Question

Which of the following groups increases the basic strength of substituted aniline?

• A. \(-\mathrm{SO_3}\)
• B. \(-\mathrm{OCH_3}\)
• C. \(-\mathrm{NO_2}\)
• D. \(-\mathrm{CN}\)

Hint:

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

Answer 1

The Correct Option is B

Step 1: Understand basicity of aniline.
The basic strength of aniline depends on the availability of the lone pair of electrons on the nitrogen atom for protonation.
Step 2: Effect of substituents.
Electron-donating groups increase the electron density on the nitrogen atom through resonance or inductive effects, thereby increasing basicity.
Electron-withdrawing groups decrease basicity by pulling electron density away.
Step 3: Analyze the given groups.
\(-\mathrm{OCH_3}\) is an electron-donating group due to its \(+R\) effect, which increases the basic strength of aniline.
\(-\mathrm{SO_3}\), \(-\mathrm{NO_2}\), and \(-\mathrm{CN}\) are electron-withdrawing groups and decrease basicity.
Step 4: Conclusion.
Thus, the group that increases the basic strength of substituted aniline is \(-\mathrm{OCH_3}\).