See image — Amines Chemistry Question

💡 Solution & Explanation

Concept: When a primary aliphatic amine reacts with nitrous acid (HNO2, generated in situ from NaNO2/HCl), it forms a highly unstable aliphatic diazonium salt (R-N2+). Unlike aromatic diazonium salts, aliphatic diazonium salts decompose immediately and spontaneously with loss of N2 gas to generate a carbocation (secondary carbocation in this case, since cyclohexylamine gives a secondary carbocation at C1 of cyclohexane). Step 1: Cyclohexylamine + HNO2 → cyclohexyl diazonium ion (C6H11-N2+) + H2O. This diazonium salt is extremely unstable. Step 2: The diazonium ion rapidly loses N2 to form a secondary carbocation at C1 of cyclohexane. Step 3: The carbocation is captured by the most abundant nucleophile present in the aqueous acidic reaction medium, which is water (H2O). Water attacks the carbocation, followed by deprotonation, to give cyclohexanol. Why other options fail: - (b) Bicyclohexyl would require a coupling reaction between two carbocations or radicals; this is a minor pathway and not the major product. - (c) N-nitrocyclohexylamine (nitrosamide/nitramine) is not formed; HNO2 with primary aliphatic amines gives diazonium ions, not N-nitroso or N-nitro products under standard conditions. N-nitro products require different reagents. - (d) Cyclohexyl nitrite (O-NO) could form as a very minor product, but the major product in aqueous conditions is the alcohol, not the nitrite ester. The major product of the reaction of cyclohexylamine with HNO2 in aqueous conditions is cyclohexanol, because the carbocation intermediate is trapped by water as the dominant nucleophile. Therefore, the correct answer is A.