The correct order of decreasing basic strength of the given amines is:

Question

The correct order of decreasing basic strength of the given amines is:

1. A. N-methylaniline benzenamine ethanamine N-ethylethanamine
2. B. N-ethylethanamine ethanamine benzenamine N-methylaniline
3. C. N-ethylethanamine ethanamine N-methylaniline benzenamine (Correct answer)
4. D. benzenamine ethanamine N-methylaniline N-ethylethanamine

Correct Answer

Option C — N-ethylethanamine ethanamine N-methylaniline benzenamine

Detailed Solution & Explanation

The correct answer is N-ethylethanamine > ethanamine > N-methylaniline > benzenamine.

Key Points

• Lower the p$K_b$, higher the basicity; aliphatic amines are stronger bases than aromatic amines (whose lone pair is delocalised into the ring).
• Among aliphatic: N-ethylethanamine (secondary, 2 +I groups) > ethanamine (primary).
• Among aromatic: N-methylaniline (an electron-donating methyl on N) > benzenamine (aniline).
• Overall order of basic strength: N-ethylethanamine > ethanamine > N-methylaniline > benzenamine.