Question

Among the following amines, which one has the highest $p{k}_b$ value in aqueous solution?

• A. Methanamine
• B. N,N-Dimethylaniline
• C. Ethanamine
• D. Benzenamine

Answer 1

The correct option is D Benzenamine

Aliphatic amines (i.e, methanamine, ethanamine) are generally more basic than benzenamine (aniline). Further, due to the presence of two $C{H}_3$ groups on $N$ in N,N-dimethylaniline, it is more basic than aniline or benzenamine. Hence, benzenamine is the weakest base and hence has the highest $p{k}_b$ value.