See image — GOC and Organic Chemistry Basics Chemistry Question

💡 Solution & Explanation

# Solution: Basicity Order of Aromatic Amines **Key Principle:** Basicity of aniline derivatives depends on electron density at the nitrogen atom. Electron-donating groups (EDG) increase basicity; electron-withdrawing groups (EWG) decrease basicity. ## Analysis of Each Compound: **(I) Benzene with $-C(NH)NH_2$ (guanidine group)** - The $C=N$ bond is electron-withdrawing - Reduces electron density on N - **Low basicity** **(II) p-Phenylenediamine** ($-NH_2$ at para position) - Strong EDG: $-NH_2$ at para position - Increases electron density on the guanidine nitrogen via resonance - **Highest basicity** ✓ **(III) p-Nitroaniline derivative** - Strong EWG: $-NO_2$ at para position - Withdraws electron density through resonance - **Very low basicity** **(IV) p-Chloroaniline derivative** - Weak EWG: $-Cl$ is slightly withdrawing (despite weak resonance donation) - Net electron-withdrawing effect - **Low-moderate basicity** ## Basicity Order: $$\text{(II)} > \text{(I)} > \text{(IV)} > \text{(III)}$$ **Why (A) is correct:** The para-amino group strongly activates the benzene ring and enhances N basicity. The nitro group in (III) is the strongest deactivator, making it least basic. **Answer: (A)**