Which of the following adds HCN (with trace CN-) most readily?

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JEE Main levelSingle correct optionDifficulty 2 of 3o1122

Which of the following adds $HCN$ (with trace $CN X^{-}$ ) most readily?

A $CH X_{3} - CO - CH X_{3}$
B $C X_{6} H X_{5} - CO - CH X_{3}$
C $C X_{6} H X_{5} - CO - C X_{6} H X_{5}$
D $CH X_{3} - CHO$

Answer: D

An aldehyde has one small substituent and a more electrophilic carbon than a ketone. Alkyl or aryl groups on the carbonyl carbon donate electrons and add steric bulk, so the order is

CH X_{3} CHO

first, then acetone, then the aryl ketones.

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Which of the following adds HCN (with trace CNX−) most readily?

Answer: D

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Which of the following adds $HCN$ (with trace $CN X^{-}$ ) most readily?