See image — Aldehydes Ketones and Carboxylic Acids Chemistry Question

💡 Solution & Explanation

Concept: This problem involves sequential hydrolysis and decarboxylation reactions under acidic aqueous conditions with heat. Step 1 - Ketal hydrolysis: The gem-dimethoxy group (MeO, OMe) on C1 of the cyclohexane ring is a ketal (cyclic or acyclic). Under aqueous acid (H3O+), the ketal is hydrolyzed to a ketone. This converts the C1 carbon bearing two OMe groups into a carbonyl (C=O), giving a diethyl malonate-substituted cyclohexanone intermediate: specifically 2,2-bis(ethoxycarbonyl)cyclohexan-1-one. Step 2 - Ester hydrolysis: Under H3O+ with heat, the two ethyl ester groups (EtO2C and CO2Et) at C2 are hydrolyzed to carboxylic acids, giving 2,2-bis(carboxyl)cyclohexan-1-one (a malonic acid derivative on the ring). Step 3 - Double decarboxylation: The gem-diacid (malonic acid type) at C2, being a beta-keto diacid or a malonic acid adjacent to a ketone, undergoes decarboxylation upon heating. A malonic acid (1,1-dicarboxylic acid) readily loses two CO2 molecules upon heating. The first decarboxylation gives 2-(carboxyl)cyclohexan-1-one (a beta-keto acid). The second decarboxylation of this beta-keto acid also proceeds readily under heat (beta-keto acid decarboxylation), yielding cyclohexanone. Why other options fail: - (a) cyclohexane-1,2-dione: There is no pathway to introduce a second ketone at C2; decarboxylation removes the carboxyl groups entirely rather than converting them to a ketone. - (c) 2-(ethoxycarbonyl)cyclohexan-1-one: The ester groups are hydrolyzed under aqueous H3O+ conditions, so the ethyl ester would not remain intact. - (d) 2-(carboxyl)cyclohexan-1-one: This is an intermediate after first decarboxylation, but it is a beta-keto acid and will lose CO2 upon heating to give cyclohexanone. The final product after complete hydrolysis and double decarboxylation is cyclohexanone. Therefore, the correct answer is B.