Benzaldehyde, when heated with an alcoholic solution of potassium cyanide, forms :

Options

A. Benzyl alcohol
B. Benzoic
C. Hydrobenzamide
D. Benzoic acid

Answer

To solve the problem of what benzaldehyde forms when heated with an alcoholic solution of potassium cyanide, we can follow these steps:

### Step 1: Identify the Reactants
Benzaldehyde (C₆H₅CHO) is the primary reactant in this reaction. It is an aromatic aldehyde.

### Step 2: Understand the Role of Potassium Cyanide (KCN)
Potassium cyanide is a strong nucleophile and can react with carbonyl compounds. In this case, it will react with the carbonyl group (C=O) of benzaldehyde.

### Step 3: Mechanism of Reaction
1. **Nucleophilic Attack**: The cyanide ion (CN⁻) from KCN attacks the carbon atom of the carbonyl group in benzaldehyde. This results in the formation of a tetrahedral intermediate.

2. **Formation of a Negative Charge**: The attack leads to the formation of a negatively charged intermediate where the carbonyl oxygen carries a negative charge.

3. **Rearrangement**: This intermediate can then rearrange, allowing the negative charge to stabilize through the formation of a new bond with another molecule of benzaldehyde.

4. **Formation of Benzoic Acid**: The final product after rearrangement and stabilization is benzoic acid (C₆H₅COOH).

### Step 4: Conclusion
The product formed when benzaldehyde is heated with an alcoholic solution of potassium cyanide is benzoic acid.

### Final Answer
The correct answer is **benzoic acid**.

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