicarbonate a key ingredient in food leavening as well as in the manufacture of effervescent salts and beverages.
It can react as an acid or a base in water treatment.
In health and beauty applications, mild abrasivity and ability to reduce odors chemically by neutralizing the acid by-products of bacteria are utilized.
It is also used in treating wool and silk, fire extinguishers, pharmacy, leather, oredressing, metallurgy, in cleaning preparations and industrial & chemical processe.
Uses
food & food processing, beverages , pharmaceuticals , animal foodstuffs , household cleaning products , rubber & plastics foam blowing , fire extinguishers & explosion suppression , effluent & water treatment, flue gas treatment , oil drilling , industrial & chemical processes
Thursday, January 24, 2008
AIEEE Chemistry Unit 15A P Block Elements
Group - 13 to Group 18 Elements
General Introduction: Electronic configuration and general trends in physical and chemical properties of elements across the periods and down the groups; unique behaviour of the first element in each group.
General Introduction: Electronic configuration and general trends in physical and chemical properties of elements across the periods and down the groups; unique behaviour of the first element in each group.
AIEEE Chemistry Unit 15B Group 13 Elements
Groupwise study of the p–block elements Group-13:
Preparation, properties and uses of boron and aluminium;
Structure, properties and uses of borax, boric acid, diborane, boron trifluoride, aluminium chloride and alums.
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Preparation, properties and uses of boron and aluminium;
Structure, properties and uses of borax, boric acid, diborane, boron trifluoride, aluminium chloride and alums.
-------------------
AIEEE Chemistry Unit 15C Group 14 Elements
Group - 14:
Tendency for catenation; Structure, properties and uses of allotropes and oxides of carbon, silicon tetrachloride, silicates, zeolites and silicones.
Tendency for catenation; Structure, properties and uses of allotropes and oxides of carbon, silicon tetrachloride, silicates, zeolites and silicones.
AIEEE Chemistry Unit 15D Group 15 Elements
Properties and uses of nitrogen a
nd phosphorus;
Allotrophic forms of phosphorus; Preparation, properties, structure and uses of ammonia, nitric acid, phosphine and phosphorus halides, (PCl3, PCl5);
Structures of oxides and oxoacids of nitrogen and phosphorus.
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nd phosphorus;
Allotrophic forms of phosphorus; Preparation, properties, structure and uses of ammonia, nitric acid, phosphine and phosphorus halides, (PCl3, PCl5);
Structures of oxides and oxoacids of nitrogen and phosphorus.
-----------------
AIEEE Chemistry Unit 15E Group 16 Elements
Group - 16:
Preparation, properties, structures and uses of dioxygen and ozone; Allotropic forms of sulphur; Preparation, properties, structures and uses of sulphur dioxide, sulphuric acid (including its industrial preparation); Structures of oxoacids of sulphur.
Preparation, properties, structures and uses of dioxygen and ozone; Allotropic forms of sulphur; Preparation, properties, structures and uses of sulphur dioxide, sulphuric acid (including its industrial preparation); Structures of oxoacids of sulphur.
AIEEE Chemistry Unit 15F Group 17 Elements
Group - 17:
Preparation, properties and uses of chlorine and hydrochloric acid; Trends in the acidic nature of hydrogen halides; Structures of Interhalogen compounds and oxides and oxoacids of halogens.
Preparation, properties and uses of chlorine and hydrochloric acid; Trends in the acidic nature of hydrogen halides; Structures of Interhalogen compounds and oxides and oxoacids of halogens.
AIEEE Chemistry Unit 15G Group 18 Elements
Occurrence and uses of noble gases; Structures of fluorides and oxides of xenon.
Helium
Neon
Argon
Helium
Neon
Argon
AIEEE Chemistry UNIT 16 d – and f – BLOCK ELEMENTS
Transition Elements :
General introduction, electronic configuration, occurrence and characteristics,
A transition element may be defined as an element which in its elementary form or in at least one of its oxidation states, possesses partially filled d orbitals in its penultimate shell.
The definition excludes zinc, cadmium, and mercury from the transition elements, however their properties are an extension of the properties of transition elements, they are generally considered along with transition elements.
Three series of elements are formed by filling the 3d, 4d, and 5d shells by electrons.
First series or 3d series: Scandium to Zinc
Second series or 4d series: Yitrium to cadmium
Third series or 5d series: Lanthanum to hafnium to mercury
Transition Metals
The ten elements from Scandium to Zinc form the first transition metal series. They closely resemble each other and are hard, dense, shiny metals with high melting and boiling points. They readily form alloys and have other properties in common. Crossing the period from Sc to Zn there is a small decrease in atomic radius and increase in electronegativity and ionisation energy. Most of the properties of transition metals are related to their electronic structures.
Electronic Structure
Transition elements are characterised by having a partially filled d sub-shell
Sc [Ar] 3d1 4s2
Ti [Ar] 3d2 4s2
V [Ar] 3d3 4s2
*Cr [Ar] 3d5 4s1
Mn [Ar] 3d5 4s2
Fe [Ar] 3d6 4s2
Co [Ar] 3d7 4s2
Ni [Ar] 3d8 4s2
*Cu [Ar] 3d10 4s1
Zn [Ar] 3d10 4s2
*Note that in Cr the arrangement [Ar] 3d5 4s1 with half-filled 3d and 4s sub-shells is more stable than [Ar] 3d4 4s2.
In Cu [Ar] 3d10 4s1 with a completely filled 3d sub-shell and a half-filled 4s sub-shell is more stable than [Ar] 3d9 4s2.
General characteristics
1. They are hard and brittle metals.
2. They have a high melting and boiling points and have higher heats of vaporization than non transition elements.
3. The transition elements have very high densities as compared to the metals of groups I and II (s-block).
4. The first ionization energies of d-block elements are higher than those of s-block elements but are less than those of p-block elements.
5. They are electropositive in nature.
6. Most of them form coloured compounds.
7. The have good tendency to form complexes.
8. They exhibit several oxidation states.
9. Their compounds are generally paramagnetic n nature.
10. They form alloys with other metals.
11. They form interstitial compound with elements such as hydrogen, boron, carbon, nitrogen etc.
12. Most of the transition metals such Mn, Ni, Co, Cr, V, Pt etc. and their compounds have been used as good catalysts.
Oxidation States
Transition metals form ions which are characterised by having a partially filled d sub-shell. In case of 3d series electrons in 4s as well as electrons in 3d participte in reactions. Lower oxidation states represent the participation of electrons in 4s only. Higher oxidation states result when electrons in 3d also participate.
The common oxidation states of various elements are:
Sc 3
---------------------------------------
Ti 2 3
-----------------------------------------
V 2 3 4 5
------------------------------------------
Cr (1) 2 3 (5) 6
-------------------------------------------------
Mn 2 3 4 (5) 6 7
-----------------------------------------
Fe 2 3 (4) (5) (6)
-----------------------------------------
Co 2 3 (4)
--------------------------------------------
Ni 2 3
-------------------------------------
Cu 1 2
----------------------------------
Zn 2
------------------------------
Oxidation states in brackets are unstable
Sc and Zn are not typical transition metals as they only have one oxidation state which does not have a partially filled d sub-shell. (Sc3+ [Ar], Zn2+ [Ar] 3d10).
Common oxidation states are +2 and +3, with the +2 state more common towards the end. The higher oxidation states are shown in compounds with electronegative elements like O, Cl or F (e.g. Cr2O7^2- [+6], MnO4^- [+7]).
Variable oxidation state is found because of the small difference in energy between the 3d and 4s sub-shells. This allows varying numbers of electrons to be used in bonding. When forming ions transition metals lose electrons from the 4s sub-shell before the 3d.
General introduction, electronic configuration, occurrence and characteristics,
A transition element may be defined as an element which in its elementary form or in at least one of its oxidation states, possesses partially filled d orbitals in its penultimate shell.
The definition excludes zinc, cadmium, and mercury from the transition elements, however their properties are an extension of the properties of transition elements, they are generally considered along with transition elements.
Three series of elements are formed by filling the 3d, 4d, and 5d shells by electrons.
First series or 3d series: Scandium to Zinc
Second series or 4d series: Yitrium to cadmium
Third series or 5d series: Lanthanum to hafnium to mercury
Transition Metals
The ten elements from Scandium to Zinc form the first transition metal series. They closely resemble each other and are hard, dense, shiny metals with high melting and boiling points. They readily form alloys and have other properties in common. Crossing the period from Sc to Zn there is a small decrease in atomic radius and increase in electronegativity and ionisation energy. Most of the properties of transition metals are related to their electronic structures.
Electronic Structure
Transition elements are characterised by having a partially filled d sub-shell
Sc [Ar] 3d1 4s2
Ti [Ar] 3d2 4s2
V [Ar] 3d3 4s2
*Cr [Ar] 3d5 4s1
Mn [Ar] 3d5 4s2
Fe [Ar] 3d6 4s2
Co [Ar] 3d7 4s2
Ni [Ar] 3d8 4s2
*Cu [Ar] 3d10 4s1
Zn [Ar] 3d10 4s2
*Note that in Cr the arrangement [Ar] 3d5 4s1 with half-filled 3d and 4s sub-shells is more stable than [Ar] 3d4 4s2.
In Cu [Ar] 3d10 4s1 with a completely filled 3d sub-shell and a half-filled 4s sub-shell is more stable than [Ar] 3d9 4s2.
General characteristics
1. They are hard and brittle metals.
2. They have a high melting and boiling points and have higher heats of vaporization than non transition elements.
3. The transition elements have very high densities as compared to the metals of groups I and II (s-block).
4. The first ionization energies of d-block elements are higher than those of s-block elements but are less than those of p-block elements.
5. They are electropositive in nature.
6. Most of them form coloured compounds.
7. The have good tendency to form complexes.
8. They exhibit several oxidation states.
9. Their compounds are generally paramagnetic n nature.
10. They form alloys with other metals.
11. They form interstitial compound with elements such as hydrogen, boron, carbon, nitrogen etc.
12. Most of the transition metals such Mn, Ni, Co, Cr, V, Pt etc. and their compounds have been used as good catalysts.
Oxidation States
Transition metals form ions which are characterised by having a partially filled d sub-shell. In case of 3d series electrons in 4s as well as electrons in 3d participte in reactions. Lower oxidation states represent the participation of electrons in 4s only. Higher oxidation states result when electrons in 3d also participate.
The common oxidation states of various elements are:
Sc 3
---------------------------------------
Ti 2 3
-----------------------------------------
V 2 3 4 5
------------------------------------------
Cr (1) 2 3 (5) 6
-------------------------------------------------
Mn 2 3 4 (5) 6 7
-----------------------------------------
Fe 2 3 (4) (5) (6)
-----------------------------------------
Co 2 3 (4)
--------------------------------------------
Ni 2 3
-------------------------------------
Cu 1 2
----------------------------------
Zn 2
------------------------------
Oxidation states in brackets are unstable
Sc and Zn are not typical transition metals as they only have one oxidation state which does not have a partially filled d sub-shell. (Sc3+ [Ar], Zn2+ [Ar] 3d10).
Common oxidation states are +2 and +3, with the +2 state more common towards the end. The higher oxidation states are shown in compounds with electronegative elements like O, Cl or F (e.g. Cr2O7^2- [+6], MnO4^- [+7]).
Variable oxidation state is found because of the small difference in energy between the 3d and 4s sub-shells. This allows varying numbers of electrons to be used in bonding. When forming ions transition metals lose electrons from the 4s sub-shell before the 3d.
AIEEE Chemistry Unit 16B First Row Transition Elements
Syllabus
general trends in properties of the first row transition elements - physical properties, ionization enthalpy, oxidation states, atomic radii, colour, catalytic behaviour, magnetic properties, complex formation, interstitial compounds, alloy formation;
general trends in properties of the first row transition elements - physical properties, ionization enthalpy, oxidation states, atomic radii, colour, catalytic behaviour, magnetic properties, complex formation, interstitial compounds, alloy formation;
AIEEE Chemistry Unit 16C K2Cr2O7 and KMnO4
Potassium Dichromate and Potassium Permanganate
Syllabus
Preparation, properties and uses of K2Cr2O7 and KMnO4.
Potassium dichromate
K2Cr2O7.
It's molecular weight is 294.19 g/mol.
Melting point: 3980C.
Boiling point: 5000C
Potassium dichromate's state at room temperature is solid.
Potassium dichromate is ionic.
It's molecular geometry is tetrahedral.
Potassium dichromate is crystalline ionic solid with a red-orange color.
It's uses include dyeing, staining, tanning leather, as bleach, oxidiser, depolariser for dry cells, etc.
Medically it has been used externally as an astringent, antiseptic, and caustic.
It has also been used in photographic screening.
It is used as an anti-pain remedy in homeopathy.
It is used ini ethonal determination.
When taken internally, it is a corrosive poison. Hence it is poisonous and hazardous to health.
Potassium Permanganate
KMnO4
Molecular Weight- 158.03 g
Melting Point- 270°C
Boiling Point- Doesn't boil
State - at room temperature solid - Purple, sweet flavor, and crystals.
Ionic
Uses- disinfectant, propellant in rockets, and is used in torpedos.
Syllabus
Preparation, properties and uses of K2Cr2O7 and KMnO4.
Potassium dichromate
K2Cr2O7.
It's molecular weight is 294.19 g/mol.
Melting point: 3980C.
Boiling point: 5000C
Potassium dichromate's state at room temperature is solid.
Potassium dichromate is ionic.
It's molecular geometry is tetrahedral.
Potassium dichromate is crystalline ionic solid with a red-orange color.
It's uses include dyeing, staining, tanning leather, as bleach, oxidiser, depolariser for dry cells, etc.
Medically it has been used externally as an astringent, antiseptic, and caustic.
It has also been used in photographic screening.
It is used as an anti-pain remedy in homeopathy.
It is used ini ethonal determination.
When taken internally, it is a corrosive poison. Hence it is poisonous and hazardous to health.
Potassium Permanganate
KMnO4
Molecular Weight- 158.03 g
Melting Point- 270°C
Boiling Point- Doesn't boil
State - at room temperature solid - Purple, sweet flavor, and crystals.
Ionic
Uses- disinfectant, propellant in rockets, and is used in torpedos.
AIEEE Chemistry Unit 16D - Inner Transition Elements
Syllabus
Inner Transition Elements :
Lanthanoids :
Electronic configuration, oxidation states, chemical reactivity and lanthanoid contraction.
Actinoids :
Electronic configuration and oxidation states.
Inner Transition Elements :
Lanthanoids :
Electronic configuration, oxidation states, chemical reactivity and lanthanoid contraction.
Actinoids :
Electronic configuration and oxidation states.
Tuesday, January 22, 2008
AIEEE Chemistry UNIT 17A CO-ORDINATION COMPOUNDS -I
Introduction to co-ordination compounds, Werner’s theory; ligands, co-ordination number, denticity, chelation; IUPAC nomenclature of mononuclear co-ordination compounds,
Coordination compounds are a special class of compounds in which the central metal atom is surrounded by ions or molecules beyond their valency.
There are also referred to as coordination complexes or complexes.
Haemoglobin, Chlrophyll, and vitamin B-12 are coordinatio compounds of iron, magnesium and cobalt respectively.
The interesting thing of coordination compound is that these are formed from apparently saturated molecules capable of independent existence.
Coordination compounds are a special class of compounds in which the central metal atom is surrounded by ions or molecules beyond their valency.
There are also referred to as coordination complexes or complexes.
Haemoglobin, Chlrophyll, and vitamin B-12 are coordinatio compounds of iron, magnesium and cobalt respectively.
The interesting thing of coordination compound is that these are formed from apparently saturated molecules capable of independent existence.
AIEEE Chemistry UNIT 17B CO-ORDINATION COMPOUNDS -II
isomerism;
Bonding-Valence bond approach and basic ideas of Crystal field theory, colour and magnetic properties; Importance of co-ordination compounds (in qualitative analysis, extraction of metals and in biological systems).
Bonding-Valence bond approach and basic ideas of Crystal field theory, colour and magnetic properties; Importance of co-ordination compounds (in qualitative analysis, extraction of metals and in biological systems).
AIEEE Chemistry UNIT 18 ENVIRONMENTAL CHEMISTRY
Syllabus
Environmental pollution: Atmospheric, water and soil.
Atmospheric pollution: Tropospheric and stratospheric
Tropospheric pollutants: Gaseous pollutants: Oxides of carbon, nitrogen and sulphur, hydrocarbons; their sources, harmful effects and prevention; Green house effect and Global warming; Acid rain;Particulate pollutants: Smoke, dust, smog, fumes, mist; their sources, harmful effects and prevention.
Stratospheric pollution: Formation and breakdown of ozone, depletion of ozone layer - its mechanism and effects.
websites
http://chemistry.about.com/od/environmentalchemistry/Environmental_Chemistry.htm
Environmental pollution: Atmospheric, water and soil.
Atmospheric pollution: Tropospheric and stratospheric
Tropospheric pollutants: Gaseous pollutants: Oxides of carbon, nitrogen and sulphur, hydrocarbons; their sources, harmful effects and prevention; Green house effect and Global warming; Acid rain;Particulate pollutants: Smoke, dust, smog, fumes, mist; their sources, harmful effects and prevention.
Stratospheric pollution: Formation and breakdown of ozone, depletion of ozone layer - its mechanism and effects.
websites
http://chemistry.about.com/od/environmentalchemistry/Environmental_Chemistry.htm
AIEEE Chemistry UNIT 18B Water and Soil Pollution
Syllabus
Water Pollution: Major pollutants such as, pathogens, organic wastes and chemical pollutants; their harmful effects and prevention.
Soil pollution: Major pollutants such as: Pesticides (insecticides,. herbicides and fungicides), their harmful effects and prevention.Strategies to control environmental pollution.
Hard water is any water containing an appreciable quantity of dissolved minerals. Soft water is treated water in which the only cation (positively charged ion) is sodium. The minerals in water give it a characteristic taste. Some natural mineral waters are highly sought for their flavor and the health benefits they may confer. Soft water, on the other hand, may taste salty and may not be suitable for drinking.
Water must be treated to remove undesirable substances before it can be distributed for domestic use. The type of treatments used is a function of the undesirable components that are present. Often it will be necessary to remove sediments, iron, mang anese, hardness (calcium and magnesium) and pathogenic bacteria. In the aeration process, air is pumped through the water to remove undesirable gases and volatile compounds. Iron and manganese are also precipitated in this stage. Addition of lime caused calcium and magnesium to precipitate out of solution. Coagulants are often used to remove colloids, algae and further clean the water. Carbon dioxide is then used to return the pH to near 7. Final treatment often involves addition of chlorine to disinfect the water by killing pathoghens.
Water Pollution: Major pollutants such as, pathogens, organic wastes and chemical pollutants; their harmful effects and prevention.
Soil pollution: Major pollutants such as: Pesticides (insecticides,. herbicides and fungicides), their harmful effects and prevention.Strategies to control environmental pollution.
Hard water is any water containing an appreciable quantity of dissolved minerals. Soft water is treated water in which the only cation (positively charged ion) is sodium. The minerals in water give it a characteristic taste. Some natural mineral waters are highly sought for their flavor and the health benefits they may confer. Soft water, on the other hand, may taste salty and may not be suitable for drinking.
Water must be treated to remove undesirable substances before it can be distributed for domestic use. The type of treatments used is a function of the undesirable components that are present. Often it will be necessary to remove sediments, iron, mang anese, hardness (calcium and magnesium) and pathogenic bacteria. In the aeration process, air is pumped through the water to remove undesirable gases and volatile compounds. Iron and manganese are also precipitated in this stage. Addition of lime caused calcium and magnesium to precipitate out of solution. Coagulants are often used to remove colloids, algae and further clean the water. Carbon dioxide is then used to return the pH to near 7. Final treatment often involves addition of chlorine to disinfect the water by killing pathoghens.
AIEEE Organic Chemistry UNIT 19A Purification and Characterisation of Organic Compounds
Syllabus
Purification (crystallization, sublimation, distillation, differential extraction, chromatography- principles and their applications).
Material to be developed and posted
Remaining portion in 19B
http://aieee-chemistry.blogspot.com/2008/01/aieee-organic-chemistry-unit-19b.html
Purification (crystallization, sublimation, distillation, differential extraction, chromatography- principles and their applications).
Material to be developed and posted
Remaining portion in 19B
http://aieee-chemistry.blogspot.com/2008/01/aieee-organic-chemistry-unit-19b.html
AIEEE Organic Chemistry UNIT 19B Qualitative and Quantitative Analysis
Syllabus
Qualitative analysis - detection of nitrogen, sulphur, phosphorus and halogens.
Quantitative analysis (basic principles only) – estimation of carbon, hydrogen, nitrogen, halogens, sulphur, phosphorus(basic principles only)
Calculations of empirical formula and molecular formula.
Numerical problems in organic quantitative analysis.
-------------------
Detection of Elements (N,S, halogens)
Lassaigne test is used for this.
First sodium extract of the given organic compound is prepared.
A pea sized dry piece of sodium metal (freshly cut) is taken in an ignition tube and the tube is heated to melt the sodium metal piece to shining globule. Then a pinch of the organic compound is introduced in the tube. Then the tube is further heated first gently and strongly till the lower end of the tube becomes red hot. The tube is then plunged and broken in about 20 ml. of distilled water taken in porcelain dish. The solution is boiled for about 5 minutes and filtered. The filtrate obtained is known as sodium extract.
Test for Nitrogen
To 2ml of sodium extract, a little ferrous sulphate is added. The solution is boiled and a little dilute sulphuric acid is added. Appearance of prussian blue or green colouration indicates the presence of nitrogen in the compound.
Acetic acid and lead acetate are used for detecting sulphur and NH4OH is used for detecting halogens.
Qualitative analysis - detection of nitrogen, sulphur, phosphorus and halogens.
Quantitative analysis (basic principles only) – estimation of carbon, hydrogen, nitrogen, halogens, sulphur, phosphorus(basic principles only)
Calculations of empirical formula and molecular formula.
Numerical problems in organic quantitative analysis.
-------------------
Detection of Elements (N,S, halogens)
Lassaigne test is used for this.
First sodium extract of the given organic compound is prepared.
A pea sized dry piece of sodium metal (freshly cut) is taken in an ignition tube and the tube is heated to melt the sodium metal piece to shining globule. Then a pinch of the organic compound is introduced in the tube. Then the tube is further heated first gently and strongly till the lower end of the tube becomes red hot. The tube is then plunged and broken in about 20 ml. of distilled water taken in porcelain dish. The solution is boiled for about 5 minutes and filtered. The filtrate obtained is known as sodium extract.
Test for Nitrogen
To 2ml of sodium extract, a little ferrous sulphate is added. The solution is boiled and a little dilute sulphuric acid is added. Appearance of prussian blue or green colouration indicates the presence of nitrogen in the compound.
