Question

Which of the following is more basic than aniline?
A. Diphenylamine
B. Triphenylamine
C. p-nitroaniline
D. Benzylamine

Answer 1

Hint:
We know that the aliphatic amines have more basic character than aromatic amines, the basicity of amines due to the nitrogen of the amine donating its lone pair of electrons. In aromatic amines, this lone pair is in conjugation with the aromatic ring.

Complete step by step solution
Aliphatic amines have an alkyl group attached to the amino group. Alkyl groups are electron donating groups due to which they increase the electron density on the N-atom. As the result, the basicity increases. In aromatic amines, the phenyl group is an electron withdrawing group and it decreases the electron density on the N-atom. Consequently, the basicity decreases.

In case of aniline, the amino group is directly attached to the benzene ring. Hence, lone pairs on nitrogen are involved in resonance, thus less available for donation. Thus, aniline is weakly basic, but stronger than benzylamine. In case of benzylamine, \[{\rm{N}}{{\rm{H}}_{\rm{2}}}\] group is directly attached to \[{\rm{C}}{{\rm{H}}_{\rm{2}}}\] and we know that \[{\rm{C}}{{\rm{H}}_{\rm{2}}}\] is an electron donating group. It increases the basicity of benzylamine.

Therefore, the correct answer is D.

Note:
Basicity is one of the very basic and easy concepts of chemistry. Basicity of an acid can be defined as the number of replaceable hydrogen atoms of that particular acid by a base.