Benzaldehyde reacts with alcoholic KCN to give :

Options

A. `C_(6)H_(5)CH(OH)CN`
B. `C_(6)H_(5)CH(OH)COC_(6)H_(5)`
C. `C_(6)H_(5)CH(OH)COOH`
D. `C_(6)H_(5)CH(OH)CH(OH)C_(6)H_(5)`

Explanation

To solve the question regarding the reaction of benzaldehyde with alcoholic KCN, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Reactants**:
- The reactant is benzaldehyde, which has the chemical formula C₆H₅CHO.

2. **Understand the Reagent**:
- Alcoholic KCN is a source of cyanide ions (CN⁻) in an alcoholic medium. This will facilitate a nucleophilic addition reaction.

3. **Recognize the Type of Reaction**:
- The reaction between benzaldehyde and alcoholic KCN is a nucleophilic addition reaction. In this case, the cyanide ion acts as the nucleophile.

4. **Write the Reaction Mechanism**:
- The nucleophile (CN⁻) attacks the electrophilic carbon of the carbonyl group (C=O) in benzaldehyde.
- This results in the formation of a tetrahedral intermediate.

5. **Formation of the Product**:
- The tetrahedral intermediate rearranges, leading to the formation of a product. The reaction can lead to the formation of benzoin through a condensation reaction.
- The product formed is C₆H₅C(OH)(CN)C₆H₅, which can further rearrange or undergo hydrolysis to yield benzoin.

6. **Final Product**:
- The final product of the reaction is benzoin, which has the structure C₆H₅C(OH)C(=O)C₆H₅.

7. **Select the Correct Option**:
- Among the options provided, the one that matches the product formed (C₆H₅C(OH)C(=O)C₆H₅) is the correct answer.

### Conclusion:
- The reaction of benzaldehyde with alcoholic KCN gives benzoin, which is represented by the structure C₆H₅C(OH)C(=O)C₆H₅.