Question

Arrange the following in decreasing order of their basicity: 

• A. \( B>C>A \)
• B. \( B>A>C \)
• C. \( A>B>C \)
• D. \( A>C>B \)

Hint:

In amines, electron-donating groups (like -CH₃) increase basicity, while electron-withdrawing groups (like -NO₂) decrease it.

Answer 1

The Correct Option is B

The basicity of amines depends on the availability of the nitrogen lone pair for protonation. The following factors affect the basicity:
- Methylamine (B): Methyl groups are electron-donating via inductive effects, which increase the electron density on nitrogen, making it more basic.
- Aniline (A): The phenyl group in aniline withdraws electron density from the nitrogen via resonance, making it less basic than methylamine.
- Nitroaniline (C): The nitro group (-NO_2) is a strong electron-withdrawing group. It pulls electron density from the nitrogen through resonance, significantly decreasing its basicity.
Thus, the order of basicity is \( B>A>C \), and the correct answer is option (2).