Question

Benzyl alcohol is obtained from benzaldehyde by the following reaction.

• A. Aldol condensation
• B. Perkin reaction
• C. Cross aldol condensation
• D. Cannizzaro reaction

Hint:

Benzaldehyde has no \( \alpha \)-hydrogen, so with strong base it disproportionates (Cannizzaro) to benzyl alcohol plus benzoate.

Answer 1

The Correct Option is D

Step 1: Ask which named reaction turns an aldehyde into an alcohol. That points to a reduction, and for an aldehyde lacking \( \alpha \)-hydrogen the built-in reduction pathway is the Cannizzaro reaction.
Step 2: In the Cannizzaro reaction two molecules of the same aldehyde react in strong base: hydride shifts from one carbonyl carbon to the other. The molecule receiving hydride becomes the primary alcohol, and the molecule losing hydride becomes the carboxylate.
Step 3: Applied to benzaldehyde, half of it becomes benzyl alcohol and half becomes benzoate ion, matching the product asked in the question.
Step 4: The other options require an \( \alpha \)-hydrogen (aldol, cross aldol) or produce an unsaturated acid (Perkin), so none of them yields benzyl alcohol. The answer is the Cannizzaro reaction.