Reaction with Ammonia

Halogenoalkanes react with ammonia to form primary amines. The halogenoalkane is heated with excess concentrated ammonia in ethanol in a sealed tube, so that the ammonia gas cannot escape.Ammonia is a nucleophile because the nitrogen atom has a lone pair. The lone pair attacks the δ+ carbon and the halide ion leaves, forming an alkylammonium ion.A second ammonia molecule then removes an H⁺ ion from the nitrogen, giving the amine and an ammonium ion. Overall: CH₃CH₂Br + 2NH₃ → CH₃CH₂NH₂ + NH₄Br.The primary amine still has a lone pair, so it can act as a nucleophile and react with more halogenoalkane to make secondary and tertiary amines. Using an excess of ammonia makes this further substitution less likely.