Acetic acid and lead acetate are used for detecting sulphur and NH4OH is used for detecting halogens.
AIEEE Chemistry UNIT 20 SOME BASIC PRINCIPLES OF ORGANIC CHEMISTRY
Tetravalency of carbon;
Shapes of simple molecules - hybridization (s and p);
Classification of organic compounds based on functional groups: - C = C - , - C ? C - and those containing halogens, oxygen, nitrogen and sulphur; Homologous series; Isomerism - structural and stereoisomerism.
Nomenclature (Trivial and IUPAC)
Covalent bond fission: Homolytic and heterolytic: free radicals, carbocations and carbanions; stability of carbocations and free radicals, electrophiles and nucleophiles.
Electronic displacement in a covalent bond: Inductive effect, electromeric effect, resonance and hyperconjugation.
Common types of organic reactions - Substitution, addition, elimination and rearrangement.
-----------------
Hybridization of carbon
sp - in alkynes - triple bond
sp2 - in alkenes - double bond
sp3 - in alkanes
sigma and pi bonds
alkanes - all sigma bonds with hydrogen atoms or single bonds with carbon atoms
alkenes - one sigma and one pi bond in double bond, and all sigma bonds with hydrogen atoms or single bonds with carbon atoms
alkynes - one sigma and two pi bonds in triple bond, and all sigma bonds with hydrogen atoms or single bonds with carbon atoms
To be expanded
Isomerism
Nomenclature
Covalent bond
are in following blogs
Shapes of simple molecules - hybridization (s and p);
Classification of organic compounds based on functional groups: - C = C - , - C ? C - and those containing halogens, oxygen, nitrogen and sulphur; Homologous series; Isomerism - structural and stereoisomerism.
Nomenclature (Trivial and IUPAC)
Covalent bond fission: Homolytic and heterolytic: free radicals, carbocations and carbanions; stability of carbocations and free radicals, electrophiles and nucleophiles.
Electronic displacement in a covalent bond: Inductive effect, electromeric effect, resonance and hyperconjugation.
Common types of organic reactions - Substitution, addition, elimination and rearrangement.
-----------------
Hybridization of carbon
sp - in alkynes - triple bond
sp2 - in alkenes - double bond
sp3 - in alkanes
sigma and pi bonds
alkanes - all sigma bonds with hydrogen atoms or single bonds with carbon atoms
alkenes - one sigma and one pi bond in double bond, and all sigma bonds with hydrogen atoms or single bonds with carbon atoms
alkynes - one sigma and two pi bonds in triple bond, and all sigma bonds with hydrogen atoms or single bonds with carbon atoms
To be expanded
Isomerism
Nomenclature
Covalent bond
are in following blogs
AIEEE Chemistry UNIT 20A PRINCIPLES OF ORGANIC CHEMISTRY
Isomerism
The existence of two or more compounds with same molecular formula but different properties (physical, chemical or both) is known as isomerism; and the compounds themselves are called isomers.
Isomerism types:
i) Chain, nuclear or skeleton isomerism
This type of isomerism is due to the difference in the nature of the carbon chain (i.e. straight or branched) which forms the nucleus of the molecule,
ii) Position isomerism
It is due to the difference in the position of the substituent atom or group or an unsaturated linkage in the same carbon chain.
iii) Functional isomerism
This type of isomerism is due to difference in the nature of functional group present in the isomers,
iv) Metamerism
It is due to the difference in nature of alkyl groups attached to the same functional group. This type of isomerism is shown by compounds of the same homologous series.
v) Tautomerism
Tautomerism may be defined as the phenomenon in which a single compound exists in two readily interconvertible structures that differ markedly in the relative position of at least one atomic nucleus, generally hydrogen. The two different structures are known as tautomers of each other.
Stereo isomerism
When isomers have the same structural formula but differ in relative arrangement of atoms or groups in space within the molecule, these are known as stereoisomers and the phenomenon as stereoisomerism. The spatial arrangement of atoms or groups is also referred to as configuration of the molecule and thus we can say that the stereoisomers have the same structural formula but different configuration. Stereoisomerism is of two types.
(i) Geometrical isomerism
The isomers which possess the same structural formula but differ in the spatial arrangement of the groups around the double bond are known as geometrical isomers and the phenomenon is known as geometrical isomerism.
ii) Optical isomerism
This type of isomerism arises from different arrangements of atoms or groups in three dimensional space resulting in two isomers which are mirror image of each other. Optical isomers contain an asymmetric (chiral) carbon atom ( a carbon atom attached to four different atoms or groups) in their molecules.
The existence of two or more compounds with same molecular formula but different properties (physical, chemical or both) is known as isomerism; and the compounds themselves are called isomers.
Isomerism types:
i) Chain, nuclear or skeleton isomerism
This type of isomerism is due to the difference in the nature of the carbon chain (i.e. straight or branched) which forms the nucleus of the molecule,
ii) Position isomerism
It is due to the difference in the position of the substituent atom or group or an unsaturated linkage in the same carbon chain.
iii) Functional isomerism
This type of isomerism is due to difference in the nature of functional group present in the isomers,
iv) Metamerism
It is due to the difference in nature of alkyl groups attached to the same functional group. This type of isomerism is shown by compounds of the same homologous series.
v) Tautomerism
Tautomerism may be defined as the phenomenon in which a single compound exists in two readily interconvertible structures that differ markedly in the relative position of at least one atomic nucleus, generally hydrogen. The two different structures are known as tautomers of each other.
Stereo isomerism
When isomers have the same structural formula but differ in relative arrangement of atoms or groups in space within the molecule, these are known as stereoisomers and the phenomenon as stereoisomerism. The spatial arrangement of atoms or groups is also referred to as configuration of the molecule and thus we can say that the stereoisomers have the same structural formula but different configuration. Stereoisomerism is of two types.
(i) Geometrical isomerism
The isomers which possess the same structural formula but differ in the spatial arrangement of the groups around the double bond are known as geometrical isomers and the phenomenon is known as geometrical isomerism.
ii) Optical isomerism
This type of isomerism arises from different arrangements of atoms or groups in three dimensional space resulting in two isomers which are mirror image of each other. Optical isomers contain an asymmetric (chiral) carbon atom ( a carbon atom attached to four different atoms or groups) in their molecules.
AIEEE Chemistry UNIT 20B BASIC PRINCIPLES OF ORGANIC CHEMISTRY
Nomenclature (Trivial and IUPAC)
------------------
The longest possible chain is numbered from one side to the other by Arabic numerals, the direction being so chosen as to given the lowest numbers possible to the side chains. When series of locants containing the same number of terms are compared term by term, that series is “lowest” which contains the lowest number on the occasion of the first difference (Lowest sum rule). This rule is applied irrespective of the nature of the side chains.
Univalent branched radicals derived from hydrocarbon are named by prefixing the designation of the side chains to the name of the unbranched alkyl radical containing the LPCC starting from the carbon atom with the free valence, this atom being numbered as 1.
If two or more side chains of different nature are present, they are cited in alphabetical order and decided as follows
(i) The names of simple radicals are first alphabetized and the multiplying prefixes are then inserted.
Ethyl is cited before methyl, thus 4-Ethyl-3, 3-dimethylheptane
ii) The name of a complex radical is considered to start with the first letter of its complete name.
(iii) In cases where names of complex radicals are composed of identical words, preference for citation is given to that radical which contains the lowest locant at the first cited point of difference in the radical.
To be expanded
------------------
The longest possible chain is numbered from one side to the other by Arabic numerals, the direction being so chosen as to given the lowest numbers possible to the side chains. When series of locants containing the same number of terms are compared term by term, that series is “lowest” which contains the lowest number on the occasion of the first difference (Lowest sum rule). This rule is applied irrespective of the nature of the side chains.
Univalent branched radicals derived from hydrocarbon are named by prefixing the designation of the side chains to the name of the unbranched alkyl radical containing the LPCC starting from the carbon atom with the free valence, this atom being numbered as 1.
If two or more side chains of different nature are present, they are cited in alphabetical order and decided as follows
(i) The names of simple radicals are first alphabetized and the multiplying prefixes are then inserted.
Ethyl is cited before methyl, thus 4-Ethyl-3, 3-dimethylheptane
ii) The name of a complex radical is considered to start with the first letter of its complete name.
(iii) In cases where names of complex radicals are composed of identical words, preference for citation is given to that radical which contains the lowest locant at the first cited point of difference in the radical.
To be expanded
AIEEE Chemistry UNIT 20C SOME BASIC PRINCIPLES OF ORGANIC CHEMISTRY
Covalent Bond Fission
Syllabus 2008
Tetravalency of carbon; Shapes of simple molecules - hybridization (s and p); Classification of organic compounds based on functional groups: - C = C - , - C ? C - and those containing halogens, oxygen, nitrogen and sulphur; Homologous series; Isomerism - structural and stereoisomerism.
Nomenclature (Trivial and IUPAC)
Covalent bond fission: Homolytic and heterolytic: free radicals, carbocations and carbanions; stability of carbocations and free radicals, electrophiles and nucleophiles.
Electronic displacement in a covalent bond: Inductive effect, electromeric effect, resonance and hyperconjugation.
Common types of organic reactions - Substitution, addition, elimination and rearrangement.
----------------
Bond fission.
Bond breaking is also known as bond fission.
1. Homolytic fission
2. Heterolytic fission
----------------
Heterolytic fission results in the formation of two different chemical species in the sense that one is a cation and the other an anion. Homolytic fission results in two electrically uncharged radicals.
Reaction Intermediates
The species produced during cleavage of bonds are called reaction intermediates. The important ones are:
1. Free radical: A free radical is an atom or group of atoms having an unpaired electron. Thee are produced during the homolytic fission of a covalent bond.
2. carbocation: It is a group of atoms which contain positively charged carbon having only six electrons. It is obtained by heterolytic fission of covalent bond involving carbon atoms.
3. Carbanion: It is a species containing a carbon atom carrying a negative charge. They are generated during heterolytic fission of covalent bonds containing carbon, when an atom linked to carbon goes without the bonding electrons.
4. carbene: The carbenes are reactive neutral species in which the carbon atom has six electrons in the valence shell out of which two are shared. The simplest carbene is methylene (:CH2). It is formed wbehg diazomethan is decomposed by the action of light.
CH2N2 --> :CH2 + N2
Types of attacing reagents
1. Free radicals
2. Electrophiles
3. Nucleophiles
Typesof organic reactions
1. substitution reactions
2. Addition reactions
3. Elimination reactions
--i) α-Elimination
--ii) β-Elimination
--iii)γ-Elimination
4. Rearrangement reactions
5. Condensation reactions
6. Isomerism reactions
Syllabus 2008
Tetravalency of carbon; Shapes of simple molecules - hybridization (s and p); Classification of organic compounds based on functional groups: - C = C - , - C ? C - and those containing halogens, oxygen, nitrogen and sulphur; Homologous series; Isomerism - structural and stereoisomerism.
Nomenclature (Trivial and IUPAC)
Covalent bond fission: Homolytic and heterolytic: free radicals, carbocations and carbanions; stability of carbocations and free radicals, electrophiles and nucleophiles.
Electronic displacement in a covalent bond: Inductive effect, electromeric effect, resonance and hyperconjugation.
Common types of organic reactions - Substitution, addition, elimination and rearrangement.
----------------
Bond fission.
Bond breaking is also known as bond fission.
1. Homolytic fission
2. Heterolytic fission
----------------
Heterolytic fission results in the formation of two different chemical species in the sense that one is a cation and the other an anion. Homolytic fission results in two electrically uncharged radicals.
Reaction Intermediates
The species produced during cleavage of bonds are called reaction intermediates. The important ones are:
1. Free radical: A free radical is an atom or group of atoms having an unpaired electron. Thee are produced during the homolytic fission of a covalent bond.
2. carbocation: It is a group of atoms which contain positively charged carbon having only six electrons. It is obtained by heterolytic fission of covalent bond involving carbon atoms.
3. Carbanion: It is a species containing a carbon atom carrying a negative charge. They are generated during heterolytic fission of covalent bonds containing carbon, when an atom linked to carbon goes without the bonding electrons.
4. carbene: The carbenes are reactive neutral species in which the carbon atom has six electrons in the valence shell out of which two are shared. The simplest carbene is methylene (:CH2). It is formed wbehg diazomethan is decomposed by the action of light.
CH2N2 --> :CH2 + N2
Types of attacing reagents
1. Free radicals
2. Electrophiles
3. Nucleophiles
Typesof organic reactions
1. substitution reactions
2. Addition reactions
3. Elimination reactions
--i) α-Elimination
--ii) β-Elimination
--iii)γ-Elimination
4. Rearrangement reactions
5. Condensation reactions
6. Isomerism reactions
Monday, January 21, 2008
AIEEE Chemistry UNIT 21 HYDROCARBONS
Classification, isomerism, IUPAC nomenclature, general methods of preparation, properties and reactions:
Alkanes - Conformations: Sawhorse and Newman projections (of ethane); Mechanism of halogenation of alkanes.
Alkenes - Geometrical isomerism; Mechanism of electrophilic addition: addition of hydrogen, halogens, water, hydrogen halides (Markownikoff’s and peroxide effect); Ozonolysis, oxidation, and polymerization.
Alkynes - Acidic character; Addition of hydrogen, halogens, water and hydrogen halides; Polymerization.
Aromatic hydrocarbons - Nomenclature, benzene - structure and aromaticity; Mechanism of electrophilic substitution: halogenation, nitration, Friedel – Craft’s alkylation and acylation, directive influence of functional group in mono-substituted benzene.
Alkanes:
Introduction
Alkanes are saturated hydrocarbons containing only carbon-carbon single bonds in their molecules.
Thye are also called paraffins (meaning little affinity or reactivity, we will see later why it is so).
Alkanes are divided into 1. Open chain or acyclic Alkanes and 2. CycloAlkanes or cyclic alkanes.
Nomenclature of alkanes
Examples:
2,2-Dimethylpropane
2-Methylpentane
3-Methylhexane
3-ehtyl-2-methylhexane
4-ehtyl-2,4-dimethylhexane
4-(1-methyl ethyl) heptane or 4-Isopropylheptane
Straight chain alkanes or normal alkanes (n-alkanes): All the carbon atoms are attached by covalent bonds in a continuous chain.
Branched alkanes:
Iso-alkanes: In these, one carbon chain is attached to the second carbon atom of the long chain (parent chain).
Neo-alkanes: In these two single carbon branches are attached to the second carbon atom of the long chain.
Preparation of alkanes
General methods
1. From unsaturated hydrocarbons (alkenes and alkynes)
2. From alkyl halides
3. From carboxylic acids and their salts
1. From unsaturated hydrocarbons (alkenes and alkynes)
By catalytic hydrogenation alkenes and alkynes are converted into alkanes (Note that this point will come in alkenes and alkynes chapter as reactions of them).
Ni, Pt or Pd in the form of fine powder are used as catalysts. A temperature of 523-573 K needs to be employed.
Methane cannot be prepared by this method because alkenes or alkynes will have two carbons at their lowest level.
2. From alkyl halides
a) Wurtz reaction (specially in syllabus)
When an alkyl halide (usually bromide or iodide) is treated with sodium in dry ether, a symmetrical alkane containing both twice the number of carbon atoms of alkyl halide is obtained. The equation of the reaction will make the statement more clear.
RX + 2Na + XR ---> R-R + 2NaX catalyst sodium in dry ether
In the reaction different alkyl halides can also be used in stead of a single halide. If two different halides are taken with the aim of preparing an alkane with odd number of carbon atoms, a mixture of products is obtained in stead of a single alkane. This is because in this case three reactions takes place and three different products are obtained.
b) Reduction of alkyl halides
Reducing agents can be used to add hydrogen to the halide and remove the halogen atom.
i) Zinc + HCl is one reducing agent.
ii) Catalytic hydrogenation using Pd or Pt as catalyst
iii) Hydrogen iodide (halogen acid) in the presence of red phosphorous also acts as reducing agent. In this reaction phosphorous combines with iodine to form phosphorous triiodide.
iv) zinc copper couple and alcohol
c) By the use of Grignard reagent
Alkyl halides react with magnesium metal in diethyl ether to form alkyl magnesium halides which are called as Grignard reagents. (This reaction will come in alkyl halides chapter also)
Grignard reagetns are highly reactive and are easily decomposed by water or alcohol to form alkanes
RMgX + HOH (H2O) ---> RH + Mg(OH)X
3. From carboxylic acids and their salts
a) Decarboxylation reaction
b) Kolbe's reaction
c) Reduction of carboxylic acid
a) Decarboxylation reaction
When sodium salt of a monocarboxylic acid is heated with soda lime (amixture of NaOH and Cao in the ratio of 3:1) at about 630 K, alkane is formed.
RCOONa + NaOH -->RH + Na2CO3
In this reaction a CO2 group is removed from carboxylic acid and therefore the reaction is called decarboxylation.
b) Kolbe's reaction
When an acqueous solution of sodium or potassium salt of carboxylic acid is eletrolysed alkane is evolved at the anode.
Kolbe's reaction can also be used like wurtz reaction for preparing alkanes with even number of carbon atoms.
c) Reduction of carboxylic acid
Carboxylic acids are reduced to alkanes by hydroiodic acid (HI). In this reaction COOH group in the carboxylic acid is reduced to CH3 group.
The methods in this section can be summarised as
R-COONa ---> RH
R-COONa ---> R-R
R-COOH---> R-CH3
Industrial method: Petroleum provides the natural source of alkanes.
Physical properties of alkanes
1. State
2. Boiling point
3. Melting point
4. Solubility
5. Density
Chemical properties or reactions
1. Substitution reactions of alkanes
2. Oxidation
3. Action of steam
4. Isomerisation
5. Aromatization
6. Thermal decomposition or fragmentation
Alkanes - Conformations: Sawhorse and Newman projections (of ethane); Mechanism of halogenation of alkanes.
Alkenes - Geometrical isomerism; Mechanism of electrophilic addition: addition of hydrogen, halogens, water, hydrogen halides (Markownikoff’s and peroxide effect); Ozonolysis, oxidation, and polymerization.
Alkynes - Acidic character; Addition of hydrogen, halogens, water and hydrogen halides; Polymerization.
Aromatic hydrocarbons - Nomenclature, benzene - structure and aromaticity; Mechanism of electrophilic substitution: halogenation, nitration, Friedel – Craft’s alkylation and acylation, directive influence of functional group in mono-substituted benzene.
Alkanes:
Introduction
Alkanes are saturated hydrocarbons containing only carbon-carbon single bonds in their molecules.
Thye are also called paraffins (meaning little affinity or reactivity, we will see later why it is so).
Alkanes are divided into 1. Open chain or acyclic Alkanes and 2. CycloAlkanes or cyclic alkanes.
Nomenclature of alkanes
Examples:
2,2-Dimethylpropane
2-Methylpentane
3-Methylhexane
3-ehtyl-2-methylhexane
4-ehtyl-2,4-dimethylhexane
4-(1-methyl ethyl) heptane or 4-Isopropylheptane
Straight chain alkanes or normal alkanes (n-alkanes): All the carbon atoms are attached by covalent bonds in a continuous chain.
Branched alkanes:
Iso-alkanes: In these, one carbon chain is attached to the second carbon atom of the long chain (parent chain).
Neo-alkanes: In these two single carbon branches are attached to the second carbon atom of the long chain.
Preparation of alkanes
General methods
1. From unsaturated hydrocarbons (alkenes and alkynes)
2. From alkyl halides
3. From carboxylic acids and their salts
1. From unsaturated hydrocarbons (alkenes and alkynes)
By catalytic hydrogenation alkenes and alkynes are converted into alkanes (Note that this point will come in alkenes and alkynes chapter as reactions of them).
Ni, Pt or Pd in the form of fine powder are used as catalysts. A temperature of 523-573 K needs to be employed.
Methane cannot be prepared by this method because alkenes or alkynes will have two carbons at their lowest level.
2. From alkyl halides
a) Wurtz reaction (specially in syllabus)
When an alkyl halide (usually bromide or iodide) is treated with sodium in dry ether, a symmetrical alkane containing both twice the number of carbon atoms of alkyl halide is obtained. The equation of the reaction will make the statement more clear.
RX + 2Na + XR ---> R-R + 2NaX catalyst sodium in dry ether
In the reaction different alkyl halides can also be used in stead of a single halide. If two different halides are taken with the aim of preparing an alkane with odd number of carbon atoms, a mixture of products is obtained in stead of a single alkane. This is because in this case three reactions takes place and three different products are obtained.
b) Reduction of alkyl halides
Reducing agents can be used to add hydrogen to the halide and remove the halogen atom.
i) Zinc + HCl is one reducing agent.
ii) Catalytic hydrogenation using Pd or Pt as catalyst
iii) Hydrogen iodide (halogen acid) in the presence of red phosphorous also acts as reducing agent. In this reaction phosphorous combines with iodine to form phosphorous triiodide.
iv) zinc copper couple and alcohol
c) By the use of Grignard reagent
Alkyl halides react with magnesium metal in diethyl ether to form alkyl magnesium halides which are called as Grignard reagents. (This reaction will come in alkyl halides chapter also)
Grignard reagetns are highly reactive and are easily decomposed by water or alcohol to form alkanes
RMgX + HOH (H2O) ---> RH + Mg(OH)X
3. From carboxylic acids and their salts
a) Decarboxylation reaction
b) Kolbe's reaction
c) Reduction of carboxylic acid
a) Decarboxylation reaction
When sodium salt of a monocarboxylic acid is heated with soda lime (amixture of NaOH and Cao in the ratio of 3:1) at about 630 K, alkane is formed.
RCOONa + NaOH -->RH + Na2CO3
In this reaction a CO2 group is removed from carboxylic acid and therefore the reaction is called decarboxylation.
b) Kolbe's reaction
When an acqueous solution of sodium or potassium salt of carboxylic acid is eletrolysed alkane is evolved at the anode.
Kolbe's reaction can also be used like wurtz reaction for preparing alkanes with even number of carbon atoms.
c) Reduction of carboxylic acid
Carboxylic acids are reduced to alkanes by hydroiodic acid (HI). In this reaction COOH group in the carboxylic acid is reduced to CH3 group.
The methods in this section can be summarised as
R-COONa ---> RH
R-COONa ---> R-R
R-COOH---> R-CH3
Industrial method: Petroleum provides the natural source of alkanes.
Physical properties of alkanes
1. State
2. Boiling point
3. Melting point
4. Solubility
5. Density
Chemical properties or reactions
1. Substitution reactions of alkanes
2. Oxidation
3. Action of steam
4. Isomerisation
5. Aromatization
6. Thermal decomposition or fragmentation
AIEEE Chemistry UNIT 22 ORGANIC COMPOUNDS CONTAINING HALOGENS
General methods of preparation, properties and reactions; Nature of C-X bond; Mechanisms of substitution reactions.
