See image — Amines Chemistry Question

💡 Solution & Explanation

Concept: When primary amines react with HNO2 (nitrous acid), they form unstable diazonium ions which decompose to give carbocations. For cyclopropylmethylamine (cyclopropyl-CH2-NH2), the diazonium ion decomposes to give the cyclopropylmethyl cation, which is a non-classical carbocation that undergoes rapid rearrangement. Step 1: Cyclopropyl-CH2-NH2 reacts with HNO2 to form the cyclopropylmethyl diazonium ion, which loses N2 to give the cyclopropylmethyl carbocation (cyclopropyl-CH2+). Step 2: The cyclopropylmethyl cation is in rapid equilibrium with the cyclobutyl cation and the homoallyl (but-3-en-1-yl) cation through a non-classical carbocation rearrangement (ring opening/closure). This is the well-known cyclopropylmethyl-cyclobutyl-homoallyl cation equilibrium. Step 3: These carbocations capture water (solvolysis) to give the corresponding alcohols: - Cyclobutyl cation + H2O → cyclobutanol (47%) - Homoallyl cation + H2O → CH2=CH-CH2-CH2-OH (but-3-en-1-ol) - Cyclopropylmethyl cation + H2O → cyclopropyl-CH2-OH (cyclopropylmethanol) (48%) Step 4: Product A at 48% yield corresponds to cyclopropylmethanol, which is a cyclopropane ring bearing a CH2OH group — matching option (b). Why other options fail: - Option (a): CH2=CH-CH(OH)-CH3 would require a different rearrangement pathway not consistent with this cation system. - Option (c): Methylenecyclopropane would be an alkene product, not expected from solvolysis. - Option (d): Cyclopropene is a strained ring product not formed in this reaction. Therefore, the correct answer is B.