Amines
1.0 Introduction
2.0 Preparation of Amines
2.1 Nucleophilic substitution
2.2 Reduction of Nitro Compounds
2.3 Reduction of Nitriles
2.4 Reduction of Amides
3.0 Physical Properties
4.0 Basic Nature of Amines
5.0 Reactions of Amines
5.1 Reaction of ${1^ \circ }$ and ${2^ \circ }$ amines with aldehydes and ketones
5.2 Acylation Reaction
5.3 Carbylamine Reaction
5.4 Reaction with Nitrous Acid
5.5 Substitution Reactions of Aryl Diazonium Salts
5.6 Electrophilic substitution reaction of Aniline
5.5 Substitution Reactions of Aryl Diazonium Salts
2.2 Reduction of Nitro Compounds
2.3 Reduction of Nitriles
2.4 Reduction of Amides
5.2 Acylation Reaction
5.3 Carbylamine Reaction
5.4 Reaction with Nitrous Acid
5.5 Substitution Reactions of Aryl Diazonium Salts
5.6 Electrophilic substitution reaction of Aniline
Aryl diazonium salts react with a variety of reagents to form products in which $Z$ (an atom or group of atoms) replaces $N_2$, a very good leaving group.
Important reactions:
Coupling Reactions of Aryl Diazonium Salts
The second general reaction of diazonium salts is coupling. When a diazonium salt is treated with an aromatic compound that contains a strong electron-donor group, the two ring join together to form an azo compound, a compound with a nitrogen-nitrogen double bond.
These compounds are often coloured and are used as dyes. Benzene diazonium chloride reacts with phenol in which the phenol molecule at its para position is coupled with the diazonium salt to form $p$-hydroxyazobenzene.
Note:
- The diazonium salts are very good intermediates for the introduction of $–F$, $–Cl$, $–Br$, $–I$, $–CN$, $–OH$, $–NO_2$ groups into the aromatic ring.
- Aryl fluorides and iodides cannot be prepared by direct halogenation. The cyano group cannot be introduced by nucleophilic substitution of chlorine in chlorobenzene but cyanobenzene can be easily obtained from diazonium salt.
Thus, substituted aromatic compounds which cannot be prepared by direct substitution in benzene or substituted benzene can be prepared with the replacement of diazo group by other groups
