Aromatic aldehyde undergoes condensation on heating with an ethanolic solution of KCN. This reaction is called as

Options

A. Perkin reaction
B. Benzoin condensation
C. Claisen condensation
D. Cannizzaro's reaction

Answer

To solve the question regarding the reaction of aromatic aldehyde with an ethanolic solution of KCN, we will go through the steps of the reaction and identify the type of reaction that occurs.

### Step-by-Step Solution:

1. **Identify the Reactants**:
The reaction involves an aromatic aldehyde, such as benzaldehyde (C6H5CHO), and an ethanolic solution of potassium cyanide (KCN).

2. **Understand the Role of KCN**:
In this reaction, KCN dissociates into K⁺ and CN⁻ ions. The cyanide ion (CN⁻) acts as a nucleophile due to its negative charge.

3. **Electrophilic Center**:
The carbonyl carbon (C=O) in the aromatic aldehyde is electrophilic due to the partial positive charge on it, which is caused by the electronegativity of oxygen.

4. **Nucleophilic Attack**:
The nucleophile (CN⁻) attacks the electrophilic carbon of the carbonyl group in the aldehyde. This results in the formation of a tetrahedral intermediate.

5. **Formation of the Intermediate**:
The tetrahedral intermediate has a negatively charged oxygen (O⁻) and a cyanide group attached to the carbon that was originally part of the carbonyl group.

6. **Proton Transfer**:
The negatively charged oxygen abstracts a proton (H⁺) from the solvent or from the aldehyde, leading to the formation of a hydroxyl group (-OH) and stabilizing the intermediate.

7. **Formation of Benzoin**:
The reaction proceeds further, and through a series of steps, the final product formed is benzoin (C6H5CHOH-C(CN)C6H5). This is a condensation reaction where two molecules of benzaldehyde combine.

8. **Name of the Reaction**:
The reaction that occurs when aromatic aldehydes undergo condensation in the presence of KCN is known as **Benzoin Condensation**.

### Final Answer:
The reaction of aromatic aldehyde with an ethanolic solution of KCN is called **Benzoin Condensation**.

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