The most basic amine among the following is

Options

(a) p-toluidine
(b) o-nitroaniline
(c) p-nitroaniline
(d) 2,4-dinitroaniline

Correct Answer:

p-toluidine

Explanation:

Basicity of amines increases with the presence of electron releasing groups and decreases with the presence of electron withdrawing group. Among the give options, only p-toluidine has aniline with an electron donating -CH₃ group which, by virtue of its +I-effect, increases the electron density on N-atom and makes electrons more available for protonation. In o-nitroaniline, p-nitroaniline and 2,4-dinitroaniline, due to presence of electron withdrawing -NO₂ group, the electron density on N-atom is diminished. Thus, it is less basic. Similarly for p-fluoroaniline.