How will you prepare benzaldehyde from toluene?

Explanation

To prepare benzaldehyde from toluene, we can follow these steps:

### Step 1: Oxidation of Toluene
- **Reactants**: Toluene (C6H5CH3) and chromium chloride (CrO2Cl2).
- **Conditions**: The reaction should be carried out in a solvent such as carbon disulfide (CS2) or carbon tetrachloride (CCl4).
- **Reaction**: Toluene is oxidized to form a brown chromium complex. The methyl group (–CH3) of toluene is oxidized to a formyl group (–CHO), resulting in the formation of a complex.

### Step 2: Formation of Brown Chromium Complex
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