The amine which will not undergo benzoylation in alkaline medium is
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → N,N-Dimethylaniline
Benzoylation replaces a hydrogen atom on nitrogen by the benzoyl group, so the amine needs at least one N–H bond.
Option (1) Methanamine — Undergoes benzoylation (primary). It has two N–H bonds and gives N-methylbenzamide.
Option (2) N-Ethylethanamine — Undergoes benzoylation (secondary). Diethylamine has one N–H bond and gives N,N-diethylbenzamide.
Option (3) Benzenamine — Undergoes benzoylation (primary). Aniline gives N-phenylbenzamide (benzanilide).
Option (4) N,N-Dimethylaniline — Does not undergo benzoylation (tertiary, no N–H). Its nitrogen carries a phenyl and two methyl groups and no hydrogen, so there is nothing to replace.
NCERT (2026-27 edition):
Acylation
