Four-step lab synthesis of ethyl acetate from acetic acid

Steps:

• Convert CH3COOH to CH3COCl using PCl5.
• Reduce CH3COCl to CH3CHO via Rosenmund reduction with H2/Pd/BaSO4.
• Reduce CH3CHO to CH3CH2OH using NaBH4 in water.
• Esterify CH3COOH with CH3CH2OH using H2SO4 catalyst to form CH3CO2CH2CH3.

Why B is correct:

• Acetic acid (CH3COOH) serves as the sole organic source, providing the acetyl group directly and the ethyl group via sequential reduction (acid chloride to aldehyde to alcohol), per standard organic reduction pathways.

Why the others are wrong:

• A: Ethanol (CH3CH2OH) yields the alcohol directly but requires oxidation to CH3COOH for the acyl group, typically in fewer than four steps.
• C: Acetaldehyde (CH3CHO) can form both components via oxidation/reduction but starts with a more reduced carbon chain, not matching the four-step acid-derived sequence.

Final answer: B