Which reducing agent reduces ethyl benzoate to benzyl alcohol?

• A. NaBH4
• B. LiAlH4
• C. H2/Pd
• D. PCC

Answer: (B)

The reaction requires breaking the ester C–O bond and delivering hydride to the carbonyl carbon, all the way to the primary alcohol. A very strong hydride donor like lithium aluminum hydride can do this: it donates hydride to the carbonyl carbon of the ester, kicking out the alkoxide, forming an aldehyde intermediate first, and then delivering another hydride to give the primary alcohol. After work-up, you get benzyl alcohol.

NaBH4 is milder and typically reduces aldehydes and ketones, not esters under normal conditions, so it can’t efficiently reduce ethyl benzoate to benzyl alcohol. H2/Pd can hydrogenate some substrates but esters usually resist under standard conditions and won’t reliably convert to the alcohol. PCC is an oxidizing agent, not a reducing one, so it wouldn’t produce the alcohol from the ester.