(i) Carbylamine reaction

Carbylamine reaction is used as a test for the identification of primary amines.

When aliphatic and aromatic primary amines are heated with chloroform and ethanolic potassium hydroxide, carbylamines (or isocyanides) are formed.
These carbylamines have very unpleasant odours. Secondary and tertiary amines do not respond to this test. 
The reaction is as follows:

RNH₂ + CHCl₃ + 3KOH(alc.) → RNC + 3KCl + 3H₂O

For example,
CH₃ - NH₂ + CHCl₃ + 3KOH(alc.) → CH₃ - NC + 3KCl + 3H₂O

(ii) Diazotisation

Aniline and its derivative react with nitrous acid (prepared in situ from NaNO₂ and a mineral acid such as HCl) at low temperatures (273-278 K) to form diazonium salts.
This conversion of aromatic primary amines into diazonium salts is known as diazotization.
The reaction is as follows:

(iii) Hoffmann bromamide reaction

When an amide is treated with bromine in an aqueous or ethanolic solution of sodium hydroxide, a primary amine with one carbon atom less than the original amide is produced.

This degradation reaction is known as the Hoffmann bromamide reaction.

This reaction involves the migration of an alkyl or aryl group from the carbonyl carbon atom of the amide to the nitrogen atom.
For example,

(iv) Coupling reaction

The reaction of joining two aromatic rings through the −N=N−bond is known as a coupling reaction. Arenediazonium salts such as benzene diazonium salts react with phenol or aromatic amines to form colored azo compounds.

The reaction is as follows:

It can be observed that the para-positions of phenol and aniline are coupled with the diazonium salt. This reaction proceeds through electrophilic substitution.

(v) Ammonolysis

When an alkyl or benzyl halide is allowed to react with an ethanolic solution of ammonia, it undergoes a nucleophilic substitution reaction in which the halogen atom is replaced by an amino (−NH₂) group. This process of cleavage of the carbon-halogen bond is known as ammonolysis. The reaction is as follows:

When this substituted ammonium salt is treated with a strong base such as sodium hydroxide, the amine is obtained.

(vi) Acetylation

Acetylation (or ethanoylation) is the process of introducing an acetyl group into a molecule.

Aliphatic and aromatic primary and secondary amines undergo acetylation reaction by nucleophilic substitution when treated with acid chlorides, anhydrides, or esters.
This reaction involves the replacement of the hydrogen atom of −NH₂ or > NH group by the acetyl group, which in turn leads to the production of amides.

To shift the equilibrium to the right-hand side, the HCl formed during the reaction is removed as soon as it is formed.

This reaction is carried out in the presence of a base (such as pyridine) which is stronger than the amine.

The reaction is as follows:

When amines react with benzoyl chloride, the reaction is also known as benzoylation. For example,

(vii) Gabriel phthalimide synthesis

Gabriel phthalimide synthesis is a very useful method for the preparation of aliphatic primary amines. It involves the treatment of phthalimide with ethanolic potassium hydroxide to form potassium salt of phthalimide.

This salt is further heated with an alkyl halide, followed by alkaline hydrolysis to yield the corresponding primary amine.
The reaction is as follows: