Thursday, September 27, 2007

Saturday, September 22, 2007

Questions and Answers Ch. 27 Aldehydes and Ketones

1. what are aldehydes?

They contain carbonyl group C=O as functional group and the carbonyl atom carries at least one H atom.

2. what are ketones?

In ketones, also carbonyl group C=O is the functional group. nut the carbonyl carbon does not contain any H atoms, but it is attached to two alkyl or aryl groups.

3. What is Gatterman reaction?

The Gattermann rection, 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.


4. How do you reduce R-COCl to an aldehyde?

By catalytic hydrogenation in the presenceof 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.

5. How do you get an aldehyde from methylbenzene?

by oxidation
6. How do you get ketone from alcohols?

By oxidation of secondary alcohols

7. What is the state of formalehyde as room temperature?

8. What is formalin?

9. Can you easily oxidize ketones?
10. Can you reduce aldehydes?
11. Can you reduce ketones?
12. What is Clemmensen reduction?
13. What is Wolff-Kishner reduction?
14. What is Cannizzaro reaction?
15. What is tollens reagent?
16.What is Fehling's solution?
17. What is Diels-Alder Reaction
18. What is Keto-Enol Tautomerism?
19 How do you get cyanohydrin from a ketone?
20. Give an example of aldol condensation.

Questions and Answers Ch. 28 Carboxylic Acids

1. what is a carboxylic acid?

These compounds have a carbonyl group and a hydroxyl group.

2. How do you prepare a carboxylic acid from primary alcohol?

3. How do you prepare carboxylic acid from alkylbenzene?

4. How do you prepare carboxylic acid from Grignard reagent?

to solid CO-2, a Grignard reagent like methyl magnesium iodide in dry ether is added. the magnesium salt of the acid formed is hydrolysed by dilute mineral acid which gives carboxylic acid.

5. How do you prepare carboxylic acid from nitriles?

by boiling them with dilute mineral acid of alkali

6. Do the molecules of carboxylic acids exhibit hydrogen bonding?

7. Why is the boiling point of caroxylic acid higher than that of an alcohol of comparable molar mass?

8. why acqueous solutions of caroxylate salts are slightly alkaline?

9. How do you convert carboxylic acid into an ester?

Heat with an alcohol in presence of dehydrating aent like concentrated sulphuric acid.

10. How do you convert carboxylic acid into acid chloride?

11. How do you convert carboxylic acid into alcohol?

12. what is Hell-Volhard-Zelinsky reaction?

13. Explain how do you get alkane from sodium salt of carboxylic acid with an example.

14. what happens when you heat a calcium salt of carboxylic acid?

15. How do you get acetic anhydride?

Acetic acid is distilled with P-2O-5 or a strong dehydrating agent.

16. What do you get from treatment of an ester with LiAIH-4 followed by acid hydrolysis?

17. Name the reactants that produce benzophenone on heating?

18. what are the differences between acetic acid and formic acid?

19. what are the products of reaction between formic acid and concentrated sulphuric acid?
20. How do you produce acetaphenone?

21. which compound is synthesized by Hell-Volhard-Zelinsky reaction?

Answers to SQ Ch. 29 Phenols

1. What phenol?

Phenols are aromatic hydroxy compounds. In phenols, one or more hydroxyl group is directly attached to the aromatic (benzene) nucleus.

2. How is phenol prepared using benzene?

Benzene is heated with excess of concentrated sulphuric acid at about 388 K to give benzene sulphonic acid. It is neutralized with sodium hydroxide solutio, 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.

3. What is the 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.

4.How is phenol prepared using benzene sulphonic acid?
It is neutralized with sodium hydroxide solutio, 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.

5.What is the action of dilute nitirc acid on phenol?

a mixture of o-nitrophenol and p-nitrophenol is formed.

6. How is phenol prepared using chlorobenzene?

By (i) Dow's Process
(ii) Rasching process

7. What is the action of conc. nitric acid in the presence of conc. sulphuric acid on phenol?

2,4,6-trinitrophenol is formed. This is picric acid.

