Cracking AIEEE Tips from Orkut AIEEE community

http://www.orkut.com/CommMsgs.aspx?cmm=10597861&tid=2593734643528395271

ABHI: Feel the


How can u crack AIEEE


Hi everyone. I am abhishek. I cracked AIEEE last year. Now I would like to tell you all how an average student can crack AIEEE if he plans in a proper way.

Some rules to crack any comp exam..

You must have a deep knowledge of the syllabus.

You must have done deep analysis of the exam

You must have seen the changing pattern of the exam in last few years

You must have a right strategy for the exam

You must be confident to crack it

Most importantly dont panic, No one is perfect. Stay calm on the exam day....



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Now talking about AIEEE exam. Cracking AIEEE or not totally depends on time management while giving exam. For it right choice of the questions must be done so that you dont waste time on difficult question and leaving them without getting the answer and wasting 1 to 2 minutes. Remember most of the student dont clear AIEEE b'coz they make this mistake....

If you see the AIEEE 2007 paper you will find that there were 120 questions each carrying 3 marks. The total marks were 360 out of which if you had scored 200+ marks you were always safe to get a good college,. After doing a deep analysis of the last year paper I have found that in physics most of the questions were from electricity, magnetism, modern physics and mechanics.

About 75 to 80% paper was covered from these topics. 35% questions were easy and 60% were medium. So if you attempt 65% questions ie 26 questions with 4 wrong out of 40. This means your score is 76-4=72 marks. Now these 26 questions you had to do in 50 minutes. means 2 minutes for each question which is quite a fair time to solve the questions as some of the questions are conceptual. So if you can attempt your mocks by following this strategy for physics it will help you and try to implement it in your AIEEE exam...

Talking about chemistry, This is the most broad branch but scoring one,

Doing analysis of last year. Physical chemistry had 21 questions, organic 12 and inorganic 7. What this shows that physical chemistry is the most important part to crack AIEEE as the examiners love it to put it in Question paper. student also try to put too much time in doing organic and leaving Physical..

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Important topics for Physical chemistry

Atomic structure and chemical bonding 4 questions

Thermodynamics 4 questions

Equilibrium 3 questions

Nuclear chemistry and electro chemistry 2 questions each.

They consist 15 questions out of which if you are doing 12 questions out of which 10 are right.
your score for physical is 28.

Talking about Organic chemistry

Organic chemistry- basic principles 2 questions

Stereochemistry 2 questions

Hydrocarbons 2 questions

If you are attempting 10 questions in this section having 8 right. your score for this section is 22.

Talking about inorganic part. p , d and f block are most important. Still if your are sticking with these three topics, you are able to do 8 questions. Assuming your score for this section is 22.

Lets doing the total of your score for Chemistry 28+22+22=72
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Now comes the most difficult part. MATHS

Doing the analysis. I have found that calculus and algebra are the most coming topics in the previous year papers of AIEEE. Last year 20 questions were there from these two topics. If you had attempted 14 questions with 11 right and 3 wrong from these two topics. Your score was 30 in this part.And if you had spent 30 minutes for these 14 questions. you were still left with 20-25 minutes. You should had gone for 3D, vectors and cordinate geometry. These three topics had 12 questions and if you had done 8 questions in remaining 20 minutes qith 6 right. Your score for these topics was 14 making your total score for Maths 44. This is a rough calculation. Score of 50 can be easily obtained.

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So your total score in AIEEE is 72+72+50= 194 which could had easily fetched a seat in a very nice institute.


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One more important thing for you all.......

Never attempt maths first. It will surely ruin your performance in the exam.....

Try to attempt chemistry in the first hour as it has some easy questions and if you can solve these question in the first hour, you will feel confident with more accuracy,. this has been proved that if you are confident then your efficiency increases,,,,,,,,,

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inorganic and organic also cover huge part in AIEEE exam. What I think is that most important thing is how can u get through cut off. This can be done alone with organic and inorganic. As you also know that chemistry is the most scoring of all.. Do one thing just read the concepts of thermodynamics and chemical equilibrium. You can see that some questions from these parts are just conceptual type. So just clear your concepts and you can do 40% questions from these two topics.

Believe me those who crack AIEEE are those who does well in chemistry. In these coming days concentrate more on chemistry. If you are studying 10 hours a day. Study atleast 4 hours for chemistry. With in these 4 hours brush up your concepts of organic and inorganic for 3 hours and give 1 hour for physical. If after this you can do 8 questions from physical and as you said you are good in organic and inorganic then you can do better in these sections. Then surely you are clearing your Cut off for Chemistry.

Always do theoretical questions firstly and after this question which require calculation. its a nature of human that if you do few questions in the beginning then positive energy will come inside you and your efficiency will increase.....

Never attempt numerical questions in the first 10 or 15 minutes of your exam.......

