Which of the following reagents is used to reduce benzaldehyde to benzyl alcohol?

CONCEPT:

Reduction of Aldehydes to Alcohols

• Aldehydes, like benzaldehyde, can be reduced to primary alcohols (such as benzyl alcohol) using specific reducing agents.
• The choice of reducing agent depends on the reactivity and the type of reduction required.

EXPLANATION:

• NaBH₄ (Sodium borohydride) — NaBH₄ is a mild reducing agent commonly used to reduce aldehydes and ketones to their corresponding alcohols. It selectively reduces benzaldehyde to benzyl alcohol. 
• Zinc dust acts as a reducing agent. Phenol undergoes reduction reaction in presence of zinc dust. Reduction reaction means the addition of electrons or removal of oxygen or addition of hydrogen.
• Zn/Hg with HCl (Clemmensen reduction) — This reagent is used for the reduction of ketones and aldehydes to alkanes, not alcohols.
• Cu/H₂SO₄ — This reagent is not commonly used for the reduction of aldehydes to alcohols and is more involved in oxidation or other types of reactions.

CONCLUSION:

• NaBH₄ is the reagent used to reduce benzaldehyde to benzyl alcohol.