Formation of Amines

This lesson covers: 

  1. How aliphatic amines are produced
  2. The reaction mechanism involved in producing aliphatic amines

Aliphatic amines form from halogenoalkanes, nitriles or amides

There are two main ways to produce aliphatic amines:

  • Nucleophilic substitution of halogenoalkanes
  • Reduction of nitriles or amides

Producing primary and secondary aliphatic amines

Primary and secondary aliphatic amines can be produced through several reactions.

Halogenoalkanes with ammonia

Aliphatic amines are produced by heating a halogenoalkane under pressure with excess ammonia in ethanol.


For example, ethylamine is produced from bromoethane:

CH3CH2Br + 2NH3 ➔ CH3CH2NH2 + NH4Br


This involves nucleophilic substitution via a two-step mechanism:

Diagram showing the nucleophilic substitution mechanism where ammonia attacks a halogenoalkane to form an alkylammonium salt and then an amine.
  1. The halogenoalkane is attacked by ammonia, displacing the halogen and forming an alkylammonium salt.
  2. A second ammonia molecule then removes a proton from the salt to form the amine product.

Halogenoalkanes with primary amines

Heating a halogenoalkane under pressure with a primary amine in ethanol in a sealed tube yields secondary amines through nucleophilic substitution.


For example, diethylamine is produced from bromoethane:

CH3CH2Br + 2CH3CH2NH2 ➔ (CH3CH2)2NH + HBr

Reducing amides with LiAlH4

Amides can be reduced by lithium aluminium hydride (LiAlH4) to produce primary amines:

RCONH2 + 4[H] ➔ RCH2NH2 + H2O

Reducing nitriles

Nitriles are reduced to primary amines using lithium aluminium hydride (LiAlH4) or catalytic hydrogenation with H2 and Ni catalyst:

R-C≡N + 4[H] ➔ R-CH2-NH2