Claisen Condensation for Beta-Keto Ester Synthesis

Steps:

• Target molecule is 3-oxobutanoic acid (CH₃COCH₂COOH), a beta-keto acid.
• Beta-keto acids form via hydrolysis of beta-keto esters like ethyl acetoacetate (Y).
• Ethyl acetoacetate synthesizes from Claisen condensation of two ethyl acetate molecules (X).
• Thus, X is ethyl acetate (CH₃COOCH₂CH₃).

Why A is correct:

• A depicts ethyl acetate, the self-condensing ester in Claisen reaction yielding the beta-keto ester precursor per the mechanism: enolate attacks carbonyl, eliminating ethoxide.

Why the others are wrong:

• B (acetone): Lacks ester group needed for Claisen; used in haloform reaction instead.
• C (acetic acid): Cannot undergo Claisen without ester activation.
• D (ethyl malonate): Yields malonic ester derivatives, not acetoacetic acid analogs.

Final answer: A