See image — Aldehydes Ketones and Carboxylic Acids Chemistry Question

💡 Solution & Explanation

Step 1 - Identify the starting material: The structure shown is glutaric acid (pentanedioic acid), HOOC-CH2-CH2-CH2-COOH (a 1,5-diacid with a CH2 branch making it a five-carbon diacid). Step 2 - Reaction with BaCO3 under heat (A): Heating a dicarboxylic acid with BaCO3 (barium carbonate, a mild base/thermal catalyst) causes pyrolytic decarboxylation and cyclization. For glutaric acid (a 1,5-diacid), this gives cyclopentanone (a five-membered ring ketone) as product A. The reaction proceeds via formation of a barium salt intermediate that undergoes intramolecular ketone formation with loss of CO2 and water. Step 3 - Reaction with NH2—NH2 (hydrazine) to give B: Cyclopentanone reacts with hydrazine (NH2—NH2) to form a hydrazone. The carbonyl group (C=O) undergoes condensation with hydrazine to give cyclopentylidene hydrazone (C=N—NH2), which is product B. Step 4 - Reaction with heat and KOH (Wolff-Kishner reduction conditions) to give C: Heating the hydrazone B with KOH (strong base) under heat constitutes the Wolff-Kishner reduction conditions. This converts the C=N—NH2 group to CH2 with loss of N2, reducing the ketone to the corresponding hydrocarbon. Cyclopentylidene hydrazone is thus converted to cyclopentane (C). Step 5 - Why other options fail: (a) CH3—CH=CH—CH2 is an open-chain compound, not formed from this cyclic pathway. (b) Cyclopentanone is intermediate A, not the final product C. (d) Cyclopentylidene hydrazone is intermediate B, not the final product C. Therefore, the correct answer is C.