Question

Choose the most appropriate options. Arrange the following in the decreasing order of basic character: I. p-toluidine II. N,N-dimethyl-p-toluidine III. p-nitroaniline IV. Aniline

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

Hint:

Electron-donating groups increase basicity, while electron-withdrawing groups decrease basicity.

Answer 1

The Correct Option is C

The basicity of aniline derivatives decreases as electron-withdrawing groups like NO2 (in p-nitroaniline) decrease the electron density on the nitrogen atom. On the other hand, electron-donating groups like methyl (in p-toluidine) and dimethyl groups (in N,N-dimethyl-p-toluidine) increase the electron density, enhancing the basicity. Hence, the order of basicity is: \[ {N,N-dimethyl-p-toluidine (II)}>{p-toluidine (I)}>{aniline (IV)}>{p-nitroaniline (III)} \]