Uses; Environmental effects of chloroform, iodoform, freons and DDT.
When hydrogen atom or atoms of alkanes are replaced by the corresponding number of halogen atoms, the compounds are called halogen derivatives of alkanes.
They are classified according to the number of halogen atoms that replace hydrogen atoms in the alkane.
Monohalogen derivatives: They contain only one halogen atom.
e.g. CH-3Cl Methyl chloride
CH-3-CH-CH-3 2-Bromopropane
!
Br
Monohalogen derivatives of alkane are called alkyl halides
Dihalogen alkanes contain two halogen atoms.
Trihalog alkanes contain three halogen atoms.
Monohalo alkanes
The general formula is RX where is a alkyl group and X is a halogen.
Classification of Haloalkanes
A. Type of halogen atoms; Fluorides, chlorides, bromides, iodides
B. Number of halogena atoms, monohalo, dihalo, trihalo, tetra halo.
Classification of Haloalkanes
1. Compounds containing sp3 hybridization
2. Compounds containing sp2 hybridization
Compounds containing sp3 hybridization
a) halo alkances or alkyl halides
(i)Primary halogenoalkanes
In a primary (1°) halogenoalkane, the carbon which carries the halogen atom is only attached to one other alkyl group.
Secondary halogenoalkanes
In a secondary (2°) halogenoalkane, the carbon with the halogen attached is joined directly to two other alkyl groups, which may be the same or different.
Tertiary halogenoalkanes
In a tertiary (3°) halogenoalkane, the carbon atom holding the halogen is attached directly to three alkyl groups, which may be any combination of same or different.
b) Allylic halides: Halogens attached to alkenes to a carbon atom next to carbon-carbon double bond.
c) Benzylic halide (aralalkyl halide): Halogens attached to alkenes to a carbon atom next to to an aromatic ring (not to a carbon atom in the aromatic ring). It is attached to a carbon atom which is inturn attached to a carbon atom in the aromatic ring.
2. Compounds containing sp2 hybridization
a) Vinylic halides: Halogens attached to alkenes to a carbon atom of one of the carbon atoms of a double bond.
B) Aryl halides: Halogens attached to alkenes to a carbon atom of an aromatic ring
Methods of preparation
1. From hydrocarbons
a) from alkanes: halogens react with alkanes in the presence of uv light to form haloalkanes.
b) from alkenes: by the electrophylic addition of halogen acids (HBr, HCl, or HI)
Markownikov rule and anti Markownikov rule are applicable in the reaction between alkene and halogen acids.
2. From alcohols: These reactions are covered in alcohol chapter also.
Reaction with phosphorus halides
Phosphorus halides such as PCl5, Pcl3, PBr3 and PI3 react with alcohols to form corresponding haloalkanes.
Haloalkanes : Chloroethane, Bromoethane, Iodoethane
Reaction with ZnCl2/conc.-HCl
This is a reaction or test to distinguish various categories of alcohols and is termed Lucas test.
In this test, an alcohol is treated with an equimolar mixture of concentrated hydrochloric acid and anhydrous ZnCl2 (called Lucas reagent).
Alcohols get converted into alkylhalides. As alkyl halides are insoluble in water, their presence is indicated by the appearance of turbidity in the reaction mixture.
Physical properties of halogenoalkanes
Boiling Points
the only methyl halide which is a liquid is iodomethane;
chloroethane is a gas.
The examples show that the boiling points fall as the isomers go from a primary to a secondary to a tertiary halogenoalkane. This is a simple result of the fall in the effectiveness of the dispersion forces.
Solubility in water
The halogenoalkanes are at best only very slightly soluble in water.
In order for a halogenoalkane to dissolve in water you have to break attractions between the halogenoalkane molecules (van der Waals dispersion and dipole-dipole interactions) and break the hydrogen bonds between water molecules. Both of these cost energy.
Solubility in organic solvents
Halogenoalkanes tend to dissolve in organic solvents because the new intermolecular attractions have much the same strength as the ones being broken in the separate halogenoalkane and solvent.
bond strength falls as you go from C-F to C-I, and notice how much stronger the carbon-fluorine bond is than the rest.
In order for anything to react with the halogenoalkanes, the carbon-halogen bond has got to be broken. Because that gets easier as you go from fluoride to chloride to bromide to iodide, the compounds get more reactive in that order.
Iodoalkanes are the most reactive and fluoroalkanes are the least. In fact, fluoroalkanes are so unreactive that we shall pretty well ignore them completely in discussion on reactions.
Nucleophilic substitution in primary halogenoalkanes
Nucleophiles
A nucleophile is a species (an ion or a molecule) which is strongly attracted to a region of positive charge in something else.
Nucleophiles are either fully negative ions, or else have a strongly - charge somewhere on a molecule. Common nucleophiles are hydroxide ions, cyanide ions, water and ammonia.
The nucleophilic substitution reaction - an SN2 reaction
Take bromoethane as a typical primary halogenoalkane. The bromoethane has a polar bond between the carbon and the bromine.The general purpose nucleophilic ion is referred to as Nu-. This will have at least one lone pair of electrons. Nu- could, for example, be OH- or CN-.
The lone pair on the Nu- ion will be strongly attracted to the + carbon, and will move towards it, beginning to make a co-ordinate (dative covalent) bond. In the process the electrons in the C-Br bond will be pushed even closer towards the bromine, making it increasingly negative.
The movement goes on until the -Nu is firmly attached to the carbon, and the bromine has been expelled as a Br- ion.
There is obviously a point in the reaction in which the Nu- is half attached to the carbon, and the C-Br bond is half way to being broken. This is called a transition state. It isn't an intermediate. You can't isolate it - even for a very short time. It's just the mid-point of a smooth attack by one group and the departure of another.
Technically, this is known as an SN2 reaction. S stands for substitution, N for nucleophilic, and the 2 is because the initial stage of the reaction involves two species - the bromoethane and the Nu- ion.
Nucleophilic substitution in tertiary halogenoalkanes
A tertiary halogenoalkane has three alkyl groups attached to the carbon with the halogen on it. These alkyl groups can be the same or different. The example uses a simple compound, (CH3)3CBr - 2-bromo-2-methylpropane.
The nucleophilic substitution reaction - an SN1 reaction (1 denotes 1st order)
The general purpose nucleophilic ion is termed as Nu-. This will have at least one lone pair of electrons.
The reaction happens in two stages. In the first, a small proportion of the halogenoalkane ionises to give a carbocation and a bromide ion.
Once the carbocation is formed, however, it would react immediately it came into contact with a nucleophile like Nu-. The lone pair on the nucleophile is strongly attracted towards the positive carbon, and moves towards it to create a new bond.
How fast the reaction happens is going to be governed by how fast the halogenoalkane ionises. Because this initial slow step only involves one species, the mechanism is described as SN1 - substitution, nucleophilic, one species taking part in the initial slow step.
Nucleophilic substitution reactions
1. substitution by hydroxylgroup (OH) leads to the formation of alcohols
2. substitution by alkoxy group leads to the formation of ether.
3.substitution by cyano group leads to the formation of cyanides or nitriles.
4. Substitution by isocyanide group leads to the formation of isocyanides.
When haloalkane is treated with alcoholic silver cyanide (AgCN), isocynaides (R-N≡C) are obtained. They are also called carbyl amines.
RX + AgCN ---> RNC + AGX
C2H5Br + AgCN ---> C2H5NC + Ag Br
5. substitution by amino group leads to the formation of amines.
6. substitution by nitrite group leads to the formation of nitrite.
7. substitution by nitro group leads to the formation of nitro alkanes.
8. substitution by carboxyl group leads to the formation of esters.
9. substitution by hydrosulphide group leads to the formation of thioalcohols.
10. substitution by mercaptide group leads to the formation of thioethers.
11. substitution by alkyl group leads to the formation of alkynes.
-----------
Note
Dibromoethane can refer to either of two isomeric organobromides with the molecuar formula C2H4Br2:
1,1-Dibromoethane (ethylidene dibromide)
1,2-Dibromoethane (ethylene dibromide)
For IIT JEE material on the same topic
http://iit-jee-chemistry.blogspot.com/2007/10/study-guide-tmh-jee-ch26-alkyl-and-aryl.html
Uses; Environmental effects of chloroform, iodoform, freons and DDT.
When hydrogen atom or atoms of alkanes are replaced by the corresponding number of halogen atoms, the compounds are called halogen derivatives of alkanes.
They are classified according to the number of halogen atoms that replace hydrogen atoms in the alkane.
Monohalogen derivatives: They contain only one halogen atom.
e.g. CH-3Cl Methyl chloride
CH-3-CH-CH-3 2-Bromopropane
!
Br
Monohalogen derivatives of alkane are called alkyl halides
Dihalogen alkanes contain two halogen atoms.
Trihalog alkanes contain three halogen atoms.
Monohalo alkanes
The general formula is RX where is a alkyl group and X is a halogen.
Classification of Haloalkanes
A. Type of halogen atoms; Fluorides, chlorides, bromides, iodides
B. Number of halogena atoms, monohalo, dihalo, trihalo, tetra halo.
Classification of Haloalkanes
1. Compounds containing sp3 hybridization
2. Compounds containing sp2 hybridization
Compounds containing sp3 hybridization
a) halo alkances or alkyl halides
(i)Primary halogenoalkanes
In a primary (1°) halogenoalkane, the carbon which carries the halogen atom is only attached to one other alkyl group.
Secondary halogenoalkanes
In a secondary (2°) halogenoalkane, the carbon with the halogen attached is joined directly to two other alkyl groups, which may be the same or different.
Tertiary halogenoalkanes
In a tertiary (3°) halogenoalkane, the carbon atom holding the halogen is attached directly to three alkyl groups, which may be any combination of same or different.
b) Allylic halides: Halogens attached to alkenes to a carbon atom next to carbon-carbon double bond.
c) Benzylic halide (aralalkyl halide): Halogens attached to alkenes to a carbon atom next to to an aromatic ring (not to a carbon atom in the aromatic ring). It is attached to a carbon atom which is inturn attached to a carbon atom in the aromatic ring.
2. Compounds containing sp2 hybridization
a) Vinylic halides: Halogens attached to alkenes to a carbon atom of one of the carbon atoms of a double bond.
B) Aryl halides: Halogens attached to alkenes to a carbon atom of an aromatic ring
Methods of preparation
1. From hydrocarbons
a) from alkanes: halogens react with alkanes in the presence of uv light to form haloalkanes.
b) from alkenes: by the electrophylic addition of halogen acids (HBr, HCl, or HI)
Markownikov rule and anti Markownikov rule are applicable in the reaction between alkene and halogen acids.
2. From alcohols: These reactions are covered in alcohol chapter also.
Reaction with phosphorus halides
Phosphorus halides such as PCl5, Pcl3, PBr3 and PI3 react with alcohols to form corresponding haloalkanes.
Haloalkanes : Chloroethane, Bromoethane, Iodoethane
Reaction with ZnCl2/conc.-HCl
This is a reaction or test to distinguish various categories of alcohols and is termed Lucas test.
In this test, an alcohol is treated with an equimolar mixture of concentrated hydrochloric acid and anhydrous ZnCl2 (called Lucas reagent).
Alcohols get converted into alkylhalides. As alkyl halides are insoluble in water, their presence is indicated by the appearance of turbidity in the reaction mixture.
Physical properties of halogenoalkanes
Boiling Points
the only methyl halide which is a liquid is iodomethane;
chloroethane is a gas.
The examples show that the boiling points fall as the isomers go from a primary to a secondary to a tertiary halogenoalkane. This is a simple result of the fall in the effectiveness of the dispersion forces.
Solubility in water
The halogenoalkanes are at best only very slightly soluble in water.
In order for a halogenoalkane to dissolve in water you have to break attractions between the halogenoalkane molecules (van der Waals dispersion and dipole-dipole interactions) and break the hydrogen bonds between water molecules. Both of these cost energy.
Solubility in organic solvents
Halogenoalkanes tend to dissolve in organic solvents because the new intermolecular attractions have much the same strength as the ones being broken in the separate halogenoalkane and solvent.
bond strength falls as you go from C-F to C-I, and notice how much stronger the carbon-fluorine bond is than the rest.
In order for anything to react with the halogenoalkanes, the carbon-halogen bond has got to be broken. Because that gets easier as you go from fluoride to chloride to bromide to iodide, the compounds get more reactive in that order.
Iodoalkanes are the most reactive and fluoroalkanes are the least. In fact, fluoroalkanes are so unreactive that we shall pretty well ignore them completely in discussion on reactions.
Nucleophilic substitution in primary halogenoalkanes
Nucleophiles
A nucleophile is a species (an ion or a molecule) which is strongly attracted to a region of positive charge in something else.
Nucleophiles are either fully negative ions, or else have a strongly - charge somewhere on a molecule. Common nucleophiles are hydroxide ions, cyanide ions, water and ammonia.
The nucleophilic substitution reaction - an SN2 reaction
Take bromoethane as a typical primary halogenoalkane. The bromoethane has a polar bond between the carbon and the bromine.The general purpose nucleophilic ion is referred to as Nu-. This will have at least one lone pair of electrons. Nu- could, for example, be OH- or CN-.
The lone pair on the Nu- ion will be strongly attracted to the + carbon, and will move towards it, beginning to make a co-ordinate (dative covalent) bond. In the process the electrons in the C-Br bond will be pushed even closer towards the bromine, making it increasingly negative.
The movement goes on until the -Nu is firmly attached to the carbon, and the bromine has been expelled as a Br- ion.
There is obviously a point in the reaction in which the Nu- is half attached to the carbon, and the C-Br bond is half way to being broken. This is called a transition state. It isn't an intermediate. You can't isolate it - even for a very short time. It's just the mid-point of a smooth attack by one group and the departure of another.
Technically, this is known as an SN2 reaction. S stands for substitution, N for nucleophilic, and the 2 is because the initial stage of the reaction involves two species - the bromoethane and the Nu- ion.
Nucleophilic substitution in tertiary halogenoalkanes
A tertiary halogenoalkane has three alkyl groups attached to the carbon with the halogen on it. These alkyl groups can be the same or different. The example uses a simple compound, (CH3)3CBr - 2-bromo-2-methylpropane.
The nucleophilic substitution reaction - an SN1 reaction (1 denotes 1st order)
The general purpose nucleophilic ion is termed as Nu-. This will have at least one lone pair of electrons.
The reaction happens in two stages. In the first, a small proportion of the halogenoalkane ionises to give a carbocation and a bromide ion.
Once the carbocation is formed, however, it would react immediately it came into contact with a nucleophile like Nu-. The lone pair on the nucleophile is strongly attracted towards the positive carbon, and moves towards it to create a new bond.
How fast the reaction happens is going to be governed by how fast the halogenoalkane ionises. Because this initial slow step only involves one species, the mechanism is described as SN1 - substitution, nucleophilic, one species taking part in the initial slow step.
Nucleophilic substitution reactions
1. substitution by hydroxylgroup (OH) leads to the formation of alcohols
2. substitution by alkoxy group leads to the formation of ether.
3.substitution by cyano group leads to the formation of cyanides or nitriles.
4. Substitution by isocyanide group leads to the formation of isocyanides.
When haloalkane is treated with alcoholic silver cyanide (AgCN), isocynaides (R-N≡C) are obtained. They are also called carbyl amines.
RX + AgCN ---> RNC + AGX
C2H5Br + AgCN ---> C2H5NC + Ag Br
5. substitution by amino group leads to the formation of amines.
6. substitution by nitrite group leads to the formation of nitrite.
7. substitution by nitro group leads to the formation of nitro alkanes.
8. substitution by carboxyl group leads to the formation of esters.
9. substitution by hydrosulphide group leads to the formation of thioalcohols.
10. substitution by mercaptide group leads to the formation of thioethers.
11. substitution by alkyl group leads to the formation of alkynes.
-----------
Note
Dibromoethane can refer to either of two isomeric organobromides with the molecuar formula C2H4Br2:
1,1-Dibromoethane (ethylidene dibromide)
1,2-Dibromoethane (ethylene dibromide)
For IIT JEE material on the same topic
http://iit-jee-chemistry.blogspot.com/2007/10/study-guide-tmh-jee-ch26-alkyl-and-aryl.html
Sunday, January 20, 2008
AIEEE Chemistry Unit 23A Organic Compounds Containing Oxygen
Syllabus
General methods of preparation, properties, reactions and uses.
ALCOHOLS, PHENOLS AND ETHERS:
Alcohols: Identification of primary, secondary and tertiary alcohols; mechanism of dehydration.
Phenols: Acidic nature, electrophilic substitution reactions: halogenation, nitration and sulphonation, Reimer - Tiemann reaction.
Ethers: Structure.
Aldehyde and Ketones: Nature of carbonyl group;
Nucleophilic addition to >C=O group, relative reactivities of aldehydes and ketones; Important reactions such as - Nucleophilic addition reactions (addition of HCN, NH3 and its derivatives), Grignard reagent; oxidation; reduction (Wolff Kishner and Clemmensen); acidity of ? - hydrogen, aldol condensation, Cannizzaro reaction, Haloform reaction; Chemical tests to distinguish between aldehydes and Ketones.
Carboxylic Acids: Acidic strength and factors affecting it.
-------------
Alcohols
Alcohols - Introduction
The hydroxy derivatives of aliphatic hydrocarbons are termed alcohols. They contain one or more hydroxyl (OH) groups.
Example:
Methyl Alcohol CH-3OH
Ehtyl alcohol C-2H-5OH also written as CH-3CH-2OH
Propyl alcohol C-3H-7OH also writtenas CH-3CH-2CH-2OH
They are classified according to the number of hydroxyl groups in the molecule.
One OH group in the molecule Monohydric alcohol
Two OH groups in the molecule Dihydric alcohol HOCH-2CH-2OH
Three OH groups in the molecule Trihydric alcohol
More than one OH group cannot be present on the same carbon atom. In such as a case, the compound will be extremely unstable and it will change into aldehyde. (This will be another topic in the syllabus itself)
Monohydric alcohols are further classified into Primary (1°), secondary(2°) and tertiary (3°) alcohols
Primary alcohols have one or none alkyl groups on the carbon bonded to -OH group.
secondary alcohols have two alkyl groups on the carbon bonded to -OH group.
Tertiary alcohols have three alkyl groups on the carbon bonded to -OH group.
IUPAC Nomenclature of Alcohols
Methanol
Ethanol
Propan-1-ol
Propan-2-ol
Butan-2-ol
2-Methylpropan-2-ol
Methods of Preparation of Alcohols
General Methods
1. preparation from haloalkanes
2. By reduction of aldehydes, ketones and esters
3. From Grignard reagents (RMgX)
4. By hydrolysis of eters
5. From alkenes
----a). hydration of alkenes
----b). Hydroboration oxidation reduction
----c). Oxymercuration - reduction
6. From aliphatic primary amines
Industrial Methods
1. Hydration of alkenes
2. Oxo Process
3. Fermentation of carbohydrates
4. manufacture of methanol
Physical Properties of alcohols
1. Physical state
2. solubility
3. Boiling points
4. Intoxicating effects
Chemical properties of alcohols
The reactions of alcohols are decribed under the following classification
A. Reactions involving cleavage of oxygen-hydrogen bond.
B. Reactions involving cleavage of carbon - oxygen bond
C. Reactions involving cleavage of both the alkyl and hydroxyl groups
A. Reactions involving cleavage of oxygen-hydrogen bond.
1. Reaction with active metals - acidic character
2. Reaction with metal hydrides
3. Reaction with carboxylic acids (esterification)
4. Reaction with grignard reagents.
5. Reaction with acyl chloride or acid anhydride
B. Reactions involving cleavage of carbon - oxygen bond
1. Reaction with hydrogen halides
2. Reaction with phosphorus halides
3. Reaction with thionyl chloride
C. Reactions involving cleavage of both the alkyl and hydroxyl groups
1. Acidic dehydration
2. Oxidation
3. dehydrogenation
Topics specifically highlighted in JEE syllabus
Esterification
Alcohols react with monocarboxylic acids, in the presence of concentrated sulphuric acid or dry HCL gas as catalyst, to from esters. This reaction is known as esterification.
The function of concentrated sulphuric acid is to act as protonating agent as well as a dehydrating agent.
RCOOH + HOR' ↔ RCOOR' + H2O with H2SO4 as catalyst
CH3COOH + HOC2H5 ↔ CH3COOC2H5 + H2O with H2SO4 as catalyst
The reaction is reversible is nature. Double headed arrow is used to indicate it. The equilibrium can be shifted toward the forward direction by removing water as soon as it is formed.
If dry HCL gas is used as a catalyst, the reaction is called Fisher=Speier esterification.
It is is difficult to prepare esters of tertiary alcohols becasue bulky groups in the alcohol decrease rate of reaction or esterification. This is termed as stearic hindrance of bulky groups.
As noted above in the reactions, esterification involved the cleavage of the O-H bonds of the alcohol. This was proved by using alcohol with isotopic O18 which can be tracked using isotopic tracer technique. It was found that this oxygen is present in the resulting ester which means that the oxygen in the alcohol is going into the ester and hydrogen is going into the water molecules.
Dehydration
When alcohols are heated with conc. or H3PO4, at 443 K, they get dehydrated to form alkenes.
The ease of dehydration of alcohol follows the order 3>2>1 which is also the order of stability of carbocation.
Dehydration of alcohols to ethers or alkenes can also be brought about by passing the vapour of the alcohols over heated alumina catalyst under different conditions
Oxidation
The oxidation of alcohols can be carried out by a number of reagents such as acqueous, alkalineor acidified KMnO4, acidified Na2Cr2O7, nitric acid, chromic acid, etc.
Different classes of alcohols differ from each other in their ease of oxidation and also give different products.
(i) Primary alcohols: Primary alcohols are easily oxidized. First an aldehyde is formed and then from it carboxylic acid is formed. Both the aldehyde and the resulting acid contain the same number of carbon atoms as the starting alcohol.
(ii) Secondary alcohols: Ease of oxidation is still there. But they are oxidized to ketone and under strong conditions they are further oxidized to form a mixture of acids. While the ketone contains the same number of carbon atoms as the starting alcohol, the acids formed contain lesser number of carbon atoms.
(iii) It is difficult to oxidize tertiarly alcohols.
When treated with acidic oxidizing agents under very strong conditions they form first ketones and then acids.
Both the ketones and acids contain lesser number of carbon atoms than the starting alcohols.
Reaction with sodium
The cleavage in this reaction will be in the OH bond. Alcohols react with active metals to liberate hydrogen gas an form metal alkoxide.
Ethanol or Ethyl alcohol reacts with sodium to gibve Sodium ethoxide and hydrogen
This reaction shows that alcohols are acidic in nature.
The acidic nature is due to the presence of polar O-H bond.
Alcohols are weak acids even weaker than water.
Reaction with phosphorus halides
Phosphorus halides such as PCl5, Pcl3, PBr3 and PI3 react with alcohols to form corresponding haloalkanes.
