Amines
1.0 Introduction
2.0 Preparation of Amines
2.1 Nucleophilic substitution
2.2 Reduction of Nitro Compounds
2.3 Reduction of Nitriles
2.4 Reduction of Amides
3.0 Physical Properties
4.0 Basic Nature of Amines
5.0 Reactions of Amines
5.1 Reaction of ${1^ \circ }$ and ${2^ \circ }$ amines with aldehydes and ketones
5.2 Acylation Reaction
5.3 Carbylamine Reaction
5.4 Reaction with Nitrous Acid
5.5 Substitution Reactions of Aryl Diazonium Salts
5.6 Electrophilic substitution reaction of Aniline
2.1 Nucleophilic substitution
2.2 Reduction of Nitro Compounds
2.3 Reduction of Nitriles
2.4 Reduction of Amides
5.2 Acylation Reaction
5.3 Carbylamine Reaction
5.4 Reaction with Nitrous Acid
5.5 Substitution Reactions of Aryl Diazonium Salts
5.6 Electrophilic substitution reaction of Aniline
This is a kind of substitution reaction using nitrogen nucleophiles.
- An alkyl or benzyl halide on reaction with an ethanolic solution of ammonia undergoes nucleophilic substitution reaction in which the halogen atom is replaced by an amino $(–NH_2)$ group in a sealed tube at $373\ K$. This process of cleavage of the $C–X$ bond by ammonia molecule is known as ammonolysis.
- The primary amine thus obtained behaves as a nucleophile and can further react with alkyl halide to form secondary and tertiary amines, and finally quaternary ammonium salt as shown in the reactions below.
- The major disadvantage of this reaction is yielding of a mixture of primary, secondary and tertiary amines and also a quaternary ammonium salt. However, by taking large excess of ammonia, primary amine is obtained as a major product.
- The order of reactivity of halides with amines is $$RI\ >\ RBr\ >\ RCl$$
Gabriel Synthesis Reaction of ${1^ \circ }$ Amines
It consists of two steps and uses a nucleophile derived from phthalimide to synthesize ${1^ \circ }$ amines via nucleophilic substitution as shown in the mechanism below.
Steps in Reaction Mechanism:
Note: Aromatic primary amines cannot be prepared by this method because aryl halides do not undergo nucleophilic substitution with the anion formed by phthalimide.
