(i) Carbylamine reaction : Aliphatic and aromatic primary amines on heating with chloroform and ethanolic potassium hydroxide form isocyanides or carbylamines which are foul smelling substances. Secondary and tertiary amines do not show this reaction.This reaction is known as carbylamine reaction or isocyanide test and is used as a test for primary amines.(ii) Diazotisation : The conversion of primary aromatic amines into diazonium salts is known as diazotisation.
The conversion is brought about by reacting the amine with HNO2 which is prepared in situ.(iii) Hofmann’s bromamide reaction : Primary amides when heated with Br2 and (aqueous or ethanoic solution of) NaOH lose a carbon atom and are converted to the corresponding amines. It is an example of step-down reaction.(iv) Coupling reaction : The reaction of diazonium salts with phenols and aromatic amines to form azo compounds having an extended conjugate system with both aromatic rings joined through the — N=N — bond, is called coupling reaction. In this reaction,the nitrogen atoms of the diazo group are retained in the product. The coupling with phenols takes place in mildly alkaline medium while that with amines occurs under faintly acidic conditions. For example,Coupling generally occurs at the p-position with respect to the hydroxyl or the amino group, if free, otherwise it takes place at the o-position.
(v) Ammonolysis : The process of cleavage of the C — X bond in alkyl halides by ammonia molecule is called ammonolysis. 1° amine thus obtained behaves as a nucleophile and further reacts with alkyl halide to form 2°, 3° and finally quaternary ammoniumsalt.(vi) Gabriel phthalimide synthesis : In this reaction phthalimide is converted into its potassium salt by treating it with alcoholic potassium hydroxide. Then potassium phthalimide is heated with an alkyl halide to yield an N-alkylpthalimide whichis hydrolysed to phthalic acid and primary amine by alkaline hydrolysis.This synthesis is very useful for the preparation of pure aralkyl and aliphatic primary amines. However, aromatic primary amines cannot be prepared by this method.
(vii) Acetylation : The process of introducing an acetyl group (CH3−

O ||

C

−) into a molecule is called acetylation. The reaction occurs by nucleophilic substitution. There occurs a replacement of hydrogen atom of –NH2 or >NH by the acetyl group. Common acetylating agents used are acetyl chloride and acetic anhydride.