Haloalkanes : Chloroethane, Bromoethane, Iodoethane
Reaction with ZnCl2/conc.-HCl
This is a reaction or test to distinguish various categories of alcohols and is termed Lucas test.
In this test, an alcohol is treated with an equimolar mixture of concentrated hydrochloric acid and anhydrous ZnCl2 (called Lucas reagent).
Alcohols get converted into alkylhalides. As alkyl halides are insoluble in water, their presence is indicated by the appearance of turbidity in the reaction mixture.
The time required for the formation of alkyl halides and appearance of turbidity is very less in the tertiary alcohols.
in the case of secondary alcohols, it takes five minutes.
A primary alcohol produces turbidity only after heating.
Thus alcohols can be distinguished using Lucas test.
Conversion of alcohols into aldehydes and ketones
This topic was already covered in the topic of oxidation.
Oxidation of primary alcohol gives aldehydes.
Oxidation of secondary alcohols gives ketones.
It is difficult to oxidize tertiary alcohols.
Phenols: http://aieee-chemistry.blogspot.com/2008/01/aieee-chemistry-unit-23b-phenols.html
Ether
http://aieee-chemistry.blogspot.com/2008/01/aieee-chemistry-unit-23c-ethers.html
Aldehyes and Ketones
http://aieee-chemistry.blogspot.com/2008/01/aieee-chemistry-unit-23d-aldehydes-and.html
Carboxylic Acid
http://aieee-chemistry.blogspot.com/2008/01/aieee-chemistry-unit-23e-carboxylic.html
General methods of preparation, properties, reactions and uses.
ALCOHOLS, PHENOLS AND ETHERS:
Alcohols: Identification of primary, secondary and tertiary alcohols; mechanism of dehydration.
Phenols: Acidic nature, electrophilic substitution reactions: halogenation, nitration and sulphonation, Reimer - Tiemann reaction.
Ethers: Structure.
Aldehyde and Ketones: Nature of carbonyl group;
Nucleophilic addition to >C=O group, relative reactivities of aldehydes and ketones; Important reactions such as - Nucleophilic addition reactions (addition of HCN, NH3 and its derivatives), Grignard reagent; oxidation; reduction (Wolff Kishner and Clemmensen); acidity of ? - hydrogen, aldol condensation, Cannizzaro reaction, Haloform reaction; Chemical tests to distinguish between aldehydes and Ketones.
Carboxylic Acids: Acidic strength and factors affecting it.
-------------
Alcohols
Alcohols - Introduction
The hydroxy derivatives of aliphatic hydrocarbons are termed alcohols. They contain one or more hydroxyl (OH) groups.
Example:
Methyl Alcohol CH-3OH
Ehtyl alcohol C-2H-5OH also written as CH-3CH-2OH
Propyl alcohol C-3H-7OH also writtenas CH-3CH-2CH-2OH
They are classified according to the number of hydroxyl groups in the molecule.
One OH group in the molecule Monohydric alcohol
Two OH groups in the molecule Dihydric alcohol HOCH-2CH-2OH
Three OH groups in the molecule Trihydric alcohol
More than one OH group cannot be present on the same carbon atom. In such as a case, the compound will be extremely unstable and it will change into aldehyde. (This will be another topic in the syllabus itself)
Monohydric alcohols are further classified into Primary (1°), secondary(2°) and tertiary (3°) alcohols
Primary alcohols have one or none alkyl groups on the carbon bonded to -OH group.
secondary alcohols have two alkyl groups on the carbon bonded to -OH group.
Tertiary alcohols have three alkyl groups on the carbon bonded to -OH group.
IUPAC Nomenclature of Alcohols
Methanol
Ethanol
Propan-1-ol
Propan-2-ol
Butan-2-ol
2-Methylpropan-2-ol
Methods of Preparation of Alcohols
General Methods
1. preparation from haloalkanes
2. By reduction of aldehydes, ketones and esters
3. From Grignard reagents (RMgX)
4. By hydrolysis of eters
5. From alkenes
----a). hydration of alkenes
----b). Hydroboration oxidation reduction
----c). Oxymercuration - reduction
6. From aliphatic primary amines
Industrial Methods
1. Hydration of alkenes
2. Oxo Process
3. Fermentation of carbohydrates
4. manufacture of methanol
Physical Properties of alcohols
1. Physical state
2. solubility
3. Boiling points
4. Intoxicating effects
Chemical properties of alcohols
The reactions of alcohols are decribed under the following classification
A. Reactions involving cleavage of oxygen-hydrogen bond.
B. Reactions involving cleavage of carbon - oxygen bond
C. Reactions involving cleavage of both the alkyl and hydroxyl groups
A. Reactions involving cleavage of oxygen-hydrogen bond.
1. Reaction with active metals - acidic character
2. Reaction with metal hydrides
3. Reaction with carboxylic acids (esterification)
4. Reaction with grignard reagents.
5. Reaction with acyl chloride or acid anhydride
B. Reactions involving cleavage of carbon - oxygen bond
1. Reaction with hydrogen halides
2. Reaction with phosphorus halides
3. Reaction with thionyl chloride
C. Reactions involving cleavage of both the alkyl and hydroxyl groups
1. Acidic dehydration
2. Oxidation
3. dehydrogenation
Topics specifically highlighted in JEE syllabus
Esterification
Alcohols react with monocarboxylic acids, in the presence of concentrated sulphuric acid or dry HCL gas as catalyst, to from esters. This reaction is known as esterification.
The function of concentrated sulphuric acid is to act as protonating agent as well as a dehydrating agent.
RCOOH + HOR' ↔ RCOOR' + H2O with H2SO4 as catalyst
CH3COOH + HOC2H5 ↔ CH3COOC2H5 + H2O with H2SO4 as catalyst
The reaction is reversible is nature. Double headed arrow is used to indicate it. The equilibrium can be shifted toward the forward direction by removing water as soon as it is formed.
If dry HCL gas is used as a catalyst, the reaction is called Fisher=Speier esterification.
It is is difficult to prepare esters of tertiary alcohols becasue bulky groups in the alcohol decrease rate of reaction or esterification. This is termed as stearic hindrance of bulky groups.
As noted above in the reactions, esterification involved the cleavage of the O-H bonds of the alcohol. This was proved by using alcohol with isotopic O18 which can be tracked using isotopic tracer technique. It was found that this oxygen is present in the resulting ester which means that the oxygen in the alcohol is going into the ester and hydrogen is going into the water molecules.
Dehydration
When alcohols are heated with conc. or H3PO4, at 443 K, they get dehydrated to form alkenes.
The ease of dehydration of alcohol follows the order 3>2>1 which is also the order of stability of carbocation.
Dehydration of alcohols to ethers or alkenes can also be brought about by passing the vapour of the alcohols over heated alumina catalyst under different conditions
Oxidation
The oxidation of alcohols can be carried out by a number of reagents such as acqueous, alkalineor acidified KMnO4, acidified Na2Cr2O7, nitric acid, chromic acid, etc.
Different classes of alcohols differ from each other in their ease of oxidation and also give different products.
(i) Primary alcohols: Primary alcohols are easily oxidized. First an aldehyde is formed and then from it carboxylic acid is formed. Both the aldehyde and the resulting acid contain the same number of carbon atoms as the starting alcohol.
(ii) Secondary alcohols: Ease of oxidation is still there. But they are oxidized to ketone and under strong conditions they are further oxidized to form a mixture of acids. While the ketone contains the same number of carbon atoms as the starting alcohol, the acids formed contain lesser number of carbon atoms.
(iii) It is difficult to oxidize tertiarly alcohols.
When treated with acidic oxidizing agents under very strong conditions they form first ketones and then acids.
Both the ketones and acids contain lesser number of carbon atoms than the starting alcohols.
Reaction with sodium
The cleavage in this reaction will be in the OH bond. Alcohols react with active metals to liberate hydrogen gas an form metal alkoxide.
Ethanol or Ethyl alcohol reacts with sodium to gibve Sodium ethoxide and hydrogen
This reaction shows that alcohols are acidic in nature.
The acidic nature is due to the presence of polar O-H bond.
Alcohols are weak acids even weaker than water.
Reaction with phosphorus halides
Phosphorus halides such as PCl5, Pcl3, PBr3 and PI3 react with alcohols to form corresponding haloalkanes.
Haloalkanes : Chloroethane, Bromoethane, Iodoethane
Reaction with ZnCl2/conc.-HCl
This is a reaction or test to distinguish various categories of alcohols and is termed Lucas test.
In this test, an alcohol is treated with an equimolar mixture of concentrated hydrochloric acid and anhydrous ZnCl2 (called Lucas reagent).
Alcohols get converted into alkylhalides. As alkyl halides are insoluble in water, their presence is indicated by the appearance of turbidity in the reaction mixture.
The time required for the formation of alkyl halides and appearance of turbidity is very less in the tertiary alcohols.
in the case of secondary alcohols, it takes five minutes.
A primary alcohol produces turbidity only after heating.
Thus alcohols can be distinguished using Lucas test.
Conversion of alcohols into aldehydes and ketones
This topic was already covered in the topic of oxidation.
Oxidation of primary alcohol gives aldehydes.
Oxidation of secondary alcohols gives ketones.
It is difficult to oxidize tertiary alcohols.
Phenols: http://aieee-chemistry.blogspot.com/2008/01/aieee-chemistry-unit-23b-phenols.html
Ether
http://aieee-chemistry.blogspot.com/2008/01/aieee-chemistry-unit-23c-ethers.html
Aldehyes and Ketones
http://aieee-chemistry.blogspot.com/2008/01/aieee-chemistry-unit-23d-aldehydes-and.html
Carboxylic Acid
http://aieee-chemistry.blogspot.com/2008/01/aieee-chemistry-unit-23e-carboxylic.html
AIEEE Chemistry Unit 23B Phenols
Phenols: Introduction
Phenols are aromatic hydroxy compounds. In phenols, one or more hydroxyl group is directly attached to the aromatic (benzene) nucleus.
Phenols are also classified as monohydric, dihydric and trihydric or polyhydric as their molecules contain one, two, three or more OH groups.
Examples of Phenols
Monohydric
Phenol
2-Bromophenol
m-Cresol
p-Cresol
Dihydric
1,2-Dihydroxy benzene
Trihydric
1,2,3-Trihydroxy benzene
If OH group is not directly attached to be carbon atom in the benzene ring, but present in the molecule as a part of the alkyl side chain group, then the compound is not termed as phenol.
It is called aromatic alcohol because it resembles aliphatic alcohols in its characteristics.
Examples:
benzyl alcohol or Phenylmethanol
2-Phenylethanol
Nomenclature of Phenols
Common system
IUPAC system
All substituted phenols are named as derivatives of phenol.
The position of the substituents w.r.t.-OH group is indicated by Arabic numerals(with the carbon carrying-OH group being numbered 1).
Examples
2-Methyl phenol - Methyl group CH3 is present adjacent to OH group in phenol.
3-Methyl phenol - Methyl group CH3 is present in third position when OH group position is counted as 1 in phenol.
2-Bromophenol - Bromine is present adjacent to OH group in phenol.
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Phenols: Methods of Preparation
1. Alkali fusion of sodium benzene sulphonate
NaOH is fused with sodium benzene sulphonate at 573 - 623 K, sodium phenoxide is formed. This on acidification gives phenol.
2. From diazonium salts
An acqueous solution of benzene diazonium salt on warming gives phenol
3. By decarboxylation of sodium salt of salicyclic acid
Fusion of sodium salicylate with soda lime (NaOH and CaO mixture).
sodium phenoxide is formed. This on acidification gives phenol.
4. From Grignard reagent
when oxygen gas is bubbled through an ethereal solution of phenyl magnesium bromide (Grignard reagent RMgX), if forms an oxy compound which upon hydrolysis with dilute mineral acid gives phenol.
Commercial Preparation of Phenols
1. From chlorobenzene (Dow's Process)
Chlorobenzene is heated with 10% acqueous sodium hydroxide solution at about 623 K under 200 atmospheres andin the presence of copper salt acting as catalyst to form sodium phenoxide. The sodium salt when treated with dilute HCl, gives phenol.
2. From cumene
Air or oxygen is passed through a suspension of cumene in acqueous sodium carbonate solution in presence of cobalt or manganese naphthenate catalyst. The oxidation product is cumene hydroperoxide.
The hydroperoxide is then decomposed by hot dilute sulphuric acid when phenol is formed withliberation of acetone. Acetone is removed from phenol by distillation.
3. From Benzene (Raschig's method)
Vapours of HCl are passed over benzene at 500 K in the presence of copper chloride and excess of air to form chlorobenzene. Steam is then passed through chlorobenzene at 800 K in the presence of silica as catalyst to give phenol.
4. Phenol prepared using benzene and H2SO4
Benzene is heated with excess of concentrated sulphuric acid at about 388 K to give benzene sulphonic acid.
It is neutralized with sodium hydroxide solution, when sodium benzene sulphonate is obtained.
Dry sodium benzene sulphonate is next fused with excess of caustic soda at about 573 K when it yields sodium phenate (or sodium phenoxide).
Sodium phenate is decomposed by dilute sulphuric acid to give phenol.
Physical properties
1. State and smell: Phenols are colourless crystalline solids or liquids. They have characteristic phenolic odours.
2. solubility: Phenols are sparingly soluble in water
3. Boiling points: Higher than the boiling points of the aromatic hydrocarbons of comparable molecular masses.
BP of phenol (mol. mass = 94) is 455 K while that of toluene (mol mass = 92) is 384 K. This higher BP is due to intermolecular hydrogen bonding in phenols.
Chemical properties
Can be classified into three groups
A. Reactions of phenolic group (_OH group)
B. Reactions of benzene ring
C. Special reactions
A. Reactions of phenolic group (_OH group)
1. Action with zinc dust
2. Action with ammonia
3. Action with acid chlorides and acid anhydrides
4. Action with benzyl chloride
B. Reactions of benzene ring
1. Bromination
Action of Bromine water on phenol: When phenol is treated with bromine water, it gets decolourised giving a white precipitate of 2,4,6, tribromophenol.
Action of Bromine in CS-2 on phenol:o-Bromophenol + p-Bromophenol mixture is obtained. p-Bromophenol is the major product.
2. Nitration
Action of dilute nitirc acid on phenol: a mixture of o-nitrophenol and p-nitrophenol is formed.
Action of conc. nitric acid in the presence of conc. sulphuric acid on phenol: 2,4,6-trinitrophenol is formed. This is picric acid.
3. Nitrosation
The reaction which involves the substitution by nitroso grou (-NO) is called nitrosation.
Phenol reacts with nitrous acid (NaNO2 + HCl) at low temperature (280 K) to form p-nitrosophenol. It can be further oxidized with dil HNO3 to give p-nitrophenol.
4. Sulphonation: Covered as a special topic
5. Alkylation
Special reactions of Phenol
1. Kolbe's reaction: special topic
2. Reimer-Tiemann reaction: special topic
3. coupling reaction
4. Reaction with pthalic anhydride
5. Condensation with formaldehyde
6. Hydrogenation
7. Oxidation
8. Reaction with ferric chloride
9. Libermann's test
Acidity of Phenols
Phenols are weakly acidic in nature (Ka = 10^-10).
They turn blue litmus read and react with alkali metals and alkalies to form their salts.
The acidic character of phenol is due to polar OH bond.
Phenol is weaker acid than carboxylic acid.
Like carboxylic, it also does not react with sodium carbonate and sodium bicarbonate.
Phenols are more acidic than alcohols.
Phenol is a resonance hybrid of 5 structures. Three of the structures develop +charge on oxygen and facilitate release of H+.
Phenoxide ion which results when H+ is released from phenol is also a resonance hybrid but it is more stable than phenol. Hence the reaction is in favour of phenoxide ion. Therefore phenol is acidic and more acidic than alcohols.
Halogenation of Phenols (electrophylic substitution reaction)
The reaction does not require a lewis acid catalyst. Benzene requires a lewis acid catalyst for halogenation.
Bromine in CS2 reacts with phenol to give 4-Bromophenol(?)
Chlorine at high temperatures react with phenol to give 4-chlorophenol(?)
See http://clem.mscd.edu/~wiederm/oc2chp/oc2chpphenols/page3.htm
You can download a chapter on phenols from
http://www.diacritech.com/samples/science_and_medical/chemistry.pdf
Phenols are readily brominated in an aqueous solution forming 2, 4, 6-tribromophenol. This is a white precipitate.
Mostly p-bromophenol is obtained along with ortho bromophenol by treatment
of phenol with bromine in CCl4 or CS2.
Treatment of phenols with aqueous solutions of bromine results in replacement
of every hydrogen ortho or para to the -OH group. Bromination may
even cause displacement of certain other groups to yield tribromophenol.
Nitration of phenols
Action of dilute nitirc acid on phenol: a mixture of o-nitrophenol and p-nitrophenol is formed.
Action of conc. nitric acid in the presence of conc. sulphuric acid on phenol: 2,4,6-trinitrophenol is formed. This is picric acid.
Sulphonation
Action of conc. sulphuric acid at different temperatures on phenol:
Pheno reacts with conc. sulphuric acid to form a mixture of o-, and p-phenol sulphonic acid.
At low temperature about 288 to 293 K, o-phenol sulphonic acid is the main product formed.
At high temperature about 373 K, p-phenol sulphonic acid is the main product formed.
o-phenol sulphonic acid: IUPAC name is 2-Hydroxy benzene sulphonic acid
p-phenol sulphonic acid : IUPAC name is 4-Hydroxy benzene sulphonic acid
Phenols are aromatic hydroxy compounds. In phenols, one or more hydroxyl group is directly attached to the aromatic (benzene) nucleus.
Phenols are also classified as monohydric, dihydric and trihydric or polyhydric as their molecules contain one, two, three or more OH groups.
Examples of Phenols
Monohydric
Phenol
2-Bromophenol
m-Cresol
p-Cresol
Dihydric
1,2-Dihydroxy benzene
Trihydric
1,2,3-Trihydroxy benzene
If OH group is not directly attached to be carbon atom in the benzene ring, but present in the molecule as a part of the alkyl side chain group, then the compound is not termed as phenol.
It is called aromatic alcohol because it resembles aliphatic alcohols in its characteristics.
Examples:
benzyl alcohol or Phenylmethanol
2-Phenylethanol
Nomenclature of Phenols
Common system
IUPAC system
All substituted phenols are named as derivatives of phenol.
The position of the substituents w.r.t.-OH group is indicated by Arabic numerals(with the carbon carrying-OH group being numbered 1).
Examples
2-Methyl phenol - Methyl group CH3 is present adjacent to OH group in phenol.
3-Methyl phenol - Methyl group CH3 is present in third position when OH group position is counted as 1 in phenol.
2-Bromophenol - Bromine is present adjacent to OH group in phenol.
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Phenols: Methods of Preparation
1. Alkali fusion of sodium benzene sulphonate
NaOH is fused with sodium benzene sulphonate at 573 - 623 K, sodium phenoxide is formed. This on acidification gives phenol.
2. From diazonium salts
An acqueous solution of benzene diazonium salt on warming gives phenol
3. By decarboxylation of sodium salt of salicyclic acid
Fusion of sodium salicylate with soda lime (NaOH and CaO mixture).
sodium phenoxide is formed. This on acidification gives phenol.
4. From Grignard reagent
when oxygen gas is bubbled through an ethereal solution of phenyl magnesium bromide (Grignard reagent RMgX), if forms an oxy compound which upon hydrolysis with dilute mineral acid gives phenol.
Commercial Preparation of Phenols
1. From chlorobenzene (Dow's Process)
Chlorobenzene is heated with 10% acqueous sodium hydroxide solution at about 623 K under 200 atmospheres andin the presence of copper salt acting as catalyst to form sodium phenoxide. The sodium salt when treated with dilute HCl, gives phenol.
2. From cumene
Air or oxygen is passed through a suspension of cumene in acqueous sodium carbonate solution in presence of cobalt or manganese naphthenate catalyst. The oxidation product is cumene hydroperoxide.
The hydroperoxide is then decomposed by hot dilute sulphuric acid when phenol is formed withliberation of acetone. Acetone is removed from phenol by distillation.
3. From Benzene (Raschig's method)
Vapours of HCl are passed over benzene at 500 K in the presence of copper chloride and excess of air to form chlorobenzene. Steam is then passed through chlorobenzene at 800 K in the presence of silica as catalyst to give phenol.
4. Phenol prepared using benzene and H2SO4
Benzene is heated with excess of concentrated sulphuric acid at about 388 K to give benzene sulphonic acid.
It is neutralized with sodium hydroxide solution, when sodium benzene sulphonate is obtained.
Dry sodium benzene sulphonate is next fused with excess of caustic soda at about 573 K when it yields sodium phenate (or sodium phenoxide).
Sodium phenate is decomposed by dilute sulphuric acid to give phenol.
Physical properties
1. State and smell: Phenols are colourless crystalline solids or liquids. They have characteristic phenolic odours.
2. solubility: Phenols are sparingly soluble in water
3. Boiling points: Higher than the boiling points of the aromatic hydrocarbons of comparable molecular masses.
BP of phenol (mol. mass = 94) is 455 K while that of toluene (mol mass = 92) is 384 K. This higher BP is due to intermolecular hydrogen bonding in phenols.
Chemical properties
Can be classified into three groups
A. Reactions of phenolic group (_OH group)
B. Reactions of benzene ring
C. Special reactions
A. Reactions of phenolic group (_OH group)
1. Action with zinc dust
2. Action with ammonia
3. Action with acid chlorides and acid anhydrides
4. Action with benzyl chloride
B. Reactions of benzene ring
1. Bromination
Action of Bromine water on phenol: When phenol is treated with bromine water, it gets decolourised giving a white precipitate of 2,4,6, tribromophenol.
Action of Bromine in CS-2 on phenol:o-Bromophenol + p-Bromophenol mixture is obtained. p-Bromophenol is the major product.
2. Nitration
Action of dilute nitirc acid on phenol: a mixture of o-nitrophenol and p-nitrophenol is formed.
Action of conc. nitric acid in the presence of conc. sulphuric acid on phenol: 2,4,6-trinitrophenol is formed. This is picric acid.
3. Nitrosation
The reaction which involves the substitution by nitroso grou (-NO) is called nitrosation.
Phenol reacts with nitrous acid (NaNO2 + HCl) at low temperature (280 K) to form p-nitrosophenol. It can be further oxidized with dil HNO3 to give p-nitrophenol.
4. Sulphonation: Covered as a special topic
5. Alkylation
Special reactions of Phenol
1. Kolbe's reaction: special topic
2. Reimer-Tiemann reaction: special topic
3. coupling reaction
4. Reaction with pthalic anhydride
5. Condensation with formaldehyde
6. Hydrogenation
7. Oxidation
8. Reaction with ferric chloride
9. Libermann's test
Acidity of Phenols
Phenols are weakly acidic in nature (Ka = 10^-10).
