Question

Select the strongest base from the given compounds:

• A. \(p- NO_2- C_6H_4NH_2\)
• B. \(C_6H_5CH_2- NH_2\)
• C. \(m- NO_2- C_6H_4NH_2\)
• D. \(C_6H_5NH_2\)

Hint:

To determine the basicity of an amine, consider the nature of the substituents on the aromatic ring. Electron-donating groups increase the basicity, while electron-withdrawing groups decrease the basicity.

Answer 1

The Correct Option is C

The basicity of an amine group (-NH\(_2\)) is influenced by the substituents on the aromatic ring. The electron-withdrawing groups (such as -NO\(_2\)) decrease the electron density on the nitrogen, thus reducing the basicity. On the other hand, electron-donating groups (such as -CH\(_2\)) increase the electron density on the nitrogen, enhancing the basicity. - In option [A] (p-NO\(_2\)-C\(_6\)H\(_4\)NH\(_2\)), the -NO\(_2\) group is an electron-withdrawing group and thus decreases the basicity of the amine. - In option [B] (C\(_6\)H\(_5\)-CH\(_2\)-NH\(_2\)), the -CH\(_2\) group is an electron-donating group and increases the basicity of the amine. - In option [C] (m-NO\(_2\)-C\(_6\)H\(_4\)NH\(_2\)), the -NO\(_2\) group is in the meta position, so it has a lesser effect on the electron density of the amine than when it is in the para position. Thus, the base is stronger than in option [A]. - In option [D] (C\(_6\)H\(_5\)NH\(_2\)), the amine is attached to a phenyl group, which neither donates nor withdraws electron density significantly, making it weaker than the amine in option [B]. Thus, the strongest base is m-NO\(_2\)-C\(_6\)H\(_4\)NH\(_2\), which is option [C].