See image — GOC and Organic Chemistry Basics Chemistry Question

💡 Solution & Explanation

# Basicity of Aniline Derivatives **Key Principle:** The basicity of anilines depends on electron density at the nitrogen atom. Electron-donating groups increase basicity; electron-withdrawing groups decrease it. ## Analysis of Each Compound: **Compound I (Aniline):** - Reference compound with moderate basicity - $-NH_2$ has no substituents affecting electron density **Compound IV (4-Methylaniline/p-Toluidine):** - $-CH_3$ is electron-donating (alkyl group) - Increases electron density on $N$ via inductive effect - **Most basic** ✓ **Compound II (4-Nitroaniline):** - $-NO_2$ is strongly electron-withdrawing - Resonance delocalization of lone pair onto benzene ring - Significantly decreases basicity - **Least basic** ✗ **Compound III (4-Aminobenzaldehyde):** - $-CHO$ is electron-withdrawing (carbonyl withdraws through resonance) - Intermediate effect between I and II - More basic than II, less than I ## Basicity Order (Decreasing): $$IV > I > III > II$$ **Answer: (3) $IV > I > III > II$** ✓ This matches the correct option by properly accounting for electron-donating and electron-withdrawing effects on the aniline nitrogen's electron density.