They turn blue litmus read and react with alkali metals and alkalies to form their salts.
The acidic character of phenol is due to polar OH bond.
Phenol is weaker acid than carboxylic acid.
Like carboxylic, it also does not react with sodium carbonate and sodium bicarbonate.
Phenols are more acidic than alcohols.
Phenol is a resonance hybrid of 5 structures. Three of the structures develop +charge on oxygen and facilitate release of H+.
Phenoxide ion which results when H+ is released from phenol is also a resonance hybrid but it is more stable than phenol. Hence the reaction is in favour of phenoxide ion. Therefore phenol is acidic and more acidic than alcohols.
Halogenation of Phenols (electrophylic substitution reaction)
The reaction does not require a lewis acid catalyst. Benzene requires a lewis acid catalyst for halogenation.
Bromine in CS2 reacts with phenol to give 4-Bromophenol(?)
Chlorine at high temperatures react with phenol to give 4-chlorophenol(?)
See http://clem.mscd.edu/~wiederm/oc2chp/oc2chpphenols/page3.htm
You can download a chapter on phenols from
http://www.diacritech.com/samples/science_and_medical/chemistry.pdf
Phenols are readily brominated in an aqueous solution forming 2, 4, 6-tribromophenol. This is a white precipitate.
Mostly p-bromophenol is obtained along with ortho bromophenol by treatment
of phenol with bromine in CCl4 or CS2.
Treatment of phenols with aqueous solutions of bromine results in replacement
of every hydrogen ortho or para to the -OH group. Bromination may
even cause displacement of certain other groups to yield tribromophenol.
Nitration of phenols
Action of dilute nitirc acid on phenol: a mixture of o-nitrophenol and p-nitrophenol is formed.
Action of conc. nitric acid in the presence of conc. sulphuric acid on phenol: 2,4,6-trinitrophenol is formed. This is picric acid.
Sulphonation
Action of conc. sulphuric acid at different temperatures on phenol:
Pheno reacts with conc. sulphuric acid to form a mixture of o-, and p-phenol sulphonic acid.
At low temperature about 288 to 293 K, o-phenol sulphonic acid is the main product formed.
At high temperature about 373 K, p-phenol sulphonic acid is the main product formed.
o-phenol sulphonic acid: IUPAC name is 2-Hydroxy benzene sulphonic acid
p-phenol sulphonic acid : IUPAC name is 4-Hydroxy benzene sulphonic acid
AIEEE Chemistry Unit 23C Ethers
Ethers
(a) An ether is an oxygen bridge between two organic compounds.
For example: R-O-R'
(b) An alcohol is a special case of an ether, one in which one R is replaced with a hydrogen (for that matter, water could very well be considered to be an ether in which both R groups are replaced with hydrogens, though in this latter case one would no longer be referring to a organic compound).
(c) Conversely, the hydrogen of a hydroxyl group may be replaced with a organic compound. It occurs when two alcohols join through the loss of a water molecule in a reaction called dehydration synthesis: R-OH + HO-R' --> R-O-R' + HOH
(a) An ether is an oxygen bridge between two organic compounds.
For example: R-O-R'
(b) An alcohol is a special case of an ether, one in which one R is replaced with a hydrogen (for that matter, water could very well be considered to be an ether in which both R groups are replaced with hydrogens, though in this latter case one would no longer be referring to a organic compound).
(c) Conversely, the hydrogen of a hydroxyl group may be replaced with a organic compound. It occurs when two alcohols join through the loss of a water molecule in a reaction called dehydration synthesis: R-OH + HO-R' --> R-O-R' + HOH
AIEEE Chemistry Unit 23D Aldehydes and Ketones
Aldehydes contain carbonyl group C=O as functional group and the carbonyl atom carries at least one H atom.
Ketones
In ketones, also carbonyl group C=O is the functional group. But the carbonyl carbon does not contain any H atoms, but it is attached to two alkyl or aryl groups.
Nomenclature of Aldehydes and Ketones
Common names are used for the simplest aldehydes and ketones:
formaldehyde, butyraldehyde, benzaldehyde,
acetone, benzophenone, acetophenone
Common names are also used for carbonyl-containing substituent groups,
which are known collectively as acyl groups:
formyl, acetyl, benzoyl
Traditional names are used for a great many aldehydes and ketones which
were recognized as substances long before systems of nomenclature were
developed:
cinnamaldehyde, furfural, acrolein
Structure of Aldehydes and Ketones
• The carbonyl carbon of an aldehyde or ketone is sp2-hybridized.
-• The bond angle is close to 120° (trigonal planar).
• The carbon-oxygen double bond consists of:
– A sigma C-O bond
– A pi C=O bond
Properties of Aldehydes and Ketones
Aldehydes and ketones are polar molecules because the C=O bond has a
dipole moment:
• Their polarity makes aldehydes and ketones have higher boiling points than
alkenes of similar molecular weight.
• Aldehydes and ketones are not hydrogen bond donors (they can can’t donate a
proton); therefore, they have lower boiling points than alcohols of similar
molecular weight.
• Aldehydes and ketones are hydrogen bond acceptors; this makes them have
considerable solubilities in water.
Ketones such as acetone are good solvents because they dissolve both aqueous and organic compounds
Acetone is a polar, aprotic solvent.
Reactions of Aldehydes and Ketones
The reactions of aldehydes and ketones can be divided into two main
categories:
– Reactions of the carbonyl group
- Reactions involving the alpha-carbon
Carbonyl group reactions fall into three main groups:
– Reactions with acids
– Addition reactions
– Oxidation
Reactions with acids:
– The carbonyl oxygen is weakly basic.
– Both Bronsted and Lewis acids can interact with a lone pair of electrons on
the carbonyl oxygen.
Addition Reactions
– Carbonyl groups in aldehydes and ketones undergo addition reactions.
– This is one of the most important reactions of the carbonyl group.
Addition reactions occur by two different mechanisms:
– Base-catalyzed addition (under basic or neutral conditions)
– Acid-catalyzed addition (under acidic conditions)
• In some cases, we can carry out the same overall reaction using either set of
conditions (acidic or basic).
Oxidation
Carbonyl groups in aldehydes and ketones may be oxidized to form
compounds at the next “oxidation level”, that of carboxylic acids.
• Alcohols are oxidized to aldehydes and ketones
(example: biological oxidation of ethanol to acetaldehyde)
• The carbonyl group may be further oxidized to carboxylic acids
Basicity of Aldehydes and Ketones
Reactions which occur at the carbonyl oxygen xygen of aldehydes and ketones:
– The weakly basic carbonyl oxygen reacts with protons or Lewis acids
– The protonated form of the aldehyde or ketone is resonance-stabilized
– This gives the aldehyde/ketone conjugate acid carbocation character
Protonated aldehydes and ketones can be thought of as alpha-hydroxy carbocations
• When an alkyl group replaces (conceptually) the proton, an alpha-alkoxy
carbocation is formed:
Addition Using Grignard Reagents
• Primary, secondary and tertiary alcohols may be formed in the reactions of
aldehydes or ketones with Grignard reagents.
primary alcohols from formaldehyde
secondary alcohols from aldehydes
tertiary alcohols from ketones
Gatterman reaction?
The Gattermann reaction, named for the German chemist Ludwig Gattermann, in organic chemistry refers to a reaction of hydrocyanic acid with an aromatic compound, in this case benzene, under catalysis of with Friedel-Crafts catalyst (aluminium chloride).The reaction is similar to the Friedel-Crafts reaction.
See: http://en.wikipedia.org/wiki/Gattermann_reaction
Reducing R-COCl to an aldehyde?
By catalytic hydrogenation in the presence of palladium (Pd) catalyst supported over barium sulphate The catalytic mixture is poisoned by the addition of a small amount of sulphur or quinoline. This reaction is known as Rosemmund reduction.
Getting an aldehyde from methylbenzene
by oxidation
Getting ketone from alcohols?
By oxidation of secondary alcohols
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Ketones
In ketones, also carbonyl group C=O is the functional group. But the carbonyl carbon does not contain any H atoms, but it is attached to two alkyl or aryl groups.
Nomenclature of Aldehydes and Ketones
Common names are used for the simplest aldehydes and ketones:
formaldehyde, butyraldehyde, benzaldehyde,
acetone, benzophenone, acetophenone
Common names are also used for carbonyl-containing substituent groups,
which are known collectively as acyl groups:
formyl, acetyl, benzoyl
Traditional names are used for a great many aldehydes and ketones which
were recognized as substances long before systems of nomenclature were
developed:
cinnamaldehyde, furfural, acrolein
Structure of Aldehydes and Ketones
• The carbonyl carbon of an aldehyde or ketone is sp2-hybridized.
-• The bond angle is close to 120° (trigonal planar).
• The carbon-oxygen double bond consists of:
– A sigma C-O bond
– A pi C=O bond
Properties of Aldehydes and Ketones
Aldehydes and ketones are polar molecules because the C=O bond has a
dipole moment:
• Their polarity makes aldehydes and ketones have higher boiling points than
alkenes of similar molecular weight.
• Aldehydes and ketones are not hydrogen bond donors (they can can’t donate a
proton); therefore, they have lower boiling points than alcohols of similar
molecular weight.
• Aldehydes and ketones are hydrogen bond acceptors; this makes them have
considerable solubilities in water.
Ketones such as acetone are good solvents because they dissolve both aqueous and organic compounds
Acetone is a polar, aprotic solvent.
Reactions of Aldehydes and Ketones
The reactions of aldehydes and ketones can be divided into two main
categories:
– Reactions of the carbonyl group
- Reactions involving the alpha-carbon
Carbonyl group reactions fall into three main groups:
– Reactions with acids
– Addition reactions
– Oxidation
Reactions with acids:
– The carbonyl oxygen is weakly basic.
– Both Bronsted and Lewis acids can interact with a lone pair of electrons on
the carbonyl oxygen.
Addition Reactions
– Carbonyl groups in aldehydes and ketones undergo addition reactions.
– This is one of the most important reactions of the carbonyl group.
Addition reactions occur by two different mechanisms:
– Base-catalyzed addition (under basic or neutral conditions)
– Acid-catalyzed addition (under acidic conditions)
• In some cases, we can carry out the same overall reaction using either set of
conditions (acidic or basic).
Oxidation
Carbonyl groups in aldehydes and ketones may be oxidized to form
compounds at the next “oxidation level”, that of carboxylic acids.
• Alcohols are oxidized to aldehydes and ketones
(example: biological oxidation of ethanol to acetaldehyde)
• The carbonyl group may be further oxidized to carboxylic acids
Basicity of Aldehydes and Ketones
Reactions which occur at the carbonyl oxygen xygen of aldehydes and ketones:
– The weakly basic carbonyl oxygen reacts with protons or Lewis acids
– The protonated form of the aldehyde or ketone is resonance-stabilized
– This gives the aldehyde/ketone conjugate acid carbocation character
Protonated aldehydes and ketones can be thought of as alpha-hydroxy carbocations
• When an alkyl group replaces (conceptually) the proton, an alpha-alkoxy
carbocation is formed:
Addition Using Grignard Reagents
• Primary, secondary and tertiary alcohols may be formed in the reactions of
aldehydes or ketones with Grignard reagents.
primary alcohols from formaldehyde
secondary alcohols from aldehydes
tertiary alcohols from ketones
Gatterman reaction?
The Gattermann reaction, named for the German chemist Ludwig Gattermann, in organic chemistry refers to a reaction of hydrocyanic acid with an aromatic compound, in this case benzene, under catalysis of with Friedel-Crafts catalyst (aluminium chloride).The reaction is similar to the Friedel-Crafts reaction.
See: http://en.wikipedia.org/wiki/Gattermann_reaction
Reducing R-COCl to an aldehyde?
By catalytic hydrogenation in the presence of palladium (Pd) catalyst supported over barium sulphate The catalytic mixture is poisoned by the addition of a small amount of sulphur or quinoline. This reaction is known as Rosemmund reduction.
Getting an aldehyde from methylbenzene
by oxidation
Getting ketone from alcohols?
By oxidation of secondary alcohols
-----------------
AIEEE Chemistry Unit 23E Carboxylic Acids
Carboxylic acids are the compound containing carboxyl group in their molecules.
-c with a double bond with oxygen and single bond with OH
The carboxyl group is made up of carbonyl C with double bond with oxygen, and hydroxyl group OH. The carboxyl is formed carbo + oxyl.
These acides can be aliphatic or aromatic.
aliphatic acids
Formic acid HCOOH
Acetic acid CH-3COOH
Isobutyric acid (Branched)
aromatic acids
Bezoic acid : H in benzene substituted by COOH
m-Nitrobenzoic acid: One more H substituted by NO-2
o-Toluic acid (o refers to ortho) Benzoic acid with one more H substituted by CH-3
Dicarboxyic acids
Oxalic acid
Malonic acid
Succinic acid
Phthalic acid - It is an aromatic carboxylic acid
In the nomenclature, in common system, position of the sustituents is indicated by the greek letter alpha, beta, gamma and delta.
the carbon atom adjacent ot the carboxyl carbon is assigned the letter α, thenext carbon on chain is beta an so on.
According to the IUPAC system, the name of the acid is derived from the corresponding alkane by replacing the terminal 'e' with the '-oic' and adding the word acid.
The position of the substituents is indicated by the following rules:
1. The longest chain containing the carboxylic group (-COOH) is selected.
2. The carbon chain is numbered form the carboxylic acid group. The carbon of carboxyl group is always given number one.
3. The position of the substituents is indicated by the number.
Methods of Preparation of Monocarboxylic Acids:
1. From oxidation of primary alcohols
2. By oxidation of aldehydes and ketones.
3. By Hydrolysis of cyanides (or Nitriles)
4. By Grignard reaction
5. By hydrolysis of esters
6. By carboxylation of alkenes
7. From trihalogen derivatives of hydrocarbons
8. Aromatic acids from alkyl benzenes
Physical properties
State
B.P.
M.P.
Solubility
Reactions of carboxylic Acids
covered under the following heads
A. reactions due to hydrogen atom of carboxyl group
B. reactions due to OH carboxyl group
C. reactions due to carboxyl group
D. reactions due to alkyl group and benzene ring.
A. Reactions due to hydrogen atom of carboxyl group
1. Acidic Properties
B. Reactions due to OH carboxyl group
1. Formation of an acid anhydride
2. Formation of Esters
3. Formation of amides
4. Formation of acid chlorides
C. Reactions due to carboxyl group
1. Decarboxylation
2. Reduction
3. Action of bromine on silver salt of the acid
D. reactions due to alkyl group and benzene ring.
1. Halogenation
2. Ring substitution in aromatic acids
-c with a double bond with oxygen and single bond with OH
The carboxyl group is made up of carbonyl C with double bond with oxygen, and hydroxyl group OH. The carboxyl is formed carbo + oxyl.
These acides can be aliphatic or aromatic.
aliphatic acids
Formic acid HCOOH
Acetic acid CH-3COOH
Isobutyric acid (Branched)
aromatic acids
Bezoic acid : H in benzene substituted by COOH
m-Nitrobenzoic acid: One more H substituted by NO-2
o-Toluic acid (o refers to ortho) Benzoic acid with one more H substituted by CH-3
Dicarboxyic acids
Oxalic acid
Malonic acid
Succinic acid
Phthalic acid - It is an aromatic carboxylic acid
In the nomenclature, in common system, position of the sustituents is indicated by the greek letter alpha, beta, gamma and delta.
the carbon atom adjacent ot the carboxyl carbon is assigned the letter α, thenext carbon on chain is beta an so on.
According to the IUPAC system, the name of the acid is derived from the corresponding alkane by replacing the terminal 'e' with the '-oic' and adding the word acid.
The position of the substituents is indicated by the following rules:
1. The longest chain containing the carboxylic group (-COOH) is selected.
2. The carbon chain is numbered form the carboxylic acid group. The carbon of carboxyl group is always given number one.
3. The position of the substituents is indicated by the number.
Methods of Preparation of Monocarboxylic Acids:
1. From oxidation of primary alcohols
2. By oxidation of aldehydes and ketones.
3. By Hydrolysis of cyanides (or Nitriles)
4. By Grignard reaction
5. By hydrolysis of esters
6. By carboxylation of alkenes
7. From trihalogen derivatives of hydrocarbons
8. Aromatic acids from alkyl benzenes
Physical properties
State
B.P.
M.P.
Solubility
Reactions of carboxylic Acids
covered under the following heads
A. reactions due to hydrogen atom of carboxyl group
B. reactions due to OH carboxyl group
C. reactions due to carboxyl group
D. reactions due to alkyl group and benzene ring.
A. Reactions due to hydrogen atom of carboxyl group
1. Acidic Properties
B. Reactions due to OH carboxyl group
1. Formation of an acid anhydride
2. Formation of Esters
3. Formation of amides
4. Formation of acid chlorides
C. Reactions due to carboxyl group
1. Decarboxylation
2. Reduction
3. Action of bromine on silver salt of the acid
D. reactions due to alkyl group and benzene ring.
1. Halogenation
2. Ring substitution in aromatic acids
AIEEE Chemistry ORGANIC COMPOUNDS CONTAINING OXYGEN
General methods of preparation, properties, reactions and uses.
ALCOHOLS, PHENOLS AND ETHERS:
Alcohols: Identification of primary, secondary and tertiary alcohols; mechanism of dehydration.
Phenols: Acidic nature, electrophilic substitution reactions: halogenation, nitration and sulphonation, Reimer - Tiemann reaction.
Ethers: Structure.
Aldehyde and Ketones: Nature of carbonyl group;
Nucleophilic addition to >C=O group, relative reactivities of aldehydes and ketones; Important reactions such as - Nucleophilic addition reactions (addition of HCN, NH3 and its derivatives), Grignard reagent; oxidation; reduction (Wolff Kishner and Clemmensen); acidity of ? - hydrogen, aldol condensation, Cannizzaro reaction, Haloform reaction; Chemical tests to distinguish between aldehydes and Ketones.
Carboxylic Acids: Acidic strength and factors affecting it.
----------------
Alcohols - Introduction
The hydroxy derivatives of aliphatic hydrocarbons are termed alcohols. They contain one or more hydroxyl (OH) groups.
Example:
Methyl Alcohol CH-3OH
Ehtyl alcohol C-2H-5OH also written as CH-3CH-2OH
Propyl alcohol C-3H-7OH also writtenas CH-3CH-2CH-2OH
They are classified according to the number of hydroxyl groups in the molecule.
One OH group in the molecule Monohydric alcohol
Two OH groups in the molecule Dihydric alcohol HOCH-2CH-2OH
Three OH groups in the molecule Trihydric alcohol
More than one OH group cannot be present on the same carbon atom. In such as a case, the compound will be extremely unstable and it will change into aldehyde. (This will be another topic in the syllabus itself)
Monohydric alcohols are further classified into Primary (1°), secondary(2°) and tertiary (3°) alcohols
Primary alcohols have one or none alkyl groups on the carbon bonded to -OH group.
secondary alcohols have two alkyl groups on the carbon bonded to -OH group.
Tertiary alcohols have three alkyl groups on the carbon bonded to -OH group.
IUPAC Nomenclature of Alcohols
Methanol
Ethanol
Propan-1-ol
Propan-2-ol
Butan-2-ol
2-Methylpropan-2-ol
Methods of Preparation of Alcohols
General Methods
1. preparation from haloalkanes
2. By reduction of aldehydes, ketones and esters
3. From Grignard reagents (RMgX)
4. By hydrolysis of eters
5. From alkenes
----a). hydration of alkenes
----b). Hydroboration oxidation reduction
----c). Oxymercuration - reduction
6. From aliphatic primary amines
Industrial Methods
1. Hydration of alkenes
2. Oxo Process
3. Fermentation of carbohydrates
4. manufacture of methanol
Physical Properties of alcohols
1. Physical state
2. solubility
3. Boiling points
4. Intoxicating effects
Chemical properties of alcohols
The reactions of alcohols are decribed under the following classification
A. Reactions involving cleavage of oxygen-hydrogen bond.
B. Reactions involving cleavage of carbon - oxygen bond
C. Reactions involving cleavage of both the alkyl and hydroxyl groups
A. Reactions involving cleavage of oxygen-hydrogen bond.
1. Reaction with active metals - acidic character
2. Reaction with metal hydrides
3. Reaction with carboxylic acids (esterification)
4. Reaction with grignard reagents.
5. Reaction with acyl chloride or acid anhydride
B. Reactions involving cleavage of carbon - oxygen bond
1. Reaction with hydrogen halides
2. Reaction with phosphorus halides
3. Reaction with thionyl chloride
C. Reactions involving cleavage of both the alkyl and hydroxyl groups
1. Acidic dehydration
2. Oxidation
3. dehydrogenation
Esterification
Alcohols react with monocarboxylic acids, in the presence of concentrated sulphuric acid or dry HCL gas as catalyst, to from esters. This reaction is known as esterification.
The function of concentrated sulphuric acid is to act as protonating agent as well as a dehydrating agent.
RCOOH + HOR' ↔ RCOOR' + H2O with H2SO4 as catalyst
CH3COOH + HOC2H5 ↔ CH3COOC2H5 + H2O with H2SO4 as catalyst
The reaction is reversible is nature. Double headed arrow is used to indicate it. The equilibrium can be shifted toward the forward direction by removing water as soon as it is formed.
If dry HCL gas is used as a catalyst, the reaction is called Fisher=Speier esterification.
It is is difficult to prepare esters of tertiary alcohols becasue bulky groups in the alcohol decrease rate of reaction or esterification. This is termed as stearic hindrance of bulky groups.
As noted above in the reactions, esterification involved the cleavage of the O-H bonds of the alcohol. This was proved by using alcohol with isotopic O18 which can be tracked using isotopic tracer technique. It was found that this oxygen is present in the resulting ester which means that the oxygen in the alcohol is going into the ester and hydrogen is going into the water molecules.
Dehydration
When alcohols are heated with conc. or H3PO4, at 443 K, they get dehydrated to form alkenes.
The ease of dehydration of alcohol follows the order 3>2>1 which is also the order of stability of carbocation.
Dehydration of alcohols to ethers or alkenes can also be brought about by passing the vapour of the alcohols over heated alumina catalyst under different conditions
Oxidation
The oxidation of alcohols can be carried out by a number of reagents such as acqueous, alkalineor acidified KMnO4, acidified Na2Cr2O7, nitric acid, chromic acid, etc.
Different classes of alcohols differ from each other in their ease of oxidation and also give different products.
(i) Primary alcohols: Primary alcohols are easily oxidized. First an aldehyde is formed and then from it carboxylic acid is formed. Both the aldehyde and the resulting acid contain the same number of carbon atoms as the starting alcohol.
