JEE Chemistry 2023 Question with Solution

Given: The starting compound undergoes successive reactions to form A, B and C.

Find: The correct sequence of structures for A, B and C.

Step 1: Reaction with $NaHSO_3$ / dilute $HCl$ and $NaCN, H_2O$ gives cyanohydrin formation. The $CN^-$ ion attacks the carbonyl carbon and the oxygen is protonated. Therefore, A is the cyanohydrin product.

Step 2: Reduction with $LiAlH_4$ converts the nitrile group $(-CN)$ into a primary amine $(-CH_2NH_2)$. Therefore, B is the corresponding amino alcohol.

Step 3: Hydrolysis with $HCl/H_2O$ and heat converts the nitrile-derived functionality to a carboxylic acid. Therefore, C is the corresponding hydroxy carboxylic acid.

The solution states that A is 2-hydroxy-2-methylbutanenitrile, B is 1-amino-2-methylbutan-2-ol, and C is 2-hydroxy-2-methylbutanoic acid.

Hence, the structures match option (4). The correct option is C.

Given: A multistep organic conversion with products A, B and C.

Find: Which option gives the correct structures.

Identify the transformations one by one:

1. Carbonyl compound $\rightarrow$ cyanohydrin using $NaCN/H_2O$ in the presence of $NaHSO_3$ and dilute $HCl$.
2. Nitrile $\rightarrow$ amine on reduction with $LiAlH_4$.
3. Further acidic hydrolysis on heating gives the carboxylic acid derivative shown in the final product set.

So the required pattern is:

• A: $\alpha$-hydroxy nitrile
• B: $\alpha$-hydroxy amine
• C: $\alpha$-hydroxy carboxylic acid

Among the given figures, this sequence appears in option (4), which corresponds to label C in the remapped options.