Question

The correct increasing order of basic strength for the following compounds is

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

Answer 1

The Correct Option is D

The question requires determining the increasing order of basic strength for the given compounds. The compounds are:

Let's label the compounds:

• I: Aniline (C₆H₅NH₂)
• II: p-Nitroaniline (C₆H₄NO₂NH₂)
• III: p-Toluidine (C₆H₄CH₃NH₂)

Explanation:

1. The basicity of aniline derivatives depends on the electron-donating or electron-withdrawing nature of substituents on the benzene ring.
2. p-Nitroaniline (II): The nitro group (\text{-NO}_2) is a strong electron-withdrawing group. It decreases the electron density on the nitrogen atom of the amine group, thus reducing its basicity.
3. Aniline (I): It has no substituents that significantly affect the electron density. Hence, it is more basic than p-Nitroaniline.
4. p-Toluidine (III): The methyl group (\text{-CH}_3) is an electron-donating group. This increases the electron density on the nitrogen of the amine group, enhancing its basicity.

Conclusion: The increasing order of basic strength is:

II < I < III

Hence, the correct answer is: II < I < III.