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When benzaldehyde (C₆H₅CHO) is treated with sodium borohydride (NaBH₄) in ethanol at room temperature, which product is formed?

hard MCQ 3 marks Class 12 · Chemistry · Aldehydes Ketones and Carboxylic Acids
  1. Benzyl alcohol
  2. Benzoic acid
  3. Phenylacetaldehyde
  4. Diphenylmethane
Answer
Benzyl alcohol

The correct answer is Benzyl alcohol — Thus the product is C₆H₅CH₂OH, which is named benzyl alcohol.

Step-by-step solution

  1. Identify the functional group in benzaldehyde; it is an aldehyde (‑CHO).
  2. Sodium borohydride is a selective reducing agent that reduces aldehydes to primary alcohols without affecting aromatic rings.
  3. The carbonyl carbon of the aldehyde receives a hydride from NaBH₄, converting the –CHO group to –CH₂OH.
  4. Thus the product is C₆H₅CH₂OH, which is named benzyl alcohol.
Common mistake: Assuming NaBH₄ reduces the aldehyde further to a carboxylic acid.

Concept tested: Reduction of aldehydes with NaBH₄

Published · How this solution was prepared and checked

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