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JEE Main · 2023 · 11 Apr 2023 · Shift 2 · Aldehydes Ketones and Carboxylic Acids

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The major product formed in the following reaction is:
(see reaction scheme)
(A) (see structure)
(B) (see structure)
(C) (see structure)
(D) (see structure)

Choose the correct answer from the options given below :
Structure A
A
Structure B
B
Structure C
C
Structure D
D
  1. (A)A only
  2. (B)B only✓ Correct
  3. (C)C only
  4. (D)D only

Answer: (B)

Solution

Zinc amalgam with hydrochloric acid (Clemmensen conditions) reduces the aldehyde group to a methyl group, so becomes . The benzylic alcohol then ionises in the hot acidic medium to a stabilised benzylic carbocation, which loses a proton to form a carbon-carbon double bond. Elimination takes the direction that puts the double bond in conjugation with the ring, giving the most stable product . This conjugated alkene is the major product.

JEE Main · 2023 · 11 Apr 2023 · Shift 2 · Single correct option

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