8. How is phenol prepared using 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.

9. What is the action of Bromine in CS-2 on phenol?

o-Bromophenol + p-Bromophenol mixture is obtained. p-Bromophenol is the major product.

10. Give a test distinguish between phenol and ethanol?

Alcohol react with metal sodium to form alkoxide, liberating hydrogen. Phenol does not react with metal sodium.

11. What is the action of conc. sulphuric acid at different temperatures on phenol?
At low temperature about 288 to 293 K, o-phenol sulphonic acid is formed.

At high temperature about 373 K, p-phenol sulphonic acid is formed.

12. How will you obtain from carbolic acid, picric acid?

Phenol is also called carbolic acid.
When phenol is treated with concentrated nitric acid in the presence of concentrated sulhuric acid, 2,4,6-trinitrophenol is formed.

13. How do you use ferric chloride to distinguish between phenol and alcohol?
alcohol does not show any colouration with FeCl-3.
Phenol give violet colouration with ferric chlordie.

14. How will you obtain 2,4,6-tribromophenol from carbolic acid?

answer same as Q 12

15. What are the differences in physical properties among p-nitrophenol, o-nitrophenol and m-nitrophenol?

o-nitrophenol has a much lower boiling point, much lower solubility in water than its isomers.

These differences occur because o-nitrophenol involves intramolecular hydrogen bonding. the boiling point os o-nitrophenol is low because it exists as a monomolecule.

the solubility of m- and p- isomers is due to their ability to form hydrogen bonding with water.


16.What is williamson synthesis?

Phenols reacting with alkyl halides to yield ethers in alkaline medium.

17. what is Fries rearrangement?

When esters of phenols are heated with AlCl-3, the acyl group migrates from the phenolic oxygen to an ortho or para position of the ring producing a ketone.

18. What is the action of nitrous acid on phenol?

Nitrous acid converts phenol to nitrosophenol.

19. What is Reimer-Tiemann reaction?

When phenol is treated with cholorom and aqueous sodium hydroxide, a -CHO group is introduced in the ring.

20. What is Schotten-baumann reaction?

The reaction of phenol with benzoyl chloride.
This will produce phenylbenzoate.

21. What do phenols liberate when treated with sodium?

Phenols do not react with sodium.
22. Are phenols soluble in sodium bicarbonate solution?

Phenols are not soluble in sodium bicarbonate solution. There are soluble in sodium hydroxide solution.

23. what happens when phenol is exposed to air?
On exposure to air it turns to pink due to oxidation.
24. What is picric acid?


25. What is cresol?
The methylphenols are cresols. Both OH and NO-2 are attached to benzene.

Thursday, September 20, 2007

Answers to SQ Ch. 30 Amines

1. What are Amines?

Amines are considered as organic derivatives of ammonia obtained by replacing one, two, or all the three hydrogen atoms of ammonia by alkyl or aryl groups.

2. How do you prepare ethylamine?

By treating ethyl iodide with alcoholic ammonia in a sealed tube under pressure at 423 K,a mixture of primary, secondary and tertiary amines along with the quaternary compound(Tetraethyl ammonium iodide) is produced and the individual compounds have to separated. The primary amine ethylamine may be obtained in a good yield by using a large excess of ammonia.

3.How will you prepare diethyl amine?

Reduction of Isocyanide using H-2/Ranye Ni or Pt, LiAlH-4 or Na, C-2H-5OH gives secondary amines.

So, reduction of ethyl isocyanide gives diethyl amine.

The method of reduction of using sodium and alcohol is called Mendius reaction.

4. How is ethyl amine prepared from nitroethane?

Nitroalkanes on heating with metals like tin,iron, or zinc and concentrated hydrochloric or sulphuric acid get reduced to primary amine. Similar reduction can also be brought about by heating the nitroalkane with hydrogen in presence of finely divided nickel catalyst.

Hence ethyl amine can be prepared from nitroethane by either way. Producing nascent hydrogen through reaction between metal and acid and then reaction between nascent hydrogen and nitroethane (C-2H-5NO-2) or by heating it with hydrogen in presence of finely divided nickel.

