Question 58: Complete the following reaction :
[A] on treatment with \mathrm{HCN} gives [B]. On heating [B]
with concentrated \mathrm{H_2SO_4}, [C] is formed.
Answer: Option (2)
Explanation:
Compound [A] is cyclohexanone, which reacts with \mathrm{HCN}
to form a cyanohydrin [B].
In this reaction, the \mathrm{CN^-} ion attacks the carbonyl carbon,
and the oxygen is protonated to give a hydroxyl group.
Thus, compound [B] is a cyanohydrin containing both
\mathrm{-OH} and \mathrm{-CN} groups on the same carbon.
On heating [B] with concentrated \mathrm{H_2SO_4},
the nitrile group undergoes hydrolysis to form a carboxylic acid group.
Therefore, the final product [C] is cyclohexene carboxylic acid.
This corresponds to Option (2).