See image — GOC and Organic Chemistry Basics Chemistry Question

💡 Solution & Explanation

## Basic Strength Order Analysis **Basicity depends on electron density at the nitrogen atom.** Factors affecting basicity: - Direct attachment to electron-donating groups → increases basicity - Conjugation with carbonyl groups → decreases basicity - Amide nitrogen (N bonded to C=O) → much weaker base **Analyzing each compound:** **Compound I:** $Ph-NH-CO-CH_3$ (Amide) - N is part of amide group: $N$ is conjugated with $C=O$ - Lone pair delocalizes into carbonyl → very weak base **Compound II:** $Ph-CO-NH-CH_3$ (Amide) - N is amide nitrogen, conjugated with aromatic carbonyl - Basicity reduced due to resonance: $N$ lone pair $\leftrightarrow C=O$ - Weaker than aliphatic amines but stronger than compound I (methyl substitution reduces electron withdrawal) **Compound III:** $Ph-CO-CH_2-NH_2$ (Primary aliphatic amine) - N is not directly conjugated with carbonyl - Isolated $-NH_2$ group with full lone pair density - Strong base (aliphatic amine) **Compound IV:** $Ph(NH_2)-CO-CH_3$ (Aniline derivative with amide) - $NH_2$ is directly attached to benzene ring - Lone pair partially delocalized into aromatic ring - Weaker than compound III (aromatic amine) **Basicity Order:** $$III > IV > II > I$$ Compound III has the strongest basicity (primary aliphatic amine with no conjugation), followed by IV (aromatic amine), then amides II and I. **Answer: (C)**