34.1.1—Preparation of primary and secondary amines

Primary and secondary amines can be prepared by nucleophilic substitution of halogenoalkanes with ammonia or a primary amine, and by reducing suitable nitrogen-containing compounds such as nitriles or amides where specified.

The nitrogen substituent count determines the product: ammonia gives a primary amine after one alkylation, while a primary amine can give a secondary amine. Excess amine helps limit further substitution.

Bromoethane + excess NH₃ → ethylamine; ethylamine + bromoethane can then form diethylamine if further substitution is allowed.

Using ammonia does not guarantee only one product unless conditions control successive alkylation; primary, secondary and tertiary amines can form.