When an alkyl or benzyl hallide allowed to react with an ethanolic solution of ammonia, it undergoes nucleophilic substitution reaction in which the halogen atom is replaced by amino (-NH₂ group) The process of cleavage of the C-X bond by ammonia is called Ammonolysis.

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

Though primary amine is produced as the major product, this process produces a mixture of primary, secondary and tertiary amines and also quaternary ammonium salts as shown below:

This method cannot be used for the preparation of arylamines (aniline) since aryl halides are much less reactive than alkyl halides towards nucleophilic substitution reaction.

Note: Nucleophilic substitution reaction is the reaction of an electron pair donor (Nu, the nucleophile) with the electron pair acceptor (the electrophile) For example: