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Which product is obtained when benzophenone (C₆H₅COC₆H₅) is reduced with NaBH₄ in ethanol?

medium MCQ 3 marks Class 12 · Chemistry · Aldehydes Ketones and Carboxylic Acids
  1. 4-phenyl-1,2-diphenylethanol
  2. 1,2-diphenylethanol
  3. 1,2-diphenylethane
  4. 4-phenyl-1-phenylethanol
Answer
1,2-diphenylethanol

The correct answer is 1,2-diphenylethanol — This matches option (b).

Step-by-step solution

  1. Recognise that NaBH₄ reduces ketones to alcohols with addition of a hydride to the carbonyl carbon.
  2. Benzophenone has a single carbonyl group; reduction gives a secondary alcohol.
  3. The new stereogenic centre is at the former carbonyl carbon; both phenyl groups are on the same carbon.
  4. The product is thus 1,2-diphenylethanol (C₆H₅CH(OH)C₆H₅).
  5. This matches option (b).
Common mistake: Thinking the product is a benzyl alcohol or an alkane

Concept tested: reduction of ketone to secondary alcohol

Published · How this solution was prepared and checked

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