Question

Examine the structural formulas of following compounds and find out how many compounds can show Claisen condensation reaction.
A.
B.
C.
D.
E.
F

Answer 1

Hint: Only those compounds undergo the Claisen condensation reaction which has α-hydrogen in its structure . Check for each compound in the given options those compounds which have an alpha hydrogen will undergo this reaction and then count how many are there.

Complete step by step solution:In the presence of a strong base, the Claisen condensation reaction forms carbon-carbon bonds between two esters or between one ester and another carbonyl molecule, producing \beta -keto ester or \beta -diketone. Now the compounds which can undergo this reaction must have at least one α-hydrogen , these are those hydrogen atoms which are connected to an α-carbon . α-carbons are those carbon atoms which are directly adjacent to the functional group attached in the compound. In this condensation reaction, in the first step the α-hydrogen is removed by a strong base , resulting in the formation of an enolate anion. The enolate anion then nucleophilically attacks the carbonyl carbon of the other ester. After that, the alkoxy group is removed, and the newly created double alpha-hydrogen is removed by the alkoxide to create a new compound. , highly resonance stabilized enolate anion.
Thus , here among the given compounds in the question , the compounds which have the α-hydrogen are B,D,F.

And so the correct answer will be B,D,F -3 compounds.

Note: The fast condensation reaction will be in the presence of α-hydrogen to the carbonyl group. The hydrogen atom next to the α-hydrogen should not be mistaken as α-hydrogen in answering the question.