See image — Hydrocarbons Chemistry Question

💡 Solution & Explanation

Step 1 - Reaction of cyclohexene with HOCl (halohydrin formation): HOCl adds to cyclohexene via an electrophilic addition mechanism. The electrophilic Cl+ (from HOCl) attacks the double bond to form a chloronium ion (bridged intermediate). Water then attacks the more substituted carbon from the opposite face (anti addition). This gives trans-2-chlorocyclohexanol as product A, because the OH and Cl add in an anti fashion (trans relationship on the ring). Step 2 - Reaction of trans-2-chlorocyclohexanol with NaOH/H2O at 25°C: Under mild basic conditions (NaOH, H2O, 25°C), the alkoxide formed from the trans-chlorohydrin undergoes intramolecular SN2 reaction. The oxygen attacks the carbon bearing the chlorine from the back side (inversion), displacing Cl-. Since the OH and Cl are trans to each other in A, the intramolecular SN2 is geometrically favored and proceeds to give cyclohexene oxide (1,2-epoxycyclohexane) as product B. The oxygen and chlorine are on opposite faces, so the backside attack by the alkoxide oxygen on the C-Cl bond proceeds readily to form the epoxide. Step 3 - Why other options fail: - Options (a) and (d): cis-2-chlorocyclohexanol would form if addition were syn, but halohydrin formation is strictly anti, giving the trans isomer. So A cannot be cis. - Option (b): If A were trans-2-chlorocyclohexanol and B were anti-diol, that would require direct hydrolysis conditions (acidic or specific oxidative conditions), not mild NaOH/H2O at 25°C which favors epoxide formation via intramolecular displacement. - Option (c): A = trans-2-chlorocyclohexanol (correct halohydrin stereochemistry) and B = cyclohexene oxide (correct product of intramolecular SN2 under mild NaOH/H2O). This is consistent with all mechanistic principles. Therefore, the correct answer is C.