Question

Arrange the following in the increasing order of their basicities.
I. p - Toluidine
II. N, N - Dimethyl - p - toluidine
III. p - Nitroaniline
IV. Aniline

• A. III < IV < I < II
• B. II < IV < I < III
• C. III < II < I < IV
• D. I < IV < III < II

Answer 1

The correct option is A III < IV < I < II

N,N-Dimethyl p-toluidine is most basic whereas p-nitroaniline is least basic.
II +I effect of two Me groups of N atom and Me group at p position (+I and hyperconjugative. effects) are responsible for highest basicity.
I +I and H.C. effects of (Me) group at p position makes p-toluidine more basic than aniline.
IV (Standard) (Aniline)
III -I and -R effect of (-$N{O}_2$) group at p position are responsible for least basicity.