(ii) Secondary alcohols: Ease of oxidation is still there. But they are oxidized to ketone and under strong conditions they are further oxidized to form a mixture of acids. While the ketone contains the same number of carbon atoms as the starting alcohol, the acids formed contain lesser number of carbon atoms.
(iii) It is difficult to oxidize tertiarly alcohols.
When treated with acidic oxidizing agents under very strong conditions they form first ketones and then acids.
Both the ketones and acids contain lesser number of carbon atoms than the starting alcohols.
Reaction with sodium
The cleavage in this reaction will be in the OH bond. Alcohols react with active metals to liberate hydrogen gas an form metal alkoxide.
Ethanol or Ethyl alcohol reacts with sodium to gibve Sodium ethoxide and hydrogen
This reaction shows that alcohols are acidic in nature.
The acidic nature is due to the presence of polar O-H bond.
Alcohols are weak acids even weaker than water.
Reaction with phosphorus halides
Phosphorus halides such as PCl5, Pcl3, PBr3 and PI3 react with alcohols to form corresponding haloalkanes.
Haloalkanes : Chloroethane, Bromoethane, Iodoethane
Reaction with ZnCl2/conc.-HCl
This is a reaction or test to distinguish various categories of alcohols and is termed Lucas test.
In this test, an alcohol is treated with an equimolar mixture of concentrated hydrochloric acid and anhydrous ZnCl2 (called Lucas reagent).
Alcohols get converted into alkylhalides. As alkyl halides are insoluble in water, their presence is indicated by the appearance of turbidity in the reaction mixture.
The time required for the formation of alkyl halides and appearance of turbidity is very less in the tertiary alcohols.
in the case of secondary alcohols, it takes five minutes.
A primary alcohol produces turbidity only after heating.
Thus alcohols can be distinguished using Lucas test.
Conversion of alcohols into aldehydes and ketones
This topic was already covered in the topic of oxidation.
Oxidation of primary alcohol gives aldehydes.
Oxidation of secondary alcohols gives ketones.
It is difficult to oxidize tertiary alcohols.
ALCOHOLS, PHENOLS AND ETHERS:
Alcohols: Identification of primary, secondary and tertiary alcohols; mechanism of dehydration.
Phenols: Acidic nature, electrophilic substitution reactions: halogenation, nitration and sulphonation, Reimer - Tiemann reaction.
Ethers: Structure.
Aldehyde and Ketones: Nature of carbonyl group;
Nucleophilic addition to >C=O group, relative reactivities of aldehydes and ketones; Important reactions such as - Nucleophilic addition reactions (addition of HCN, NH3 and its derivatives), Grignard reagent; oxidation; reduction (Wolff Kishner and Clemmensen); acidity of ? - hydrogen, aldol condensation, Cannizzaro reaction, Haloform reaction; Chemical tests to distinguish between aldehydes and Ketones.
Carboxylic Acids: Acidic strength and factors affecting it.
----------------
Alcohols - Introduction
The hydroxy derivatives of aliphatic hydrocarbons are termed alcohols. They contain one or more hydroxyl (OH) groups.
Example:
Methyl Alcohol CH-3OH
Ehtyl alcohol C-2H-5OH also written as CH-3CH-2OH
Propyl alcohol C-3H-7OH also writtenas CH-3CH-2CH-2OH
They are classified according to the number of hydroxyl groups in the molecule.
One OH group in the molecule Monohydric alcohol
Two OH groups in the molecule Dihydric alcohol HOCH-2CH-2OH
Three OH groups in the molecule Trihydric alcohol
More than one OH group cannot be present on the same carbon atom. In such as a case, the compound will be extremely unstable and it will change into aldehyde. (This will be another topic in the syllabus itself)
Monohydric alcohols are further classified into Primary (1°), secondary(2°) and tertiary (3°) alcohols
Primary alcohols have one or none alkyl groups on the carbon bonded to -OH group.
secondary alcohols have two alkyl groups on the carbon bonded to -OH group.
Tertiary alcohols have three alkyl groups on the carbon bonded to -OH group.
IUPAC Nomenclature of Alcohols
Methanol
Ethanol
Propan-1-ol
Propan-2-ol
Butan-2-ol
2-Methylpropan-2-ol
Methods of Preparation of Alcohols
General Methods
1. preparation from haloalkanes
2. By reduction of aldehydes, ketones and esters
3. From Grignard reagents (RMgX)
4. By hydrolysis of eters
5. From alkenes
----a). hydration of alkenes
----b). Hydroboration oxidation reduction
----c). Oxymercuration - reduction
6. From aliphatic primary amines
Industrial Methods
1. Hydration of alkenes
2. Oxo Process
3. Fermentation of carbohydrates
4. manufacture of methanol
Physical Properties of alcohols
1. Physical state
2. solubility
3. Boiling points
4. Intoxicating effects
Chemical properties of alcohols
The reactions of alcohols are decribed under the following classification
A. Reactions involving cleavage of oxygen-hydrogen bond.
B. Reactions involving cleavage of carbon - oxygen bond
C. Reactions involving cleavage of both the alkyl and hydroxyl groups
A. Reactions involving cleavage of oxygen-hydrogen bond.
1. Reaction with active metals - acidic character
2. Reaction with metal hydrides
3. Reaction with carboxylic acids (esterification)
4. Reaction with grignard reagents.
5. Reaction with acyl chloride or acid anhydride
B. Reactions involving cleavage of carbon - oxygen bond
1. Reaction with hydrogen halides
2. Reaction with phosphorus halides
3. Reaction with thionyl chloride
C. Reactions involving cleavage of both the alkyl and hydroxyl groups
1. Acidic dehydration
2. Oxidation
3. dehydrogenation
Esterification
Alcohols react with monocarboxylic acids, in the presence of concentrated sulphuric acid or dry HCL gas as catalyst, to from esters. This reaction is known as esterification.
The function of concentrated sulphuric acid is to act as protonating agent as well as a dehydrating agent.
RCOOH + HOR' ↔ RCOOR' + H2O with H2SO4 as catalyst
CH3COOH + HOC2H5 ↔ CH3COOC2H5 + H2O with H2SO4 as catalyst
The reaction is reversible is nature. Double headed arrow is used to indicate it. The equilibrium can be shifted toward the forward direction by removing water as soon as it is formed.
If dry HCL gas is used as a catalyst, the reaction is called Fisher=Speier esterification.
It is is difficult to prepare esters of tertiary alcohols becasue bulky groups in the alcohol decrease rate of reaction or esterification. This is termed as stearic hindrance of bulky groups.
As noted above in the reactions, esterification involved the cleavage of the O-H bonds of the alcohol. This was proved by using alcohol with isotopic O18 which can be tracked using isotopic tracer technique. It was found that this oxygen is present in the resulting ester which means that the oxygen in the alcohol is going into the ester and hydrogen is going into the water molecules.
Dehydration
When alcohols are heated with conc. or H3PO4, at 443 K, they get dehydrated to form alkenes.
The ease of dehydration of alcohol follows the order 3>2>1 which is also the order of stability of carbocation.
Dehydration of alcohols to ethers or alkenes can also be brought about by passing the vapour of the alcohols over heated alumina catalyst under different conditions
Oxidation
The oxidation of alcohols can be carried out by a number of reagents such as acqueous, alkalineor acidified KMnO4, acidified Na2Cr2O7, nitric acid, chromic acid, etc.
Different classes of alcohols differ from each other in their ease of oxidation and also give different products.
(i) Primary alcohols: Primary alcohols are easily oxidized. First an aldehyde is formed and then from it carboxylic acid is formed. Both the aldehyde and the resulting acid contain the same number of carbon atoms as the starting alcohol.
(ii) Secondary alcohols: Ease of oxidation is still there. But they are oxidized to ketone and under strong conditions they are further oxidized to form a mixture of acids. While the ketone contains the same number of carbon atoms as the starting alcohol, the acids formed contain lesser number of carbon atoms.
(iii) It is difficult to oxidize tertiarly alcohols.
When treated with acidic oxidizing agents under very strong conditions they form first ketones and then acids.
Both the ketones and acids contain lesser number of carbon atoms than the starting alcohols.
Reaction with sodium
The cleavage in this reaction will be in the OH bond. Alcohols react with active metals to liberate hydrogen gas an form metal alkoxide.
Ethanol or Ethyl alcohol reacts with sodium to gibve Sodium ethoxide and hydrogen
This reaction shows that alcohols are acidic in nature.
The acidic nature is due to the presence of polar O-H bond.
Alcohols are weak acids even weaker than water.
Reaction with phosphorus halides
Phosphorus halides such as PCl5, Pcl3, PBr3 and PI3 react with alcohols to form corresponding haloalkanes.
Haloalkanes : Chloroethane, Bromoethane, Iodoethane
Reaction with ZnCl2/conc.-HCl
This is a reaction or test to distinguish various categories of alcohols and is termed Lucas test.
In this test, an alcohol is treated with an equimolar mixture of concentrated hydrochloric acid and anhydrous ZnCl2 (called Lucas reagent).
Alcohols get converted into alkylhalides. As alkyl halides are insoluble in water, their presence is indicated by the appearance of turbidity in the reaction mixture.
The time required for the formation of alkyl halides and appearance of turbidity is very less in the tertiary alcohols.
in the case of secondary alcohols, it takes five minutes.
A primary alcohol produces turbidity only after heating.
Thus alcohols can be distinguished using Lucas test.
Conversion of alcohols into aldehydes and ketones
This topic was already covered in the topic of oxidation.
Oxidation of primary alcohol gives aldehydes.
Oxidation of secondary alcohols gives ketones.
It is difficult to oxidize tertiary alcohols.
AIEEE Chemistry UNIT 24 Organic Compounds Containing Nitrogen
General methods of preparation, properties, reactions and uses.
Amines: Nomenclature, classification, structure, basic character and identification of primary, secondary and tertiary amines and their basic character.
Diazonium Salts: Importance in synthetic organic chemistry.
-----------------
Amines are regarded as derivatives of ammonia in which one, two or all three hydrogen atoms are replaced by alkyl or aryl group.
NH3 - H = RNH2; (Primary amine) characteritic group NH2 amino
RNH2 - H = R2NH;(secondary amine) characteritic group NH imino
R2NH - H = R3N (tertiary amine) characteritic group N tert-nitrogen
The amines are classified as primary, secondary and tertiary according to one, two or three hydrogen atoms of ammonia are replaced by alkyl or aryl groups.
In addition, there is another class known as quaternary ammonium compounds. These compounds are regarded as derivatives of ammonium salts in which all the four hydrogen atoms are replaced by alkyl or aryl groups.
Nomenclature of amines
IUPAC NAMES
Aliphatic amines
Methanamine
Ethanamine
1-Propanamine
2-Propanamines
N-methylmethanamine
N-Methylethanamine
N,N-Dimethylmethanamine
Aromatic amines
Benzenamine - can also be written as amino benzene
2-Methylbenzenamine
3-Methylbenzenamine
4-Methylbenzenamine
N-Methylbenzenamine
N,N-Dieethylbenzenamine
Preparation of amines
1. From alkyl halides
2. From Nitro compounds
3.From nitriles (cyanides) and isonitriles (isocyanides)
4. From amides
5. From oximes
6. from aldehydes and ketones
Industrial preparation
1. from alcohols
2.from aniline
Physical properties
1. State and smell
2. B.P.
Chemical Properties
1. Reaction with water (Basic character of amines)
2. Reaction with acids
3. Reaction with metal ions
4. Alkylation
5. Acylation (reaction with acid chlorides and acid anhydrides)
6. Benzoylation
7. schiff's base formation
8. Oxidation
9. Carbalamine reaction
10. Reaction with nitrous acid
11. Reaction with Grignard reagent
12. Carbon disulphide
13. Carbonyl chloride
14. Ring substitution in aromatic amines
15. coupling of diazonium salts
Amines: Nomenclature, classification, structure, basic character and identification of primary, secondary and tertiary amines and their basic character.
Diazonium Salts: Importance in synthetic organic chemistry.
-----------------
Amines are regarded as derivatives of ammonia in which one, two or all three hydrogen atoms are replaced by alkyl or aryl group.
NH3 - H = RNH2; (Primary amine) characteritic group NH2 amino
RNH2 - H = R2NH;(secondary amine) characteritic group NH imino
R2NH - H = R3N (tertiary amine) characteritic group N tert-nitrogen
The amines are classified as primary, secondary and tertiary according to one, two or three hydrogen atoms of ammonia are replaced by alkyl or aryl groups.
In addition, there is another class known as quaternary ammonium compounds. These compounds are regarded as derivatives of ammonium salts in which all the four hydrogen atoms are replaced by alkyl or aryl groups.
Nomenclature of amines
IUPAC NAMES
Aliphatic amines
Methanamine
Ethanamine
1-Propanamine
2-Propanamines
N-methylmethanamine
N-Methylethanamine
N,N-Dimethylmethanamine
Aromatic amines
Benzenamine - can also be written as amino benzene
2-Methylbenzenamine
3-Methylbenzenamine
4-Methylbenzenamine
N-Methylbenzenamine
N,N-Dieethylbenzenamine
Preparation of amines
1. From alkyl halides
2. From Nitro compounds
3.From nitriles (cyanides) and isonitriles (isocyanides)
4. From amides
5. From oximes
6. from aldehydes and ketones
Industrial preparation
1. from alcohols
2.from aniline
Physical properties
1. State and smell
2. B.P.
Chemical Properties
1. Reaction with water (Basic character of amines)
2. Reaction with acids
3. Reaction with metal ions
4. Alkylation
5. Acylation (reaction with acid chlorides and acid anhydrides)
6. Benzoylation
7. schiff's base formation
8. Oxidation
9. Carbalamine reaction
10. Reaction with nitrous acid
11. Reaction with Grignard reagent
12. Carbon disulphide
13. Carbonyl chloride
14. Ring substitution in aromatic amines
15. coupling of diazonium salts
AIEEE Chemistry UNIT 25 POLYMERS
Syllabus 2008
General introduction and classification of polymers, general methods of polymerization - addition and condensation, copolymerization; Natural and synthetic rubber and vulcanization; some important polymers with emphasis on their monomers and uses - polythene, nylon, polyester and bakelite.
--------------
A polymer is a large molecule built by repetitive binding together of many small units called monomers.
Homopolymer: A polymer derived from a single repeating monomer. Only one type of monomer will have repetitive binding and a large molecule appears.
Copolymer: When two or more monomer bind together in a repetitive manner and give rise to a large polymer, it is called copolymer.
Synthetic polymers are categorised as Chainr growth polymers and step growth polymers based on the method of preparation.
Chain growth polymers: Also called addition polymers.
Step Growth polymerss: Also called as condensation polymers
Classification based on physical properties
Elastomers
Fibre'
Thermoplastics
Thermosetting
Properties and uses Natural rubber
Rubber is a naturally occuring polymer. It is obtained as latex from rubber trees. It is highly elastic.
It is a polymer of isoprene (2-methyl buta-1,3-diene)
In natural rubber, about 11,000 to 20,000 isoprene units are linked together in a chain like arrangement.
Natural rubber is a thermoplastic. It becomes soft and sticky when heated. It is not hard and tough.t The properties can be modified and improved by the process of vulcanization.
Properties and uses cellulose
Properties and uses nylon
The monomer of nylon 6 is caprolactum.
fabrics, ropes and tyre cords are prepared using nylon 6.
For nylon 66, the monomers are hexamethylenediamine and adipic acid.
Bristles for brushes, and textile sheets are made using nylon 66
Properties and uses teflon
It is an addition polymer of tetrafluoroethylene.
nF2C=CF2 under heat and pressure (-F2C-CF2-)n
The double bond breaks and gets ready for bonding with a carbon on either side and the polymerisation takes place.
It is a tough material and is resistant towards heat, action of chemicals such as acids and bases. It is bad conductor of electricity.
Properties and uses PVC.
PVC is polyvinyl chloride
Its monomer is vinyl chloride. CH2=CHCl
PVC is prepared by heating vinyl chloride in an inert solvent in the presence of peroxides ( for instance, dibenboyl peroxide)
The double bond breaks and becomes ready bonding to carbon on either side and polymerisation takes place.
PVC is hard horny material. It is a thermoplastic polymer andits plasticity can be increased by the addition of plasticizer usch n-butylphthalate.
PVC is used in the manufacture of rain coats, hand bags, curtain clothes,and toys.
It is also used in articial flooring, as an insulating material in electric wires and for making gramophone records.
General introduction and classification of polymers, general methods of polymerization - addition and condensation, copolymerization; Natural and synthetic rubber and vulcanization; some important polymers with emphasis on their monomers and uses - polythene, nylon, polyester and bakelite.
--------------
A polymer is a large molecule built by repetitive binding together of many small units called monomers.
Homopolymer: A polymer derived from a single repeating monomer. Only one type of monomer will have repetitive binding and a large molecule appears.
Copolymer: When two or more monomer bind together in a repetitive manner and give rise to a large polymer, it is called copolymer.
Synthetic polymers are categorised as Chainr growth polymers and step growth polymers based on the method of preparation.
Chain growth polymers: Also called addition polymers.
Step Growth polymerss: Also called as condensation polymers
Classification based on physical properties
Elastomers
Fibre'
Thermoplastics
Thermosetting
Properties and uses Natural rubber
Rubber is a naturally occuring polymer. It is obtained as latex from rubber trees. It is highly elastic.
It is a polymer of isoprene (2-methyl buta-1,3-diene)
In natural rubber, about 11,000 to 20,000 isoprene units are linked together in a chain like arrangement.
Natural rubber is a thermoplastic. It becomes soft and sticky when heated. It is not hard and tough.t The properties can be modified and improved by the process of vulcanization.
Properties and uses cellulose
Properties and uses nylon
The monomer of nylon 6 is caprolactum.
fabrics, ropes and tyre cords are prepared using nylon 6.
For nylon 66, the monomers are hexamethylenediamine and adipic acid.
Bristles for brushes, and textile sheets are made using nylon 66
Properties and uses teflon
It is an addition polymer of tetrafluoroethylene.
nF2C=CF2 under heat and pressure (-F2C-CF2-)n
The double bond breaks and gets ready for bonding with a carbon on either side and the polymerisation takes place.
It is a tough material and is resistant towards heat, action of chemicals such as acids and bases. It is bad conductor of electricity.
Properties and uses PVC.
PVC is polyvinyl chloride
Its monomer is vinyl chloride. CH2=CHCl
PVC is prepared by heating vinyl chloride in an inert solvent in the presence of peroxides ( for instance, dibenboyl peroxide)
The double bond breaks and becomes ready bonding to carbon on either side and polymerisation takes place.
PVC is hard horny material. It is a thermoplastic polymer andits plasticity can be increased by the addition of plasticizer usch n-butylphthalate.
PVC is used in the manufacture of rain coats, hand bags, curtain clothes,and toys.
It is also used in articial flooring, as an insulating material in electric wires and for making gramophone records.
AIEEE Chemistry UNIT 26 BIO MOLECULES
Syllabus 2008
General introduction and importance of biomolecules.
CARBOHYDRATES - Classification: aldoses and ketoses; monosaccharides (glucose and fructose), constituent monosaccharides of oligosacchorides (sucrose, lactose, maltose) and polysaccharides (starch, cellulose, glycogen).
PROTEINS - Elementary Idea of ? - amino acids, peptide bond, polypeptides; Proteins: primary, secondary, tertiary and quaternary structure (qualitative idea only), denaturation of proteins, enzymes.
VITAMINS - Classification and functions.
NUCLEIC ACIDS - Chemical constitution of DNA and RNA.
Biological functions of nucleic acids.
--------
CARBOHYDRATES - Classification: aldoses and ketoses; monosaccharides (glucose and fructose), constituent monosaccharides of oligosacchorides (sucrose, lactose, maltose) and polysaccharides (starch, cellulose, glycogen).
Carbohydrates are classified as:
Monosaccharides
Oligosaccharides
Polysaccharides
Monohydrates may be represented as follows
H
!
C=O
!
(H-C-OH)-n
!
CH-2OH
A polyhdroxy aldehyde
CH-2OH
!
C=O
!
(H-C-OH)-n
!
CH-2OH
A polyhdroxy ketone
Monosaccharides are named as follows.
1. The calss name of monosaccharides begins with the prefix 'aldo' for polyhydroxy aldehydes and "keto' for polyhydroxy ketones.
2. the name ends with suffix 'ose".
3. In between prefix and suffix, the number of carbon atoms (i.e. di, tri, tetr etc.) is inserted.
Examples
H
|
C=O
|
(H-C-OH)
|
CH-2OH
Aldotriose - (A polyhdroxy aldehyde)
CH-2OH
|
C=O
|
CH-2OH
Ketotriose - (A polyhdroxy ketone )
Reducing and Nonreducing Sugars
Reducing sugars are easily oxidized to give carboxylic acid.
They reduce
(i) Tollens reagent (an ammoniacal solution of silver nitrate) to shiny silver mirror.
(ii) Fehling's solution (an acqueous solution of cupric iron and tartrate salts) to red precipitate of cuprous oxide, and
(iii) Benedict's reagent (an alkaline solution containing a cupric citrate complex) to red precipitate of curous oxide)
All aldoses are reducing sugars, but some ketoses are reducing sugars as well. For example, fructose (a ketose) reduces Tollens reagent. This occurs because fructose is readily isomerized to an aldose in basic solution.
amino acids are organic compounds containing both an amino group (NH2) and carboxylic group (COOH). They are represented by the general formula:
R
|
C-COOH
|
NH2
Essential amino acids
These amino acids are required by the body but are not made by our bodies. hence they must be supplied in diets.
Valine
Leucine
Isoleucine
Phenylalanine
Methionine
Trptophan
threonine
Lysine
Agrinine
L-Family of Amino Acids
With the exception of glycine, all other α amino acids have chiral carbon atom and have two optically active isomers.
However all naturally occurring amino acids belong to L series which have -NH2 group on the left.
Structure of Amino acids
amino acids exist as dipolar ion called a zwitter ion.
i) when an acid is added to an amino acid-COO- accepts this proton and therefore the basic character is due to -COO-group.
ii) When an alkali is added to amino acid -NH3+ group releases the proton and therefore acidic character is due to -NH3+ group.
Peptide
peptides are compounds formed by the condensation of two or more same or different α amino acids. The condensation occurs between amino acids with the elimination of water. In this case,the carboxyl group of one amino acid and amine group of another amino acid gets condensed with the elimination of water molecule. The resulting C-N linkage is called peptide linkage. The bond of C with O becomes a double bond.
The formation of peptide can be between two amino acid molecules or the number can go on until a single molecule containing several hundred thousands of aminoacids is formed.
Proteins
Structurally, proteins are long polymers of amino acids linked by peptide bonds
General introduction and importance of biomolecules.
CARBOHYDRATES - Classification: aldoses and ketoses; monosaccharides (glucose and fructose), constituent monosaccharides of oligosacchorides (sucrose, lactose, maltose) and polysaccharides (starch, cellulose, glycogen).
