See image — Alcohols Phenols and Ethers Chemistry Question

💡 Solution & Explanation

Concept: Hydrolysis and decarboxylation of beta-keto esters. Step 1 - Identify the substrate: The starting material is ethyl 2-oxocyclohexane-1-carboxylate, which is a beta-keto ester. The ester group (CO2Et) is at C1 and the ketone carbonyl is at C2 (the beta position relative to the ester). Step 2 - Acid hydrolysis (H3O+): Treatment with aqueous acid hydrolyzes the ethyl ester to give the corresponding carboxylic acid: 2-oxocyclohexane-1-carboxylic acid. This is a beta-keto acid, where the carboxylic acid is beta to the ketone carbonyl. Step 3 - Decarboxylation upon heating (Delta): Beta-keto acids readily undergo decarboxylation upon heating via a six-membered cyclic transition state (enol intermediate), losing CO2. The carboxylic acid group at C1 is lost as CO2, leaving a carbanion/enol at C1 that tautomerizes to give cyclohexanone. Step 4 - Product: The product is simply cyclohexanone, an unsubstituted cyclohexanone ring. This corresponds to option (b). Why other options fail: - (a) 2-formylcyclohexanone: Would require reduction of the ester to an aldehyde, not what H3O+/Delta does. - (c) 2-methylcyclohexanone: Would require the ester to become a methyl group, which does not occur under these conditions. - (d) Cyclohexane-1,2-dione: Would require oxidation or a different reaction pathway; decarboxylation removes the C1 carbon as CO2, not retains it as a ketone. Therefore, the correct answer is B.