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Talking about mocks. Do 5 mocks before exam. It will help you to know where are you wasting your time in doing the exam. Dude do mocks. They are most important to crack AIEEE

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Tomorrow is 18th, leaving day before AIEEE you are left with 8 days. Do one thing revise all the formulas and the important points which you have marked within these 8 days. Remember that study all three subjects everyday. I hope that you have marked important points. Make a time table for the coming six days to revise your syllabus. Time table must be like that you are giving max time to your strengths. Like if your strength in Physics is Electrostatics then revise electro giving enough time to it so that you are sure about every concept about it. If you are not sure about modern physics then whatever you have studied about it, study it. Dont study anything new about anything.

Try to cover your syllabus within next 6 days. Now you have revise your syllabus once.
On seventh day, do two mocks before night. Try to analyze where are you making mistakes, I mean where are you wasting your time. Which section you are doing best. Whatever mistakes you make in first paper try to remove in second. In this you will be better prepared for the main exam. What most students do is that they revise whole of the syllabus but never attempt a mock and thus they always make mistake in main exam and thus they loose the track..

After this at night and on 8th day again revise some important points or you can mark some important points on these six days to revise on the 8th day.

After this, on day before AIEEE dont study anything. Calm yourself, Say to yourself I am excited about AIEEE and I can crack it easily. Go to temple and play with your friends. Dont talk anything about AIEEE with others. Dont ask your friend how much they have studied. It will cause much pressure. You can even watch a film on 26th.

Then sleep for atleast 8 hours and go to your center with full confidence.

Cracking any exam depends on two things

How you study

Your attitude....

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For maths, I would recommend you R.D sharma objective. This is a very good book. Every type of questions are covered in this book.

For Physics H.C verma is best book to clear your concepts. After attempting questions from it you can take any objective book or AIEEE explorer and search for the questions in the net. There are some magzines like Physics Today which will help you in doing mocks and new questions. This is a monthly magzine which must be done. It is a very nice one.

For chemistry study NCERT book. Well I believe that chemistry portion in AIEEE is more conceptual paper than numerical, so I believe that P. Bahadur will not help you upto huge level . But still do short questions from it rather than trying big numerical from it.
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AIEEE Model paper published in eenadu 19 April 2009

http://www.eenadu.net/pratibhaplus/prati03.pdf

http://www.eenadu.net/pratibhaplus/prati04.pdf

http://www.eenadu.net/pratibhaplus/prati05.pdf

http://www.eenadu.net/pratibhaplus/prati08.pdf

http://www.eenadu.net/pratibhaplus/prati09.pdf

http://www.eenadu.net/pratibhaplus/prati10.pdf

http://www.eenadu.net/pratibhaplus/prati11.pdf

Key to the paper
http://www.eenadu.net/pratibhaplus/prati23.pdf



Model Paper II

http://www.eenadu.net/pratibhaplus/prati14.pdf

http://www.eenadu.net/pratibhaplus/prati15.pdf

http://www.eenadu.net/pratibhaplus/prati16.pdf

http://www.eenadu.net/pratibhaplus/prati17.pdf

http://www.eenadu.net/pratibhaplus/prati20.pdf

http://www.eenadu.net/pratibhaplus/prati21.pdf

http://www.eenadu.net/pratibhaplus/prati22.pdf

Key to the paper
http://www.eenadu.net/pratibhaplus/prati23.pdf

AIEEE Chemistry Unit 13 Hydrogen

UNIT 13 HYDROGEN
Position of hydrogen in periodic table, isotopes, preparation, properties and uses of hydrogen;
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Period 1 Group 1
Atomic Number 1
Symbol H
Atomic Weight 1.0079
Discovery Cavendish, 1766
Hydrogen was prepared for many years before it was recognized as a distinct element.
Electron Configuration 1s¹
Word Origin Greek: hydro, water; genes, forming
Named by Lavoisier.

Isotopes

Protium (0 neutrons), Deuterium (1 neutron), and Tritium (2 neutrons).
Properties

Hydrogen is the most abundant element in the universe.


Hydrogen is a colorless, odorless, combustible gas.

Hydrogen gas is so light and diffusive that uncombined hydrogen can escape from the atmosphere.

Hydrogen gas ordinarily is a mixture of two molecular forms, ortho- and para-hydrogen, which differ by the spins of their electrons and nuclei.
Normal hydrogen at room temperature consists of 25% of the para form and 75% of the ortho form. The ortho form cannot be prepared in the pure state. Since the two forms of hydrogen differ in energy, their physical properties also differ.


Uses

Hydrogen is important in the proton-proton reaction and carbon-nitrogen cycle. Liquid hydrogen is used in cryogenics and in the study of superconductivity.
Great quantities are used for the fixation of nitrogen from the air in the Haber ammonia process.
Hydrogen is use in welding, for the hydrogenation of fats and oils, in methanol production, in hydrodealkylation, hydrocracking, and hydrodesulfurization.
Other applications include producing rocket fuel, filling balloons, making fuel cells, producing hydrochloric acid, and reducing metallic ores.
Deuterium is used as a moderator to slow down neutrons and as a tracer.
Tritium is used in the production of the hydrogen (fusion) bomb.
Tritium is also used in making luminous paints and as a tracer.

