NEETChemistryAldehydes and Ketones
Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): The major product obtained from the cross-aldol condensation of cyclohexanone and benzaldehyde, followed by heating with dilute NaOH, is 2-benzylcyclohex-2-en-1-one. Reason (R): Base-catalyzed dehydration of the intermediate aldol addition product requires the removal of an acidic -hydrogen to form
Options
- ABoth (A) and (R) are true and (R) is the correct explanation of (A)
- BBoth (A) and (R) are true but (R) is not the correct explanation of (A)
- C(A) is true but (R) is false
- D(A) is false but (R) is true
Correct answer
D. (A) is false but (R) is true
Step-by-step solution
The Assertion is false. The cross-aldol condensation between cyclohexanone and benzaldehyde yields 2-benzylidenecyclohexan-1-one as the major product, which features an exocyclic double bond. The product mentioned in the assertion, 2-benzylcyclohex-2-en-1-one, has an endocyclic double bond that is , to the carbonyl group. The Reason is true. Under basic conditions, dehydration proceeds via the E1cB mechanism, which necessitates the abstraction of an acidic proton to the carbonyl group. In the aldol addition interme