JEE Chemistry 2023 Question with Solution

Given: The sequence starts from propanal and methanal and finally gives product $B$ with molecular formula $C_5H_8O_3$.

Find: The correct statement about product $B$.

From the solution text, the reaction sequence is interpreted as formation of an aldol-type product first, followed by reaction with $\text{NaCN}$ and then hydrolysis to give a carboxylic acid containing a stereogenic center.

The key conclusions explicitly stated in the solution are:

1. The final product is a racemic mixture.
2. The final product contains a carboxylic acid group.
3. A carboxylic acid reacts with saturated $\text{NaHCO}_3$ solution to release $CO_2$ gas.

Therefore, the correct statement for product $B$ is: it is a racemic mixture and gives a gas with saturated $\text{NaHCO}_3$ solution.

The correct option is C.

Given: Product $B$ is obtained after reaction with $\text{NaCN}$ followed by hydrolysis.

Find: Which property matches the final product.

Reaction with $\text{NaCN}$ generally introduces a nitrile functionality through cyanide addition/substitution. On hydrolysis, the nitrile is converted into a carboxylic acid. Hence the final product is acidic rather than neutral.

Since a new chiral center is formed and no chiral reagent is used, the product is obtained as a racemic mixture rather than as a single optically active form.

An acidic compound containing $-COOH$ reacts with saturated $\text{NaHCO}_3$ to evolve $CO_2$ gas. Hence the statement matching product $B$ is option C.