5. How will you prepare ethyl amine from acetaldoxime?

The nascent hydrogen liberated by the action of metal sodium on ethanol reacts with acetaldoxime (CH-3CH=NOH) and gives ethylamine.

6. How will you prepare ethalamine from methyl cyanide?

Methyl cyanide on reaction with the nascent hydrogen liberated by the action of metal sodium on ethanol gives ethylamine.

7. How do you distinguish primary, secondary and tertiary amines?

Primary amines when treated with nitrous acid give alcohols evolving nitrogen gas.
Secondary amines give oily nitroso compounds.
Tertiary amines do not react at all.

8. What are the Differences between primary, secondary and tertiary amines?

9. What is the action of acetyl chloride on primary amines?
acetal derivatives are formed. By using excess of acetyl chloride diacetyl derivatives can be formed.
10. What is the action of sodium nitrite and hydrochloric acid on ethyl amine?

Ethanol, nitrogen and water are formed.

11. what is the action of nitrous acid in dimethyl amine?(1981 IIT MCQ)

an oily nitroso compound N-Nitroso diethyl amine and water are formed.

12. Give the structure of 2-propanamine.

13. What is methylation of amines?

It is a reaction in which, H-atoms of an amine are replaced by methyl (-CH-3)groups. Methylation can be carried out by treating an amine with a methylating agent such as methyl halid, like methyl iodide.

14. What is the action of acetic anhydride on Triethyl amine?

Tertiary amines do not react with acetic anhydride.

15. What is carbalamine test? (1984, IIT MCQ)

The treatment of a primary amine with chloroform and alcoholic potash produces carbylamine (isocyanide) which has most offensive smell.
This reaction is not exhibited by secondary and tertiary amines.

16. what is Libermann reaction?

It is the reaction of secondary amine with nitrous acid in which nitrosoamine is formed.

17. what is Gatttermann reaction?

Diazonium salt is treated with copper powder and hydrogen halide. The halogen gets introduced into aromatic ring.

18. What is Hinsberg reagent?


19. what is Hoffmann's degradation method?(1983, IIT MCQ)

Primary amines can be prepared from amides by reduction with LiAlH-4 or by treating with Br-2 and NaOH. The reduction with LiAlH-4 gives amine having the same number of C atoms as the original amide while reduction with NaOH and Br-2 gives amine having one carbon atom less than the original amide.

20. What is aniline?

Aniline is benzenamine. one H in NH-3 is replaced benzoil group.

21. How do you prepare diazonium salt?

Primary aromatic amine n cold acqueous mineral acid + sodium nitrite

22. What is sandmeyer reaction?

The diazonium salt is treated with cuprous chloride or cuprous bromide.

23. How do you prepare chlorobenzene? (1984, MCQ)

Sandmeyer reaction or Gattermann reaction. In these chlorine is introduced into benezene ring.

24. What is the effect of alkyl groups C-3H-7, C-2H5 and CH-3 on the basic nature of amines?

Amines are weak bases.

The effect of alkyl groups is

C-3H-7> C-2H5> CH-3

The amines are stronger bases than ammonia.

25. Among Aralkylamines and arylamines whic are more basic? (1990 MCQ)

Aralkylamines. Hence Benzylamine (phenylaminomethane) is a more stronger base than aniline.

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Wednesday, September 19, 2007

Answers to SQ Ch. 31 Carbohydrates

1. what are carbohydrates?

Carbohydrates means hydrates of carbon. They are polyhydroxy aldehydes or polyhodroxy ketones.

2. How are carbohydrates classified?

Based on their solubility in water
i) Sugars - soluble
ii)Nonsugars - insoluble ex: starch, cellulose
Bsed on their chemical constitution
i) Monosaccharides
ii) Oligosaccharides
iii) Polysaccharides

3. How is glucose prepared from sucrose?

Sucrose is hydrolysed by concentrated alcoholic solution of hydrochloric acid. the hydrolysis is carried out at about 323 K by heating on a water bath for about two hours. Glucose and fructose will be the products, glucose being almost insoluble in alcohol crystallises on cooling while fructose being comparatively more soluble remains in solution.

