Question

A carbonyl compound reacts with hydrogen cyanide to form cyanohydrin which on hydrolysis forms a recemic mixrture of `alpha`-hydroxy acid. The carbonyl compound `D`.
A. Formaldehyde
B. acetaldehyde
C. acetone
D. diethyl ketone.

Answer 1

Correct Answer - B
Acetaldehyde cyanohydrin `(CH_(3)CH(OH)CN)` and lactic acid `(CH_(3)"CHOH COOH")` which it gives on hydrolyses contain a chiral carbon and hence exist as a racemic mixture. All the other compounds are symmetrical and hence their cyanohydrins and the corresponding `alpha`-hydroxy acids are not optically active because they do contain a chiral carbon.