What is the main reactant in the prepartion of benzaldehyde by Etard's reaction?

Options

A. Toluene
B. Ethyl benzene
C. Benzoyl chloride
D. Sodium benzoate

Answer

To solve the question regarding the main reactant in the preparation of benzaldehyde by Etard's reaction, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Etard's Reaction**:
- Etard's reaction is a method used to convert toluene into benzaldehyde. This involves the oxidation of the methyl group (-CH3) of toluene to an aldehyde group (-CHO).

2. **Identifying the Reactants**:
- The primary reactant in this reaction is toluene (C6H5CH3). Toluene is an aromatic hydrocarbon that contains a methyl group attached to a benzene ring.

3. **Oxidizing Agent**:
- The oxidizing agent used in this reaction is chromic oxychloride (CrO2Cl2). This reagent facilitates the oxidation of the methyl group to form the aldehyde.

4. **Reaction Overview**:
- The reaction can be summarized as follows:
\[ \text{C}_6\text{H}_5\text{CH}_3 + \text{CrO}_2\text{Cl}_2 \rightarrow \text{C}_6\text{H}_5\text{CHO} + \text{by-products} \]
- In this reaction, toluene is oxidized to benzaldehyde.

5. **Conclusion**:
- Therefore, the main reactant in the preparation of benzaldehyde by Etard's reaction is **toluene**.

### Final Answer:
The main reactant in the preparation of benzaldehyde by Etard's reaction is **toluene**.