See image — Aldehydes Ketones and Carboxylic Acids Chemistry Question

💡 Solution & Explanation

Concept: Acid-catalyzed hydrolysis of ester groups followed by decarboxylation, and hydrolysis of an enol ether or tautomerization of an exocyclic alkene (=CH2) under acidic aqueous conditions with heat. Step 1 - Identify the starting material: The starting material is a cyclohexane ring bearing (1) an exocyclic methylene (=CH2) at one carbon, (2) a CO2Et ester at an adjacent carbon, (3) a ketone (C=O) at another ring carbon, and (4) a second EtO2C ester at another ring carbon. Step 2 - Hydrolysis under H3O+/Delta: Under aqueous acid and heat, both ethyl ester groups (CO2Et and EtO2C) are hydrolyzed to carboxylic acids (-COOH). Step 3 - Decarboxylation: Both resulting carboxylic acid groups are beta-keto acids (one is beta to the ring ketone, the other is beta to the enol/ketone system from the exocyclic methylene). Beta-keto acids readily undergo decarboxylation upon heating, losing CO2. The exocyclic methylene (=CH2) under acidic aqueous conditions also tautomerizes; the =CH2 adjacent to the newly formed carboxylic acid (which is beta-keto) decarboxylates to give a methyl group or simply a CH2 that becomes part of the ring ketone system. Step 4 - Net result: After double hydrolysis and double decarboxylation, both ester-bearing carbons lose their -COOH groups as CO2. The exocyclic =CH2 becomes a simple -CH2- (ring carbon), and the two carbonyls remain. The net product is cyclohexane-1,4-dione (unsubstituted), where both ester carbons have been removed as CO2 and the ring retains only the two ketone functionalities. Step 5 - Why other options fail: - Option (a): Retains one CO2Et group, but heat with H3O+ causes full decarboxylation of beta-keto acids, so no ester should remain. - Option (c): A phenol/enol product would require aromatization, which is not consistent with simple hydrolysis/decarboxylation of this substrate. - Option (d): Eliminated because option (b) is correct. Therefore, the correct answer is B.