Which of the following amine will not undergo acylation reaction?

N,N-Diethyl aniline

The correct answer is Option (3) → N,N-Diethyl aniline

Acylation occurs only in primary and secondary amines because they have N–H bond.

Tertiary amines do not undergo acylation.

Detailed Explanation

Option 1: Methylamine

Primary amine.

Contains N-H bond.

Undergoes acylation to form amide.

Option 2: Ethylamine

Primary amine.

Has N-H bond.

Undergoes acylation.

Option 3: N,N-Diethyl aniline

This is a tertiary amine.

No N-H bond present.

Hence cannot undergo acylation.

Option 4: N-Methylmethanamine

Secondary amine.

Contains N-H bond.

Undergoes acylation.