In the reaction sequence `C_6H_5CHOoverset(NaCN//HCl)rarr(X)overset(H_2"O"//H^o+)rarr` product, Product will be

Options

A. Optically inactive acid
B. Optically inactive `alpha` - hydroxy acid
C. Racemic mixture of two optically active `alpha` - hydroxy acid
D. Recemic mixture of two optically active secondary alcohols

Answer

To solve the question regarding the reaction sequence of benzaldehyde (C₆H₅CHO) with NaCN and HCl, followed by hydrolysis, we will break it down step by step.

### Step 1: Reaction of Benzaldehyde with NaCN
1. **Identify the Reactants**: The starting material is benzaldehyde (C₆H₅CHO).
2. **Nucleophilic Attack**: When benzaldehyde reacts with sodium cyanide (NaCN), the cyanide ion (CN⁻) acts as a nucleophile and attacks the carbonyl carbon of the aldehyde group (C=O).
3. **Formation of Cyanohydrin**: This results in the formation of a cyanohydrin. The reaction can be represented as:
\[ C_6H_5CHO + NaCN \rightarrow C_6H_5C(OH)(CN) \]
This compound is known as benzoin cyanohydrin (X).

### Step 2: Hydrolysis of the Cyanohydrin
1. **Hydrolysis Reaction**: The next step involves the hydrolysis of the cyanohydrin (C₆H₅C(OH)(CN)) in the presence of water (H₂O) and an acid (H⁺).
2. **Conversion to Carboxylic Acid**: During hydrolysis, the cyanide group (CN) is converted into a carboxylic acid (COOH). The reaction can be represented as:
\[ C_6H_5C(OH)(CN) + H_2O \xrightarrow{H^+} C_6H_5C(OH)(COOH) \]
The final product is benzoin carboxylic acid.

### Step 3: Determine the Optical Activity
1. **Chirality**: The carbon atom that is bonded to the hydroxyl group (OH) and the carboxylic acid (COOH) becomes a chiral center because it is attached to four different groups (C₆H₅, OH, COOH, and H).
2. **Racemic Mixture**: Since this carbon is chiral, the product will exist as a racemic mixture, containing both enantiomers (R and S configurations).

### Final Product
The final product after the complete reaction sequence is benzoin carboxylic acid, which is a secondary alcohol that forms a racemic mixture due to the presence of a chiral center.

### Summary of the Steps
1. Benzaldehyde reacts with NaCN to form benzoin cyanohydrin (X).
2. Benzoin cyanohydrin undergoes hydrolysis to form benzoin carboxylic acid.
3. The product is optically active due to the chiral center, resulting in a racemic mixture.