In Etard's reaction toluene is oxidised to benzaldehyde using

Options

A. `H_(2)O_(2)`
B. `Cl_(2)`
C. Chromium trioxide or `CrO_(2)Cl_(2)`
D. `"KMnO"_(4)`

Explanation

To solve the question regarding the reagent used in Etard's reaction to oxidize toluene to benzaldehyde, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Reaction**:
- The reaction in question is the Etard reaction, where toluene (C7H8) is oxidized to benzaldehyde (C7H6O).

2. **Write the Chemical Equation**:
- The chemical equation for the reaction can be represented as:
\[ \text{C}_6\text{H}_5\text{CH}_3 \xrightarrow{\text{Reagent}} \text{C}_6\text{H}_5\text{CHO} \]
- Here, C6H5CH3 is toluene and C6H5CHO is benzaldehyde.

3. **Determine the Oxidizing Agent**:
- In the Etard reaction, the oxidation of the methyl group in toluene occurs. This requires a strong oxidizing agent.

4. **Identify the Correct Reagent**:
- The reagent used in the Etard reaction is **chromyl chloride (CrO2Cl2)** or **chromium trioxide (CrO3)**. Both are effective oxidizing agents for this reaction.

5. **Conclusion**:
- Therefore, the reagent used in the Etard reaction to oxidize toluene to benzaldehyde is chromyl chloride (CrO2Cl2) or chromium trioxide (CrO3).

### Final Answer:
In Etard's reaction, toluene is oxidized to benzaldehyde using **chromyl chloride (CrO2Cl2)** or **chromium trioxide (CrO3)**.

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