Using halogenoalkanes

• Preparing primary amines from halogenoalkanes is achieved using a one step nucleophilic substitution reaction, where the halogenoalkane is heated under pressure in a sealed container alongside ammonia gas or concentrated aqueous ammonia (ammonia dissolved in ethanol).
• The ammonia gas or concentrated aqueous ammonia acts as the nucleophile in the preparation of primary aliphatic amines using halogenoalkanes.
• The preparation of primary aliphatic amines from halogenoalkanes is not a good technique. This is because the N in the amine formed still possesses a lone pair of electrons (which can act as a nucleophile in successive reactions, forming secondary and tertiary amines, as well as ammonium salts, which aren’t the desired product).
• In the preparation of primary aliphatic amines from halogenoalkanes, an excess of ammonia can be used to limit further subsequent reactions, maximising the amount of primary amine formed.