Preparation, Properties, Reactions
Basicity of substituted anilines and aliphatic amines,
Preparation from nitro compounds,
Reaction with nitrous acid,
Azo coupling reaction of diazonium salts of aromatic amines,
Sandmeyer and related reactions of diazonium salts;
Main Topics Covered in the TMH Book
METHODS OF PREPARATION
SYNTHETIC USE OF DIAZONIUM SALT
SEPARATION OF A MIXTURE OF AMINES
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
Benzenamine - can also be written as amino benzene
Isomerism in amines
1. Chain isomerism
3. Position isomerism
4. functional isomerism
Preparation of amines
1. From alkyl halides
2. From Nitro compounds (specially mentioned in JEE syllabus)
3.From nitriles (cyanides) and isonitriles (isocyanides)
4. From amides
5. From oximes
6. from aldehydes and ketones
1. from alcohols
1. State and smell
1. Reaction with water (Basic character of amines) (specially mentioned in JEE syllabus)
2. Reaction with acids
3. Reaction with metal ions
5. Acylation (reaction with acid chlorides and acid anhydrides)
7. schiff's base formation
9. Carbalamine reaction (specially mentioned in JEE syllabus)
10. Reaction with nitrous acid (specially mentioned in JEE syllabus)
11. Reaction with Grignard reagent
12. Carbon disulphide
13. Carbonyl chloride
14. Ring substitution in aromatic amines
15. coupling of diazonium salts (specially mentioned in JEE syllabus)
Sandmeyer and related reactions (specially mentioned in JEE syllabus)
The diazonium salts have the general formula ArN2+X-, where X- may be an anion like Cl-, Br- etc.
The group N2+ (-N≡N+) is called diazonium ion group.
Sandmeyer reaction is a substitution reaction.
In the substistution reactions, nitrogen of the salts is lost as N2 and different groups are introduced in its place.
Various substitution reactions of diazonium salts
1. Replacement by -OH group. By boiling or by steam boiling. Phenol is formed
2. Replacement by hydrogen. By treatment with hypophophorous acid. Benzene is obtained.
3. Replacement by Cl and Br group.When the salt is warmed with cuprous chloride or cuprous bromide the corresponding halide is formed. This reaction is called Sandmeyer reaction
Past JEE Questions
How will you convert 4-nitroaniline to 1,2,3-tribromobenzene? 1990
Identify A, B and c in the following reactions
C6H5COOH + PCl5--->A
A + NH3---> B
C6H5CN +(H2, Ni)--->C
Some of the reactants can be catalysts.
How will you synthesize benzamide from nitrobenzene.
How will you prepare m-bromoiodo benzene from benzene?
Write the structures of two products of the reaction.
CH3CONHC6H5 (Br2,Fe) ---->
Arrange the following in the decreasing order of basic character
Methylamine, dimethylamine, aniline, N-methylaniline
How would you bring about conversion of Aniline to Benzylamine.
Aspartame an artificial sweetener, is a peptide and has the following structure.
(Structure not given here by me)
i) Identify the four functional groups.
ii) Write the zwitter ionic structure
iii) Write the structures of the amino acids obtained from the hydrolysis of aspartame.
iv) Which of the two amino acids is more hydrophobic?
Notes on the Classification, Structure and Nomenclature-naming of Organic compounds containing Nitrogen