See image — Aldehydes Ketones and Carboxylic Acids Chemistry Question

💡 Solution & Explanation

Step 1 - Identify the transformation: The starting material is a ketone (methyl ketone: CH3-C(=O)-CH2CH2-) with a terminal epoxide on the chain. The product is the fully reduced methylene (CH3-(CH2)3-) chain with the same terminal epoxide intact. In other words, the carbonyl group (C=O) must be reduced to CH2 without touching the epoxide ring. Step 2 - Evaluate option (a) Wolff-Kishner reduction: This uses hydrazine and strong base (KOH) under high heat. Strong base and the harsh basic conditions would open the epoxide ring. Therefore, Wolff-Kishner reduction is not suitable — it would destroy the epoxide. Step 3 - Evaluate option (b) Clemmensen reduction: This uses zinc amalgam and concentrated hydrochloric acid. Strongly acidic conditions would also open the epoxide ring (epoxides are readily cleaved by both acid and base). Therefore, Clemmensen reduction is not suitable either. Step 4 - Evaluate option (c) Thioacetal formation followed by Raney Ni desulfurization: The dithiol (HSCH2CH2SH) would form a cyclic thioacetal at the ketone carbon, and subsequent Raney Ni hydrogenolysis removes the sulfur to give CH2. However, Raney Ni with H2 (or its adsorbed hydrogen) would also hydrogenolytically open or reduce the epoxide ring under the reaction conditions. Thus this method also fails to preserve the epoxide. Step 5 - Conclusion: None of the three listed methods can selectively reduce the ketone carbonyl to CH2 while leaving the epoxide ring completely intact. All three methods use conditions (strong acid, strong base, or Raney Ni/H2) that are incompatible with the sensitive epoxide functionality. Therefore, the correct answer is D.