When benzaldehyde (or any other aromatic aldehyde) is heated with anhydride of an aliphatic acid (containing two `alpha` - hydroge atoms) in presence of its sodium salt, condensation takes place to form an unsaturated carboxylic acid. This reaction is called

Options

A. Perkin reaction
B. Claisen - Schmidt reaction
C. Witting reaction
D. Benzoin condensation

Answer

To solve the question regarding the reaction of benzaldehyde (or any aromatic aldehyde) with an anhydride of an aliphatic acid containing two alpha-hydrogen atoms in the presence of its sodium salt, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Reactants**:
- We have benzaldehyde (an aromatic aldehyde).
- We have an anhydride of an aliphatic acid (e.g., acetic anhydride) that contains at least two alpha-hydrogen atoms.
- We also need the sodium salt of the corresponding acid (e.g., sodium acetate).

2. **Understand the Reaction Type**:
- The reaction involves condensation, which means that two molecules combine to form a larger molecule with the elimination of a small molecule (often water or an alcohol).

3. **Reaction Mechanism**:
- The acetate ion (from the sodium salt of the acid) acts as a nucleophile and attacks the carbonyl carbon of the anhydride.
- This leads to the formation of an intermediate compound.
- The intermediate undergoes further transformations, resulting in the formation of an alpha, beta-unsaturated carboxylic acid.

4. **Final Product**:
- The final product of this reaction is an alpha, beta-unsaturated carboxylic acid.

5. **Name the Reaction**:
- This specific reaction is known as the **Perkin Reaction**. It is characterized by the formation of unsaturated acids from aromatic aldehydes and anhydrides of aliphatic acids.

### Conclusion:
The reaction described in the question is called the **Perkin Reaction**.