4. What are monosaccharides?

These are basic units of carbohydrates and cannot be hydrolized to simpler compounds.
5. give an example of polysaccharide.

starch, cellulose, insulin

6. Give an example of oligosaccharide.

Raffinsoe, stachyose

7. How many stereo isomers a carbohydrate can have?
Carbohydrates copntain asymmetric carbon atoms. They can have stereoisomers, the number of which is equal to 2 to the power of n (2^n) where n is the number of asymmetric carbon atoms in the molecule of carbohydrate.

8. What is a cyclic hemiacetal structure?


see Page 943 of Jauhar

9. What is Haworth projection?

IN this structure, a ring is shown as a plane perpendicular to the plane of the paper. The edge of the plane that would project out of the paper toward the reader is darkened to emphasize its orientation. the hydroxyl groups are then positioned above or below the plane. The hydrogen atoms are usually not shown.

10. What is Fischer projection?

In Fischer projection formula, the carbon chains is positioned vertically with the substituents drawn to the right and left on the chain. The horizontal lines represent bonds coming towards the reader and the vetical lines represent bonds projected away from the reader. The aldehydic or ketonic group is placed at the top of the vertical line.

11. What is chair conformational formula?

Chair conformational formula give the accurate three-dimensinal picture of pyranose rings.

12. What are anomers?

When an open-chain monosaccharide cyclizes to a furanoes or pyranose form, a new chiral centre at the carbonyl carbon (known as anomeric carbon) is created. The two diasteromers produced are called anomers.

13. What is mutarotation?

When either alpha form or beta form of glucose is dissolved in water, alpha form changes to beta form (or vice versa) and a solution containing 36% of alpha form and 64% of beta form is obtained. The optical rotation will have a value of +52.6 degree. This phenomenon is known as mutarotation.

14. What reactions are supported by reducing sugars?

Reducing sugars are easily oxidized to give carboxylic acid. They reduce Tollens reagent to shiny silver mirror. They reduce Fehling's solution to red precipitate of cuprous oxide. They reduce Benedict's reagent to red precipitate of cuprous oxide.

15. Give two examples of disaccharides.
Lactose and Sucrose

16. What is invert sugar?


17. what are hydrates of carbon?


18. Give the structure of Ketopentose.
19. give the structure of ketotriose.
20. Give the structure of aldotetrose.

21. Give 5 sugars and rank them in relative order of sweetness.

Sucrose (100), Glucose (74), Fructose (73), Galactose (32), Maltose (32)

Answer to SQ Ch. 32 Amino Acids and Peptides Question Bank

1. What are amino acids?
Amino acids are organic compound containing both an amino group and carboxylic group. The amino group is NH-2 and the carboxyl group is COOH.

2. What is the link between amino acids and proteins?
Structurally, proteins are long polymers of amino acids linked by peptide bonds.

3. Give two examples of amino acids with Nonpolar R Group.

Glycine and Alanine (Ref TMH page 32.1)

4. Give two examples of Amino acids with Polar R Group.

Serine and Thronine (Refer TMH Page 32.2)

5. Give two examples of amino acids with charged R group.

Aspartic acid and Lysine (Ref TMH page 32.2)

6. Give two examples of amino acids that cannot be made by human body.

Phenylalanine, Tropophan (Ref TMH 32.1 or Jauhar-XII-Page 954)

7. What is chiral nature of amino acids?
Except glycine all other amino acids contain asymmetric carbon next to the carboxylic acid. So they are all chiral.

8. What is zwitterion?

In highly acidic conditions (pH = around 1), both the carboxylic group and the amino group are protonated. On increasing the pH of the solution, the carboxyl group ionizes to produce a dipolar ion. The doubly charged ion is known as zwitterion(from German meaning double ion). The pH of the ion solution at which the species becomes zwitterion is known as isoelectric point.

9. What is peptide linkage?

The condensation of two amino acids with the elimination of H-2O produces Co-NH linkage, which in protein chemistry, is known as a peptide linkage. (For explanation of condensation and elimination see polymers chapter)

10. What is a dipeptide?

It is a linkage between two amino acids

11. What is the relation between peptide and protein?

Structurally, proteins are long polymers of amino acids linked by peptide bonds.