Sources

Hydrogen occurs in the free state in volcanic gases and some natural gases. Hydrogen is prepared by steam on heated carbon, decomposition of certain hydrocarbons with heat, action of sodium or potassium hydroxide on aluminum electrolysis of water, or displacement from acids by certain metals.

AIEEE Chemistry Unit 13B Water and Heavy Water

Physical and chemical properties of water and heavy water;



Heavy water is water that contains the heavy isotope of hydrogen called deuterium (chemical symbol D). The deuterium atom weighs about twice as much as ordinary hydrogen atom. Heavy water, also called deuterium oxide, makes up about 1 part in 5000 of ordinary water.

It was first separated from ordinary water in 1932 by G N Lewis, a chemist at the University of California.

Because of the difference between the weights of the two kinds of hydrogen atoms, the physical properties of heavy water differ from those of ordinary water. Heavy water freezes at 3.82oC and boils at 101.42oC.

Ice made from heavy water sinks in normal water.

Heavy water is useful in some kinds of nuclear reactors. It acts as a moderator to control the energy of the neutrons in a chain reaction. Seeds will not germinate in heavy water, and some animals, including tadpoles, cannot live in it.

Unit 13C Hydrogen Peroxide

Structure, preparation, reactions and uses of hydrogen peroxide;


Hydrogen peroxide, H2O2, was first discovered by Thenard among others in 1818 by reacting acids with barium peroxide, BaO2.

It resembles water in appearance being colourless in small quantities but blue when observed in thick layers.

It decomposes to oxygen and water and this decomposition is promoted by heat and alkalis.

Commercial grade H2O2 usually contains small amounts of stabilizers.


Hydrogen peroxide is a strong oxidising agent and is widely used as a bleaching agent. In dilute solutions it is an efficient antiseptic. The uses of hydrogen peroxide have been changing in recent years.

Uses

Textile bleaching
Chemical production
Wood pulp bleaching - Major user
Environmental uses
Miscellaneous uses


Production process

Hydrogen peroxide is produced by reducing alkylanthraquinone with hydrogen in the presence of a catalyst to the hydroquinone. After the catalyst has been removed to prevent decomposition of the hydrogen peroxide, the hydroquinone is oxidised, usually with air, back to quinone with a resultant co-production of hydrogen peroxide.

The hydrogen peroxide is removed and purified and the quinone is regenerated and returned to the reaction.

The anthraquinone must be dissolved in a suitable solvent for the hydrogenation, oxidation and extraction steps - this is usually referred to as the working solution. The solvent is usually a mixture because quinones dissolve readily in non-polar aromatic solvents, such as alkylbenzene, whereas hydroquinones dissolve well in polar solvents, such as alcohols and esters. A variety of different mixtures are in use but the aim is to satisfy a number of criteria, namely good solubility of both quinone and hydroquinone, good stability in both hydrogenator and oxidiser, low solubility in water and aqueous hydrogen peroxide solutions, sufficiently higher or lower density than water to ensure separation of the two phases during extraction, low volatility, high distribution coefficient for hydrogen peroxide in the solvent-water system and low toxicity. 1

In the hydrogenator, the working solution is reacted with hydrogen in the presence of a catalyst. The process is exothermic and the heat of reaction is removed by cooling the working solution before it enters the hydrogenator, by cooling the reactor during hydrogenation and/or by cooling the hydrogenated working solution.

After the hydrogenation reaction, the working solution must pass through a filtration stage to remove all traces of catalyst. Even small traces of catalyst in the oxidation and extraction stages lead to significant losses of hydrogen peroxide and could present safety problems. During the oxidation stage, air is passed through the hydrogenated working solution to convert the dissolved hydroquinones to quinones and form the hydrogen peroxide. The air outlet is passed over activated carbon adsorbers to recover solvent.

Crude hydrogen peroxide is extracted from the oxidised working solution by treating with water. The working solution is then regenerated and fed back to the front of the process and the crude hydrogen peroxide (15-35 wt%) is fed to a treatment unit where the concentration is increased to 50-70 wt%.

Link for AIEEE online sample test/question papers

http://easportsfifa08.blogspot.com/2008/01/free-eamcetaieee-online-test-papers.html

I downloaded a paper.

AIEEE Chemistry Unit 14A 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,


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.

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

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.

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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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.

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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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.

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.

AIEEE Chemistry Unit 15G Group 18 Elements

Occurrence and uses of noble gases; Structures of fluorides and oxides of xenon.

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.

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;

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.

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.

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.

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).

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

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.

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

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.

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

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.

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

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

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

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

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

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.
--------------------


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

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
-----------------

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

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.

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