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JEE Advanced levelOne or more correct optionsDifficulty 3 of 3co103

Which of the following combinations give an alpha,beta-unsaturated carbonyl compound by loss of one when warmed with dilute NaOH? (One or more answers)

  1. Aethanal alone, giving
  2. Bbenzaldehyde and excess propanone, giving
  3. Cmethanal and 2,2-dimethylpropanal, giving 2,2-dimethylbut-3-enal
  4. Dbenzaldehyde and benzophenone, giving 1,2,2-triphenylethenyl phenyl ketone

Answer: A, B

Ethanal gives but-2-enal by aldol condensation. Benzaldehyde and propanone give 4-phenylbut-3-en-2-one by Claisen-Schmidt condensation. Methanal and 2,2-dimethylpropanal have no alpha-hydrogens and give Cannizzaro products. Benzophenone has no alpha-hydrogen and cannot form an enolate.
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