12. What is the simplest amino acid?


Answers to Simple Questions Ch. 33 Polymers

1. What is a polymer?

Polymers are compounds of very high molecular masses formed by the combination of a large number of simple molecules. In Greek, poly means many and meros means units or parts.

2. Give two examples of natural polymers.

i) Starch ii) Celulose

3. What are homopolymers?

A polymer formed from one type of monomers is called homopolymer.

4. What are step-growth polymers?

Step growth is also called condensation polymerisation. In this type the monomers genrally contain two functional groups and the polymer is formed with the elimination of simple molecules like water, ammonia, hydrogen chloride, alcohol etc. IN this process each step is the same type of chemical reaction. Common examples are Nylon 66 and Bakelite.

5. What are chain growth polymers?

This is also called addition polymerisation. This polymerisation involves a series of reactions each of whichconsumes a reactive particles and produces anohter similar particle resulting in a chain reaction. Likeother chain reactions, this polymerisation reaction also involves an initiator whihc may be a free radical, a cation or anion.

6. What are elastomers?

The polymers that have elastic character like the rubber are called elastomers. The most important example of elastomer is natural rubber.

7. Give two examples of fibres.

Nylon 66, dacron

8. What is a thermoplastic?

These are polymers which can be easily softened repeatedly when heated and hardened when cooled with little change in their properties.

9. What is the monomer for polymer polyvinyl acetate?

Vinyl acetate

10. How do you get isomers of Poly(1,3-butadiene) from butadiene?

butadiene , colorless, gaseous hydrocarbon. There are two structural isomers of butadiene; they differ in the location of the two carbon-carbon double bonds in the butadiene molecule. One (1,2-butadiene) has the formula CH-2:C:CHCH-3 . The other (1,3-butadiene), often called simply butadiene, has the formula CH-2 :CHCH:CH-2 ; it is used in the manufacture of synthetic rubber, latex paints, and nylon and is obtained chiefly by dehydrogenation of butane and butene obtained by cracking petroleum.

11. Give two examples of copolymers.

Saran, Buna-S (a rubber)

12. What vulcanizatin of rubber?

Both natural and synthetic rubbers are soft. In vulcanisation, rubber is heated with a per cent by mass of sulphur. This results into the formation of sulphur bridges between polymer chains.

13. Give tow examples of step growth polymers.

Terylene or Dacron and Nylon-6.

14. How do you get nylon-66 polymer?

Hexamethylene diamine and Adipic acid polymerise to produce nylon-66 polymer.

15. How do you produce bakelite?

The starting materials are formaldehyde and phenol. IN the presence of a basic catalyst (OH) these two substances combine to give ortho and para hydroxymethylphenol. These materials undergo condensation to produce cross-linked polymer bakelite involving methylene bridges in ortho, para, or both ortho and para positions.

Polybutadiene can be formed from many 1,3-butadiene monomers undergoing free radical polymerization to make a much longer polymer chain molecule.

A chain propagating step in this chemical reaction involves a free radical near the end of a growing polymer chain forming a covalent bond with the #1 carbon in a 1,3-butadiene monomer molecule being added, resulting in a polymer chain intermediate with a substituted allyl free radical at the end of the chain. This allyl free radical, formed from the butadiene just added, can further bond to another monomer molecule at either the #2 or #4 carbons of the previous butadiene monomer. Most of the time, the new monomer bonds to the #4 or terminal carbon of the previous butadiene, resulting in a 1,4-addition of the previous butadiene unit. In a 1,4-addition, the two double bonds of the previous butadiene unit are turned into single bonds and a new double bond is formed between the #2 and #3 carbons. This new double bond may have either a cis or a trans configuration.

There are different catalysts available which can result in polymerization either in the cis or the trans configurations.

16. What are the monomers of Buna-S polymer?

Styrene(25%) + Butadiene (75%)

17. What do you get by polymerisation of caprolactum?

Nylon 6

18. What is monomer of teflon?


19. What is monomer of synthetic rubber?

2-methyl-1, 3-butadiene

20. What is the monomer of starch?