PROTEINS - Elementary Idea of ? - amino acids, peptide bond, polypeptides; Proteins: primary, secondary, tertiary and quaternary structure (qualitative idea only), denaturation of proteins, enzymes.
VITAMINS - Classification and functions.
NUCLEIC ACIDS - Chemical constitution of DNA and RNA.
Biological functions of nucleic acids.
--------
CARBOHYDRATES - Classification: aldoses and ketoses; monosaccharides (glucose and fructose), constituent monosaccharides of oligosacchorides (sucrose, lactose, maltose) and polysaccharides (starch, cellulose, glycogen).
Carbohydrates are classified as:
Monosaccharides
Oligosaccharides
Polysaccharides
Monohydrates may be represented as follows
H
!
C=O
!
(H-C-OH)-n
!
CH-2OH
A polyhdroxy aldehyde
CH-2OH
!
C=O
!
(H-C-OH)-n
!
CH-2OH
A polyhdroxy ketone
Monosaccharides are named as follows.
1. The calss name of monosaccharides begins with the prefix 'aldo' for polyhydroxy aldehydes and "keto' for polyhydroxy ketones.
2. the name ends with suffix 'ose".
3. In between prefix and suffix, the number of carbon atoms (i.e. di, tri, tetr etc.) is inserted.
Examples
H
|
C=O
|
(H-C-OH)
|
CH-2OH
Aldotriose - (A polyhdroxy aldehyde)
CH-2OH
|
C=O
|
CH-2OH
Ketotriose - (A polyhdroxy ketone )
Reducing and Nonreducing Sugars
Reducing sugars are easily oxidized to give carboxylic acid.
They reduce
(i) Tollens reagent (an ammoniacal solution of silver nitrate) to shiny silver mirror.
(ii) Fehling's solution (an acqueous solution of cupric iron and tartrate salts) to red precipitate of cuprous oxide, and
(iii) Benedict's reagent (an alkaline solution containing a cupric citrate complex) to red precipitate of curous oxide)
All aldoses are reducing sugars, but some ketoses are reducing sugars as well. For example, fructose (a ketose) reduces Tollens reagent. This occurs because fructose is readily isomerized to an aldose in basic solution.
amino acids are organic compounds containing both an amino group (NH2) and carboxylic group (COOH). They are represented by the general formula:
R
|
C-COOH
|
NH2
Essential amino acids
These amino acids are required by the body but are not made by our bodies. hence they must be supplied in diets.
Valine
Leucine
Isoleucine
Phenylalanine
Methionine
Trptophan
threonine
Lysine
Agrinine
L-Family of Amino Acids
With the exception of glycine, all other α amino acids have chiral carbon atom and have two optically active isomers.
However all naturally occurring amino acids belong to L series which have -NH2 group on the left.
Structure of Amino acids
amino acids exist as dipolar ion called a zwitter ion.
i) when an acid is added to an amino acid-COO- accepts this proton and therefore the basic character is due to -COO-group.
ii) When an alkali is added to amino acid -NH3+ group releases the proton and therefore acidic character is due to -NH3+ group.
Peptide
peptides are compounds formed by the condensation of two or more same or different α amino acids. The condensation occurs between amino acids with the elimination of water. In this case,the carboxyl group of one amino acid and amine group of another amino acid gets condensed with the elimination of water molecule. The resulting C-N linkage is called peptide linkage. The bond of C with O becomes a double bond.
The formation of peptide can be between two amino acid molecules or the number can go on until a single molecule containing several hundred thousands of aminoacids is formed.
Proteins
Structurally, proteins are long polymers of amino acids linked by peptide bonds
AIEEE Chemistry - UNIT 27 CHEMISTRY IN EVERYDAY LIFE
2008 syllabus
Chemicals in medicines: Analgesics, tranquilizers, antiseptics, disinfectants, antimicrobials, antifertility drugs, antibiotics, antacids, antihistamins - their meaning and common examples.
Chemicals in food: Preservatives, artificial sweetening agents - common examples.
Cleansing agents: Soaps and detergents, cleansing action.
---------------
1. Antipyretics
Aspirin, paracewtamol and phenacetin
2. Analgesics
Aspirin, anlgin, novalgin
3. Antiseptics and disinfectants
Cl2, Dettol, Bithiional, hexachlorprene, Amyl metacresol, Iodine,
4. Antimalarials
chlorquine, paraquine, primaquine
5. Tranquilizers
Equanil
6. Antimicrobials
sulphonamide
2. Chemicals in Food
1. Preservatives
Sodium benzoate
potassium metabisulphite
2. Artificial sweetening agents
3. Antioxidants
Chemicals in medicines: Analgesics, tranquilizers, antiseptics, disinfectants, antimicrobials, antifertility drugs, antibiotics, antacids, antihistamins - their meaning and common examples.
Chemicals in food: Preservatives, artificial sweetening agents - common examples.
Cleansing agents: Soaps and detergents, cleansing action.
---------------
1. Antipyretics
Aspirin, paracewtamol and phenacetin
2. Analgesics
Aspirin, anlgin, novalgin
3. Antiseptics and disinfectants
Cl2, Dettol, Bithiional, hexachlorprene, Amyl metacresol, Iodine,
4. Antimalarials
chlorquine, paraquine, primaquine
5. Tranquilizers
Equanil
6. Antimicrobials
sulphonamide
2. Chemicals in Food
1. Preservatives
Sodium benzoate
potassium metabisulphite
2. Artificial sweetening agents
3. Antioxidants
Saturday, January 19, 2008
AIEEE Chemistry UNIT 28 PRINCIPLES RELATED TO PRACTICAL CHEMISTRY Study Guide
AIEEE 2008 Syllabus
UNIT 28 PRINCIPLES RELATED TO PRACTICAL CHEMISTRY
► Detection of extra elements (N,S, halogens) in organic compounds; Detection of the following functional groups: hydroxyl (alcoholic and phenolic), carbonyl (aldehyde and ketone), carboxyl and amino groups in organic compounds.
► Chemistry involved in the preparation of the following:
Inorganic compounds: Mohr’s salt, potash alum.
Organic compounds: Acetanilide, p-nitroacetanilide, aniline yellow, iodoform.
► Chemistry involved in the titrimetric excercises - Acids bases and the use of indicators, oxalic-acid vs KMnO4, Mohr’s salt vs KMnO4.
► Chemical principles involved in the qualitative salt analysis:
Cations - Pb2+ , Cu2+, AI3+, Fe3+, Zn2+, Ni2+, Ca2+, Ba2+, Mg2+, NH4+.
Anions- CO32-, S2-, SO42-, NO2-, NO3-, CI-, Br, I. (Insoluble salts excluded).
► Chemical principles involved in the following experiments:
1 Enthalpy of solution of CuSO4
2 Enthalpy of neutralization of strong acid and strong base.
3 Preparation of lyophilic and lyophobic sols.
4 Kinetic study of reaction of iodide ion with hydrogen peroxide at room temperature.
Study Guide
----------
1.Lassaigne test is used for detecting N,S, halogens.
2.Sodium extract of the given compound is prepared first to do Lassaigne test.
3.Ferrous sulphate is used for nitrogen detection, acetic acid and lead acetate for detecting sulphur and NH4OH is used for detecting halogens.
4. Sodium test is used for detecting OH group
5. Ferric chloride test is used detecting phenolic group.
6. 2,4 dinitrophenylhydrazine test used to find the presence of carbonyl group.
7. Tollens reagent test is used for detecting aldehydic group.
8. If a carbonyl group is present, but aldehydic group is not detected, it means ketonic group is there.
9. Bicarbonate test will indicte carboxylic group -COOH
10. Isocyanide test will indicate presence of amine -NH2 group.
UNIT 28 PRINCIPLES RELATED TO PRACTICAL CHEMISTRY
► Detection of extra elements (N,S, halogens) in organic compounds; Detection of the following functional groups: hydroxyl (alcoholic and phenolic), carbonyl (aldehyde and ketone), carboxyl and amino groups in organic compounds.
► Chemistry involved in the preparation of the following:
Inorganic compounds: Mohr’s salt, potash alum.
Organic compounds: Acetanilide, p-nitroacetanilide, aniline yellow, iodoform.
► Chemistry involved in the titrimetric excercises - Acids bases and the use of indicators, oxalic-acid vs KMnO4, Mohr’s salt vs KMnO4.
► Chemical principles involved in the qualitative salt analysis:
Cations - Pb2+ , Cu2+, AI3+, Fe3+, Zn2+, Ni2+, Ca2+, Ba2+, Mg2+, NH4+.
Anions- CO32-, S2-, SO42-, NO2-, NO3-, CI-, Br, I. (Insoluble salts excluded).
► Chemical principles involved in the following experiments:
1 Enthalpy of solution of CuSO4
2 Enthalpy of neutralization of strong acid and strong base.
3 Preparation of lyophilic and lyophobic sols.
4 Kinetic study of reaction of iodide ion with hydrogen peroxide at room temperature.
Study Guide
----------
1.Lassaigne test is used for detecting N,S, halogens.
2.Sodium extract of the given compound is prepared first to do Lassaigne test.
3.Ferrous sulphate is used for nitrogen detection, acetic acid and lead acetate for detecting sulphur and NH4OH is used for detecting halogens.
4. Sodium test is used for detecting OH group
5. Ferric chloride test is used detecting phenolic group.
6. 2,4 dinitrophenylhydrazine test used to find the presence of carbonyl group.
7. Tollens reagent test is used for detecting aldehydic group.
8. If a carbonyl group is present, but aldehydic group is not detected, it means ketonic group is there.
9. Bicarbonate test will indicte carboxylic group -COOH
10. Isocyanide test will indicate presence of amine -NH2 group.
AIEEE 2008 Syllabus - Chemistry
CHEMISTRY
UNIT 1 SOME BASIC CONCEPTS IN CHEMISTRY
Matter and its nature, Dalton’s atomic theory; Concept of atom, molecule, element and compound; Physical quantities and their measurements in Chemistry, precision and accuracy, significant figures, S.I. Units, dimensional analysis; Laws of chemical combination; Atomic and molecular masses, mole concept, molar mass, percentage composition, empirical and molecular formulae; Chemical equations and stoichiometry.
UNIT 2 STATES OF MATTER
Classification of matter into solid, liquid and gaseous states.
Gaseous State:
Measurable properties of gases; Gas laws - Boyle’s law, Charle’s law, Graham’s law of diffusion, Avogadro’s law, Dalton’s law of partial pressure; Concept of Absolute scale of temperature; Ideal gas equation, Kinetic theory of gases (only postulates); Concept of average, root mean square and most probable velocities; Real gases, deviation from Ideal behaviour, compressibility factor, van der Waals equation, liquefaction of gases, critical constants.
Liquid State:
Properties of liquids - vapour pressure, viscosity and surface tension and effect of temperature on them (qualitative treatment only).
Solid State:
Classification of solids: molecular, ionic, covalent and metallic solids, amorphous and crystalline solids (elementary idea); Bragg’s Law and its applications; Unit cell and lattices, packing in solids (fcc, bcc and hcp lattices), voids, calculations involving unit cell parameters, imperfection in solids; Electrical, magnetic and dielectric properties.
UNIT 3 ATOMIC STRUCTURE
Discovery of sub-atomic particles (electron, proton and neutron); Thomson and Rutherford atomic models and their limitations; Nature of electromagnetic radiation, photoelectric effect; Spectrum of hydrogen atom, Bohr model of hydrogen atom - its postulates, derivation of the relations for energy of the electron and radii of the different orbits, limitations of Bohr’s model; Dual nature of matter, de-Broglie’s relationship, Heisenberg uncertainty principle. Elementary ideas of quantum mechanics, quantum mechanical model of atom, its important features, * and *2, concept of atomic orbitals as one electron wave functions; Variation of * and * 2 with r for 1s and 2s orbitals; various quantum numbers (principal, angular momentum and magnetic quantum numbers) and their significance; shapes of s, p and d - orbitals, electron spin and spin quantum number; Rules for filling electrons in orbitals – aufbau principle, Pauli’s exclusion principle and Hund’s rule, electronic configuration of elements, extra stability of half-filled and completely filled orbitals.
UNIT 4 CHEMICAL BONDING AND MOLECULAR STRUCTURE
Kossel: Lewis approach to chemical bond formation, concept of ionic and covalent bonds.
Ionic Bonding: Formation of ionic bonds, factors affecting the formation of ionic bonds; calculation of lattice enthalpy.
Covalent Bonding: Concept of electronegativity, Fajan’s rule, dipole moment; Valence Shell Electron Pair Repulsion (VSEPR) theory and shapes of simple molecules.
Quantum mechanical approach to covalent bonding: Valence bond theory - Its important features, concept of hybridization involving s, p and d orbitals; Resonance.
Molecular Orbital Theory: Its important features, LCAOs, types of molecular orbitals (bonding, antibonding), sigma and pi-bonds, molecular orbital electronic configurations of homonuclear diatomic molecules, concept of bond order, bond length and bond energy.
Elementary idea of metallic bonding. Hydrogen bonding and its applications.
UNIT 5 CHEMICAL THERMODYNAMICS
Fundamentals of thermodynamics: System and surroundings, extensive and intensive properties, state functions, types of processes.
First law of thermodynamics - Concept of work, heat internal energy and enthalpy, heat capacity, molar heat capacity; Hess’s law of constant heat summation; Enthalpies of bond dissociation, combustion, formation, atomization, sublimation, phase transition, hydration, ionization and solution.
Second law of thermodynamics- Spontaneity of processes; DS of the universe and DG of the system as criteria for spontaneity, DGo (Standard Gibbs energy change) and equilibrium constant.
UNIT 6 SOLUTIONS
Different methods for expressing concentration of solution - molality, molarity, mole fraction, percentage (by volume and mass both), vapour pressure of solutions and Raoult’s Law - Ideal and non-ideal solutions, vapour pressure - composition, plots for ideal and non-ideal solutions; Colligative properties of dilute solutions - relative lowering of vapour pressure, depression of freezing point, elevation of boiling point and osmotic pressure; Determination of molecular mass using colligative properties; Abnormal value of molar mass, van’t Hoff factor and its significance.
UNIT 7 EQUILIBRIUM
Meaning of equilibrium, concept of dynamic equilibrium.
Equilibria involving physical processes: Solid -liquid, liquid - gas and solid - gas equilibria, Henry’s law, general characterics of equilibrium involving physical processes.
Equilibria involving chemical processes: Law of chemical equilibrium, equilibrium constants (Kp and Kc) and their significance, significance of DG and DGo in chemical equilibria, factors affecting equilibrium concentration, pressure, temperature, effect of catalyst; Le Chatelier’s principle.
Ionic equilibrium: Weak and strong electrolytes, ionization of electrolytes, various concepts of acids and bases (Arrhenius, Br?nsted - Lowry and Lewis) and their ionization, acid - base equilibria (including multistage ionization) and ionization constants, ionization of water, pH scale, common ion effect, hydrolysis of salts and pH of their solutions, solubility of sparingly soluble salts and solubility products, buffer solutions.
UNIT 8 REDOX REACTIONS AND ELECTROCHEMISTRY
Electronic concepts of oxidation and reduction, redox reactions, oxidation number, rules for assigning oxidation number, balancing of redox reactions.
Eectrolytic and metallic conduction, conductance in electrolytic solutions, specific and molar conductivities and their variation with concentration: Kohlrausch’s law and its applications.
Electrochemical cells - Electrolytic and Galvanic cells, different types of electrodes, electrode potentials including standard electrode potential, half - cell and cell reactions, emf of a Galvanic cell and its measurement; Nernst equation and its applications; Relationship between cell potential and Gibbs’ energy change; Dry cell and lead accumulator; Fuel cells; Corrosion and its prevention.
UNIT 9 CHEMICAL KINETICS
Rate of a chemical reaction, factors affecting the rate of reactions: concentration, temperature, pressure and catalyst; elementary and complex reactions, order and molecularity of reactions, rate law, rate constant and its units, differential and integral forms of zero and first order reactions, their characteristics and half - lives, effect of temperature on rate of reactions - Arrhenius theory, activation energy and its calculation, collision theory of bimolecular gaseous reactions (no derivation).
UNIT 10 SURFACE CHEMISTRY
Adsorption- Physisorption and chemisorption and their characteristics, factors affecting adsorption of gases on solids - Freundlich and Langmuir adsorption isotherms, adsorption from solutions.
Catalysis- Homogeneous and heterogeneous, activity and selectivity of solid catalysts, enzyme catalysis and its mechanism.
Colloidal state- distinction among true solutions, colloids and suspensions, classification of colloids - lyophilic, lyophobic; multi molecular, macromolecular and associated colloids (micelles), preparation and properties of colloids - Tyndall effect, Brownian movement, electrophoresis, dialysis, coagulation and flocculation; Emulsions and their characteristics
SECTION-B
INORGANIC CHEMISTRY
UNIT 11 CLASSIFICATON OF ELEMENTS AND PERIODICITY IN PROPERTIES
Modem periodic law and present form of the periodic table, s, p, d and f block elements, periodic trends in properties of elementsatomic and ionic radii, ionization enthalpy, electron gain enthalpy, valence, oxidation states and chemical reactivity.
UNIT 12 GENERAL PRINCIPLES AND PROCESSES OF ISOLATION OF METALS
Modes of occurrence of elements in nature, minerals, ores; steps involved in the extraction of metals - concentration, reduction (chemical. and electrolytic methods) and refining with special reference to the extraction of Al, Cu, Zn and Fe; Thermodynamic and electrochemical principles involved in the extraction of metals.
UNIT 13 HYDROGEN
Position of hydrogen in periodic table, isotopes, preparation, properties and uses of hydrogen; Physical and chemical properties of water and heavy water; Structure, preparation, reactions and uses of hydrogen peroxide; Classification of hydrides - ionic, covalent and interstitial; Hydrogen as a fuel.
UNIT 14 S - BLOCK ELEMENTS (ALKALI AND ALKALINE EARTH METALS)
Group - 1 and 2 Elements:
General introduction, electronic configuration and general trends in physical and chemical properties of elements, anomalous properties of the first element of each group, diagonal relationships.
Preparation and properties of some important compounds - sodium carbonate, sodium chloride, sodium hydroxide and sodium hydrogen carbonate; Industrial uses of lime, limestone, Plaster of Paris and cement; Biological significance of Na, K, Mg and Ca.
UNIT 15 P - BLOCK ELEMENTS
Group - 13 to Group 18 Elements
General Introduction: Electronic configuration and general trends in physical and chemical properties of elements across the periods and down the groups; unique behaviour of the first element in each group.
Groupwise study of the p–block elements Group-13:
Preparation, properties and uses of boron and aluminium; Structure, properties and uses of borax, boric acid, diborane, boron trifluoride, aluminium chloride and alums.
Group - 14:
Tendency for catenation; Structure, properties and uses of allotropes and oxides of carbon, silicon tetrachloride, silicates, zeolites and silicones.
Group - 15:
Properties and uses of nitrogen and phosphorus; Allotrophic forms of phosphorus; Preparation, properties, structure and uses of ammonia, nitric acid, phosphine and phosphorus halides, (PCl3, PCl5); Structures of oxides and oxoacids of nitrogen and phosphorus.
Group - 16:
Preparation, properties, structures and uses of dioxygen and ozone; Allotropic forms of sulphur; Preparation, properties, structures and uses of sulphur dioxide, sulphuric acid (including its industrial preparation); Structures of oxoacids of sulphur.
Group - 17:
Preparation, properties and uses of chlorine and hydrochloric acid; Trends in the acidic nature of hydrogen halides; Structures of Interhalogen compounds and oxides and oxoacids of halogens.
Group -18:
Occurrence and uses of noble gases; Structures of fluorides and oxides of xenon.
UNIT 16 d – and f – BLOCK ELEMENTS
Transition Elements :
General introduction, electronic configuration, occurrence and characteristics, general trends in properties of the first row transition elements - physical properties, ionization enthalpy, oxidation states, atomic radii, colour, catalytic behaviour, magnetic properties, complex formation, interstitial compounds, alloy formation; Preparation, properties and uses of K2Cr2O7 and KMnO4.
Inner Transition Elements :
Lanthanoids :
Electronic configuration, oxidation states, chemical reactivity and lanthanoid contraction.
Actinoids :
Electronic configuration and oxidation states.
UNIT 17 CO-ORDINATION COMPOUNDS
Introduction to co-ordination compounds, Werner’s theory; ligands, co-ordination number, denticity, chelation; IUPAC nomenclature of mononuclear co-ordination compounds, isomerism; Bonding-Valence bond approach and basic ideas of Crystal field theory, colour and magnetic properties; Importance of co-ordination compounds (in qualitative analysis, extraction of metals and in biological systems).
UNIT 18 ENVIRONMENTAL CHEMISTRY
Environmental pollution: Atmospheric, water and soil.
Atmospheric pollution: Tropospheric and stratospheric
Tropospheric pollutants: Gaseous pollutants: Oxides of carbon, nitrogen and sulphur, hydrocarbons; their sources, harmful effects and prevention; Green house effect and Global warming; Acid rain;Particulate pollutants: Smoke, dust, smog, fumes, mist; their sources, harmful effects and prevention.
Stratospheric pollution: Formation and breakdown of ozone, depletion of ozone layer - its mechanism and effects.
Water Pollution: Major pollutants such as, pathogens, organic wastes and chemical pollutants; their harmful effects and prevention.
Soil pollution: Major pollutants such as: Pesticides (insecticides,. herbicides and fungicides), their harmful effects and prevention.Strategies to control environmental pollution.
Section-C
Organic Chemistry
UNIT 19 Purification and Characterisation of Organic Compounds
Purification (crystallization, sublimation, distillation, differential extraction, chromatography- principles and their applications).
Qualitative analysis - detection of nitrogen, sulphur, phosphorus and halogens.
Quantitative analysis (basic principles only) – estimation of carbon, hydrogen, nitrogen, halogens, sulphur, phosphorus(basic principles only)
Calculations of empirical formula and molecular formula.
Numerical problems in organic quantitative analysis.
UNIT 20 SOME BASIC PRINCIPLES OF ORGANIC CHEMISTRY
Tetravalency of carbon; Shapes of simple molecules - hybridization (s and p); Classification of organic compounds based on functional groups: - C = C - , - C ? C - and those containing halogens, oxygen, nitrogen and sulphur; Homologous series; Isomerism - structural and stereoisomerism.
Nomenclature (Trivial and IUPAC)
Covalent bond fission: Homolytic and heterolytic: free radicals, carbocations and carbanions; stability of carbocations and free radicals, electrophiles and nucleophiles.
Electronic displacement in a covalent bond: Inductive effect, electromeric effect, resonance and hyperconjugation.
Common types of organic reactions - Substitution, addition, elimination and rearrangement.
