JEE Main Chemistry question

Claisen condensation is not given by

(A)Diphenyl carbonate (an aryl-aryl carbonate ester)
(B)An aliphatic ester with α-hydrogens
(C)An aryl ester with an α-CH₂ on the acyl side
(D)A propanoate-type ester with α-hydrogensCorrect

Answer: (D)

Solution

Claisen condensation requires an ester bearing at least one α-hydrogen on the acyl (carbonyl-side) carbon chain, so that base can generate the enolate which then attacks the carbonyl carbon of a second ester molecule. An ester whose acyl portion has no α-hydrogen (e.g. an aryl carbonate/ester with no CH adjacent to

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Question ID VK-149166