See image — Amines Chemistry Question

💡 Solution & Explanation

Concept: N-nitroso amines (R2N-N=O) are formed when secondary amines react with nitrous acid (NaNO2/HCl). The nitrogen must have exactly one N-H bond available for nitrosation. Step 1 - Identify the type of each amine: (a) PhCH2NH2 is a primary aliphatic amine. Primary amines react with nitrous acid to form diazonium salts (unstable for aliphatic) or diazo compounds, NOT N-nitroso amines. (b) 4-CH3-C6H4-NH2 (p-toluidine) is a primary aromatic amine. Primary aromatic amines react with nitrous acid to form stable arenediazonium salts, NOT N-nitroso amines. (c) N-phenylpiperidine is a tertiary amine (no N-H bond). Tertiary amines do not undergo nitrosation to give N-nitroso amines; they have no N-H to replace. (d) C6H5-NHCH3 (N-methylaniline) is a secondary amine. It has one N-H bond and one N-C bond on each side. Secondary amines react with nitrous acid to yield N-nitroso amines: C6H5-N(NO)-CH3. Step 2 - Apply the reaction rule: Only secondary amines (one N-H present, two carbon substituents on nitrogen) produce N-nitroso compounds upon treatment with NaNO2/HCl. Step 3 - Elimination of wrong options: - (a) primary amine → diazonium/unstable intermediate, not N-nitroso - (b) primary aromatic amine → arenediazonium salt, not N-nitroso - (c) tertiary amine → no reaction (or salt formation), not N-nitroso - (d) secondary amine → N-nitroso amine ✓ Therefore, the correct answer is D.