UNIT 21 HYDROCARBONS
Classification, isomerism, IUPAC nomenclature, general methods of preparation, properties and reactions:
Alkanes - Conformations: Sawhorse and Newman projections (of ethane); Mechanism of halogenation of alkanes.
Alkenes - Geometrical isomerism; Mechanism of electrophilic addition: addition of hydrogen, halogens, water, hydrogen halides (Markownikoff’s and peroxide effect); Ozonolysis, oxidation, and polymerization.
Alkynes - Acidic character; Addition of hydrogen, halogens, water and hydrogen halides; Polymerization.
Aromatic hydrocarbons - Nomenclature, benzene - structure and aromaticity; Mechanism of electrophilic substitution: halogenation, nitration, Friedel – Craft’s alkylation and acylation, directive influence of functional group in mono-substituted benzene.
UNIT 22 ORGANIC COMPOUNDS CONTAINING HALOGENS
General methods of preparation, properties and reactions; Nature of C-X bond; Mechanisms of substitution reactions.
Uses; Environmental effects of chloroform, iodoform, freons and DDT.
UNIT 23 ORGANIC COMPOUNDS CONTAINING OXYGEN
General methods of preparation, properties, reactions and uses.
ALCOHOLS, PHENOLS AND ETHERS:
Alcohols: Identification of primary, secondary and tertiary alcohols; mechanism of dehydration.
Phenols: Acidic nature, electrophilic substitution reactions: halogenation, nitration and sulphonation, Reimer - Tiemann reaction.
Ethers: Structure.
Aldehyde and Ketones: Nature of carbonyl group;
Nucleophilic addition to >C=O group, relative reactivities of aldehydes and ketones; Important reactions such as - Nucleophilic addition reactions (addition of HCN, NH3 and its derivatives), Grignard reagent; oxidation; reduction (Wolff Kishner and Clemmensen); acidity of ? - hydrogen, aldol condensation, Cannizzaro reaction, Haloform reaction; Chemical tests to distinguish between aldehydes and Ketones.
Carboxylic Acids: Acidic strength and factors affecting it.
UNIT 24 Organic Compounds Containing Nitrogen
General methods of preparation, properties, reactions and uses.
Amines: Nomenclature, classification, structure, basic character and identification of primary, secondary and tertiary amines and their basic character.
Diazonium Salts: Importance in synthetic organic chemistry.
UNIT 25 POLYMERS
General introduction and classification of polymers, general methods of polymerization - addition and condensation, copolymerization; Natural and synthetic rubber and vulcanization; some important polymers with emphasis on their monomers and uses - polythene, nylon, polyester and bakelite.
UNIT 26 BIO MOLECULES
General introduction and importance of biomolecules.
CARBOHYDRATES - Classification: aldoses and ketoses; monosaccharides (glucose and fructose), constituent monosaccharides of oligosacchorides (sucrose, lactose, maltose) and polysaccharides (starch, cellulose, glycogen).
PROTEINS - Elementary Idea of ? - amino acids, peptide bond, polypeptides; Proteins: primary, secondary, tertiary and quaternary structure (qualitative idea only), denaturation of proteins, enzymes.
VITAMINS - Classification and functions.
NUCLEIC ACIDS - Chemical constitution of DNA and RNA.
Biological functions of nucleic acids.
UNIT 27 CHEMISTRY IN EVERYDAY LIFE
Chemicals in medicines: Analgesics, tranquilizers, antiseptics, disinfectants, antimicrobials, antifertility drugs, antibiotics, antacids, antihistamins - their meaning and common examples.
Chemicals in food: Preservatives, artificial sweetening agents - common examples.
Cleansing agents: Soaps and detergents, cleansing action.
UNIT 28 PRINCIPLES RELATED TO PRACTICAL CHEMISTRY
► Detection of extra elements (N,S, halogens) in organic compounds; Detection of the following functional groups: hydroxyl (alcoholic and phenolic), carbonyl (aldehyde and ketone), carboxyl and amino groups in organic compounds.
► Chemistry involved in the preparation of the following:
Inorganic compounds: Mohr’s salt, potash alum.
Organic compounds: Acetanilide, p-nitroacetanilide, aniline yellow, iodoform.
► Chemistry involved in the titrimetric excercises - Acids bases and the use of indicators, oxalic-acid vs KMnO4, Mohr’s salt vs KMnO4.
► Chemical principles involved in the qualitative salt analysis:
Cations - Pb2+ , Cu2+, AI3+, Fe3+, Zn2+, Ni2+, Ca2+, Ba2+, Mg2+, NH4+.
Anions- CO32-, S2-, SO42-, NO2-, NO3-, CI-, Br, I. (Insoluble salts excluded).
► Chemical principles involved in the following experiments:
1 Enthalpy of solution of CuSO4
2 Enthalpy of neutralization of strong acid and strong base.
3 Preparation of lyophilic and lyophobic sols.
4 Kinetic study of reaction of iodide ion with hydrogen peroxide at room temperature.
http://www.indiaresults.com/delhi/CBSE/AIEEE-2008/syllabus-of-examination.htm
UNIT 1 SOME BASIC CONCEPTS IN CHEMISTRY
Matter and its nature, Dalton’s atomic theory; Concept of atom, molecule, element and compound; Physical quantities and their measurements in Chemistry, precision and accuracy, significant figures, S.I. Units, dimensional analysis; Laws of chemical combination; Atomic and molecular masses, mole concept, molar mass, percentage composition, empirical and molecular formulae; Chemical equations and stoichiometry.
UNIT 2 STATES OF MATTER
Classification of matter into solid, liquid and gaseous states.
Gaseous State:
Measurable properties of gases; Gas laws - Boyle’s law, Charle’s law, Graham’s law of diffusion, Avogadro’s law, Dalton’s law of partial pressure; Concept of Absolute scale of temperature; Ideal gas equation, Kinetic theory of gases (only postulates); Concept of average, root mean square and most probable velocities; Real gases, deviation from Ideal behaviour, compressibility factor, van der Waals equation, liquefaction of gases, critical constants.
Liquid State:
Properties of liquids - vapour pressure, viscosity and surface tension and effect of temperature on them (qualitative treatment only).
Solid State:
Classification of solids: molecular, ionic, covalent and metallic solids, amorphous and crystalline solids (elementary idea); Bragg’s Law and its applications; Unit cell and lattices, packing in solids (fcc, bcc and hcp lattices), voids, calculations involving unit cell parameters, imperfection in solids; Electrical, magnetic and dielectric properties.
UNIT 3 ATOMIC STRUCTURE
Discovery of sub-atomic particles (electron, proton and neutron); Thomson and Rutherford atomic models and their limitations; Nature of electromagnetic radiation, photoelectric effect; Spectrum of hydrogen atom, Bohr model of hydrogen atom - its postulates, derivation of the relations for energy of the electron and radii of the different orbits, limitations of Bohr’s model; Dual nature of matter, de-Broglie’s relationship, Heisenberg uncertainty principle. Elementary ideas of quantum mechanics, quantum mechanical model of atom, its important features, * and *2, concept of atomic orbitals as one electron wave functions; Variation of * and * 2 with r for 1s and 2s orbitals; various quantum numbers (principal, angular momentum and magnetic quantum numbers) and their significance; shapes of s, p and d - orbitals, electron spin and spin quantum number; Rules for filling electrons in orbitals – aufbau principle, Pauli’s exclusion principle and Hund’s rule, electronic configuration of elements, extra stability of half-filled and completely filled orbitals.
UNIT 4 CHEMICAL BONDING AND MOLECULAR STRUCTURE
Kossel: Lewis approach to chemical bond formation, concept of ionic and covalent bonds.
Ionic Bonding: Formation of ionic bonds, factors affecting the formation of ionic bonds; calculation of lattice enthalpy.
Covalent Bonding: Concept of electronegativity, Fajan’s rule, dipole moment; Valence Shell Electron Pair Repulsion (VSEPR) theory and shapes of simple molecules.
Quantum mechanical approach to covalent bonding: Valence bond theory - Its important features, concept of hybridization involving s, p and d orbitals; Resonance.
Molecular Orbital Theory: Its important features, LCAOs, types of molecular orbitals (bonding, antibonding), sigma and pi-bonds, molecular orbital electronic configurations of homonuclear diatomic molecules, concept of bond order, bond length and bond energy.
Elementary idea of metallic bonding. Hydrogen bonding and its applications.
UNIT 5 CHEMICAL THERMODYNAMICS
Fundamentals of thermodynamics: System and surroundings, extensive and intensive properties, state functions, types of processes.
First law of thermodynamics - Concept of work, heat internal energy and enthalpy, heat capacity, molar heat capacity; Hess’s law of constant heat summation; Enthalpies of bond dissociation, combustion, formation, atomization, sublimation, phase transition, hydration, ionization and solution.
Second law of thermodynamics- Spontaneity of processes; DS of the universe and DG of the system as criteria for spontaneity, DGo (Standard Gibbs energy change) and equilibrium constant.
UNIT 6 SOLUTIONS
Different methods for expressing concentration of solution - molality, molarity, mole fraction, percentage (by volume and mass both), vapour pressure of solutions and Raoult’s Law - Ideal and non-ideal solutions, vapour pressure - composition, plots for ideal and non-ideal solutions; Colligative properties of dilute solutions - relative lowering of vapour pressure, depression of freezing point, elevation of boiling point and osmotic pressure; Determination of molecular mass using colligative properties; Abnormal value of molar mass, van’t Hoff factor and its significance.
UNIT 7 EQUILIBRIUM
Meaning of equilibrium, concept of dynamic equilibrium.
Equilibria involving physical processes: Solid -liquid, liquid - gas and solid - gas equilibria, Henry’s law, general characterics of equilibrium involving physical processes.
Equilibria involving chemical processes: Law of chemical equilibrium, equilibrium constants (Kp and Kc) and their significance, significance of DG and DGo in chemical equilibria, factors affecting equilibrium concentration, pressure, temperature, effect of catalyst; Le Chatelier’s principle.
Ionic equilibrium: Weak and strong electrolytes, ionization of electrolytes, various concepts of acids and bases (Arrhenius, Br?nsted - Lowry and Lewis) and their ionization, acid - base equilibria (including multistage ionization) and ionization constants, ionization of water, pH scale, common ion effect, hydrolysis of salts and pH of their solutions, solubility of sparingly soluble salts and solubility products, buffer solutions.
UNIT 8 REDOX REACTIONS AND ELECTROCHEMISTRY
Electronic concepts of oxidation and reduction, redox reactions, oxidation number, rules for assigning oxidation number, balancing of redox reactions.
Eectrolytic and metallic conduction, conductance in electrolytic solutions, specific and molar conductivities and their variation with concentration: Kohlrausch’s law and its applications.
Electrochemical cells - Electrolytic and Galvanic cells, different types of electrodes, electrode potentials including standard electrode potential, half - cell and cell reactions, emf of a Galvanic cell and its measurement; Nernst equation and its applications; Relationship between cell potential and Gibbs’ energy change; Dry cell and lead accumulator; Fuel cells; Corrosion and its prevention.
UNIT 9 CHEMICAL KINETICS
Rate of a chemical reaction, factors affecting the rate of reactions: concentration, temperature, pressure and catalyst; elementary and complex reactions, order and molecularity of reactions, rate law, rate constant and its units, differential and integral forms of zero and first order reactions, their characteristics and half - lives, effect of temperature on rate of reactions - Arrhenius theory, activation energy and its calculation, collision theory of bimolecular gaseous reactions (no derivation).
UNIT 10 SURFACE CHEMISTRY
Adsorption- Physisorption and chemisorption and their characteristics, factors affecting adsorption of gases on solids - Freundlich and Langmuir adsorption isotherms, adsorption from solutions.
Catalysis- Homogeneous and heterogeneous, activity and selectivity of solid catalysts, enzyme catalysis and its mechanism.
Colloidal state- distinction among true solutions, colloids and suspensions, classification of colloids - lyophilic, lyophobic; multi molecular, macromolecular and associated colloids (micelles), preparation and properties of colloids - Tyndall effect, Brownian movement, electrophoresis, dialysis, coagulation and flocculation; Emulsions and their characteristics
SECTION-B
INORGANIC CHEMISTRY
UNIT 11 CLASSIFICATON OF ELEMENTS AND PERIODICITY IN PROPERTIES
Modem periodic law and present form of the periodic table, s, p, d and f block elements, periodic trends in properties of elementsatomic and ionic radii, ionization enthalpy, electron gain enthalpy, valence, oxidation states and chemical reactivity.
UNIT 12 GENERAL PRINCIPLES AND PROCESSES OF ISOLATION OF METALS
Modes of occurrence of elements in nature, minerals, ores; steps involved in the extraction of metals - concentration, reduction (chemical. and electrolytic methods) and refining with special reference to the extraction of Al, Cu, Zn and Fe; Thermodynamic and electrochemical principles involved in the extraction of metals.
UNIT 13 HYDROGEN
Position of hydrogen in periodic table, isotopes, preparation, properties and uses of hydrogen; Physical and chemical properties of water and heavy water; Structure, preparation, reactions and uses of hydrogen peroxide; Classification of hydrides - ionic, covalent and interstitial; Hydrogen as a fuel.
UNIT 14 S - BLOCK ELEMENTS (ALKALI AND ALKALINE EARTH METALS)
Group - 1 and 2 Elements:
General introduction, electronic configuration and general trends in physical and chemical properties of elements, anomalous properties of the first element of each group, diagonal relationships.
Preparation and properties of some important compounds - sodium carbonate, sodium chloride, sodium hydroxide and sodium hydrogen carbonate; Industrial uses of lime, limestone, Plaster of Paris and cement; Biological significance of Na, K, Mg and Ca.
UNIT 15 P - BLOCK ELEMENTS
Group - 13 to Group 18 Elements
General Introduction: Electronic configuration and general trends in physical and chemical properties of elements across the periods and down the groups; unique behaviour of the first element in each group.
Groupwise study of the p–block elements Group-13:
Preparation, properties and uses of boron and aluminium; Structure, properties and uses of borax, boric acid, diborane, boron trifluoride, aluminium chloride and alums.
Group - 14:
Tendency for catenation; Structure, properties and uses of allotropes and oxides of carbon, silicon tetrachloride, silicates, zeolites and silicones.
Group - 15:
Properties and uses of nitrogen and phosphorus; Allotrophic forms of phosphorus; Preparation, properties, structure and uses of ammonia, nitric acid, phosphine and phosphorus halides, (PCl3, PCl5); Structures of oxides and oxoacids of nitrogen and phosphorus.
Group - 16:
Preparation, properties, structures and uses of dioxygen and ozone; Allotropic forms of sulphur; Preparation, properties, structures and uses of sulphur dioxide, sulphuric acid (including its industrial preparation); Structures of oxoacids of sulphur.
Group - 17:
Preparation, properties and uses of chlorine and hydrochloric acid; Trends in the acidic nature of hydrogen halides; Structures of Interhalogen compounds and oxides and oxoacids of halogens.
Group -18:
Occurrence and uses of noble gases; Structures of fluorides and oxides of xenon.
UNIT 16 d – and f – BLOCK ELEMENTS
Transition Elements :
General introduction, electronic configuration, occurrence and characteristics, general trends in properties of the first row transition elements - physical properties, ionization enthalpy, oxidation states, atomic radii, colour, catalytic behaviour, magnetic properties, complex formation, interstitial compounds, alloy formation; Preparation, properties and uses of K2Cr2O7 and KMnO4.
Inner Transition Elements :
Lanthanoids :
Electronic configuration, oxidation states, chemical reactivity and lanthanoid contraction.
Actinoids :
Electronic configuration and oxidation states.
UNIT 17 CO-ORDINATION COMPOUNDS
Introduction to co-ordination compounds, Werner’s theory; ligands, co-ordination number, denticity, chelation; IUPAC nomenclature of mononuclear co-ordination compounds, isomerism; Bonding-Valence bond approach and basic ideas of Crystal field theory, colour and magnetic properties; Importance of co-ordination compounds (in qualitative analysis, extraction of metals and in biological systems).
UNIT 18 ENVIRONMENTAL CHEMISTRY
Environmental pollution: Atmospheric, water and soil.
Atmospheric pollution: Tropospheric and stratospheric
Tropospheric pollutants: Gaseous pollutants: Oxides of carbon, nitrogen and sulphur, hydrocarbons; their sources, harmful effects and prevention; Green house effect and Global warming; Acid rain;Particulate pollutants: Smoke, dust, smog, fumes, mist; their sources, harmful effects and prevention.
Stratospheric pollution: Formation and breakdown of ozone, depletion of ozone layer - its mechanism and effects.
Water Pollution: Major pollutants such as, pathogens, organic wastes and chemical pollutants; their harmful effects and prevention.
Soil pollution: Major pollutants such as: Pesticides (insecticides,. herbicides and fungicides), their harmful effects and prevention.Strategies to control environmental pollution.
Section-C
Organic Chemistry
UNIT 19 Purification and Characterisation of Organic Compounds
Purification (crystallization, sublimation, distillation, differential extraction, chromatography- principles and their applications).
Qualitative analysis - detection of nitrogen, sulphur, phosphorus and halogens.
Quantitative analysis (basic principles only) – estimation of carbon, hydrogen, nitrogen, halogens, sulphur, phosphorus(basic principles only)
Calculations of empirical formula and molecular formula.
Numerical problems in organic quantitative analysis.
UNIT 20 SOME BASIC PRINCIPLES OF ORGANIC CHEMISTRY
Tetravalency of carbon; Shapes of simple molecules - hybridization (s and p); Classification of organic compounds based on functional groups: - C = C - , - C ? C - and those containing halogens, oxygen, nitrogen and sulphur; Homologous series; Isomerism - structural and stereoisomerism.
Nomenclature (Trivial and IUPAC)
Covalent bond fission: Homolytic and heterolytic: free radicals, carbocations and carbanions; stability of carbocations and free radicals, electrophiles and nucleophiles.
Electronic displacement in a covalent bond: Inductive effect, electromeric effect, resonance and hyperconjugation.
Common types of organic reactions - Substitution, addition, elimination and rearrangement.
UNIT 21 HYDROCARBONS
Classification, isomerism, IUPAC nomenclature, general methods of preparation, properties and reactions:
Alkanes - Conformations: Sawhorse and Newman projections (of ethane); Mechanism of halogenation of alkanes.
Alkenes - Geometrical isomerism; Mechanism of electrophilic addition: addition of hydrogen, halogens, water, hydrogen halides (Markownikoff’s and peroxide effect); Ozonolysis, oxidation, and polymerization.
Alkynes - Acidic character; Addition of hydrogen, halogens, water and hydrogen halides; Polymerization.
Aromatic hydrocarbons - Nomenclature, benzene - structure and aromaticity; Mechanism of electrophilic substitution: halogenation, nitration, Friedel – Craft’s alkylation and acylation, directive influence of functional group in mono-substituted benzene.
UNIT 22 ORGANIC COMPOUNDS CONTAINING HALOGENS
General methods of preparation, properties and reactions; Nature of C-X bond; Mechanisms of substitution reactions.
Uses; Environmental effects of chloroform, iodoform, freons and DDT.
UNIT 23 ORGANIC COMPOUNDS CONTAINING OXYGEN
General methods of preparation, properties, reactions and uses.
ALCOHOLS, PHENOLS AND ETHERS:
Alcohols: Identification of primary, secondary and tertiary alcohols; mechanism of dehydration.
Phenols: Acidic nature, electrophilic substitution reactions: halogenation, nitration and sulphonation, Reimer - Tiemann reaction.
Ethers: Structure.
Aldehyde and Ketones: Nature of carbonyl group;
Nucleophilic addition to >C=O group, relative reactivities of aldehydes and ketones; Important reactions such as - Nucleophilic addition reactions (addition of HCN, NH3 and its derivatives), Grignard reagent; oxidation; reduction (Wolff Kishner and Clemmensen); acidity of ? - hydrogen, aldol condensation, Cannizzaro reaction, Haloform reaction; Chemical tests to distinguish between aldehydes and Ketones.
Carboxylic Acids: Acidic strength and factors affecting it.
UNIT 24 Organic Compounds Containing Nitrogen
General methods of preparation, properties, reactions and uses.
Amines: Nomenclature, classification, structure, basic character and identification of primary, secondary and tertiary amines and their basic character.
Diazonium Salts: Importance in synthetic organic chemistry.
UNIT 25 POLYMERS
General introduction and classification of polymers, general methods of polymerization - addition and condensation, copolymerization; Natural and synthetic rubber and vulcanization; some important polymers with emphasis on their monomers and uses - polythene, nylon, polyester and bakelite.
UNIT 26 BIO MOLECULES
General introduction and importance of biomolecules.
CARBOHYDRATES - Classification: aldoses and ketoses; monosaccharides (glucose and fructose), constituent monosaccharides of oligosacchorides (sucrose, lactose, maltose) and polysaccharides (starch, cellulose, glycogen).
PROTEINS - Elementary Idea of ? - amino acids, peptide bond, polypeptides; Proteins: primary, secondary, tertiary and quaternary structure (qualitative idea only), denaturation of proteins, enzymes.
VITAMINS - Classification and functions.
NUCLEIC ACIDS - Chemical constitution of DNA and RNA.
Biological functions of nucleic acids.
UNIT 27 CHEMISTRY IN EVERYDAY LIFE
Chemicals in medicines: Analgesics, tranquilizers, antiseptics, disinfectants, antimicrobials, antifertility drugs, antibiotics, antacids, antihistamins - their meaning and common examples.
Chemicals in food: Preservatives, artificial sweetening agents - common examples.
Cleansing agents: Soaps and detergents, cleansing action.
UNIT 28 PRINCIPLES RELATED TO PRACTICAL CHEMISTRY
► Detection of extra elements (N,S, halogens) in organic compounds; Detection of the following functional groups: hydroxyl (alcoholic and phenolic), carbonyl (aldehyde and ketone), carboxyl and amino groups in organic compounds.
► Chemistry involved in the preparation of the following:
Inorganic compounds: Mohr’s salt, potash alum.
Organic compounds: Acetanilide, p-nitroacetanilide, aniline yellow, iodoform.
► Chemistry involved in the titrimetric excercises - Acids bases and the use of indicators, oxalic-acid vs KMnO4, Mohr’s salt vs KMnO4.
► Chemical principles involved in the qualitative salt analysis:
Cations - Pb2+ , Cu2+, AI3+, Fe3+, Zn2+, Ni2+, Ca2+, Ba2+, Mg2+, NH4+.
Anions- CO32-, S2-, SO42-, NO2-, NO3-, CI-, Br, I. (Insoluble salts excluded).
► Chemical principles involved in the following experiments:
1 Enthalpy of solution of CuSO4
2 Enthalpy of neutralization of strong acid and strong base.
3 Preparation of lyophilic and lyophobic sols.
4 Kinetic study of reaction of iodide ion with hydrogen peroxide at room temperature.
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