Question

Quaternary ammonium salt is formed:

पर्याय

• By nucleophilic substitution of primary amines

• By nucleophilic substitution of tertiary amine

• By electrophilic substitution reaction

• By nucleophilic addition reaction

Answer 1

By nucleophilic substitution of tertiary amine

Explanation:

The primary amine is obtained by nucleophilic substitution of an alkyl halide by NH₃.

\[\ce{NH3 + R - X -> R - NH2 + HX}\]

This product then behaves as a nucleophile because of a lone pair of N of RNH₂ and further reacts with an alkyl halide to form secondary and tertiary amines, and finally quaternary ammonium salt.

\[\ce{RH2 + RX -> R2NH + HX}\]

R₂NH can further act as a nucleophile and react with RX

\[\ce{R2NH + RX -> R3N + HX}\]

R₃N can further attack RX to give quaternary amine salts

\[\ce{R3N + RX = R4N^+X^-}\]

The reaction cannot go any further because now the lone pair is not present on N and its valency is filled.