Question

Illustrate the following reactions giving suitable example in each case 

Acetylation of amines

Answer 1

Acetylation of amines: Acetylation is the process of introducing an acetyl group into a molecule. Aliphatic and aromatic primary and secondary amines undergo the acetylation reaction by nucleophilic substitution when treated with acid chlorides, anhydrides or esters. This reaction involves the replacement of the hydrogen atom of the −NH₂ or > NH group by the acetyl group, which, in turn, leads to the production of amides. To shift the equilibrium to the right-hand side, the HCl formed during the reaction is removed as soon as it is formed. This reaction is carried out in the presence of a base (such as pyridine), which is stronger than the amine.

For example, the reaction of benzenamine with acetyl chloride in the presence of pyridine yields N-phenylethanamide.

\[{C_6 H_5 - {NH}_2}_{Benzenamine} + {{CH}_3 - CO - Cl}_{Acetyl chloride} \to^{Pyridine} {C_6 H_5 - NH - CO - {CH}_3}_{{N - Phenylethanamide}_\left( Soluble in alkali \right)} + HCl\]