Mechanism of Etard Reaction

The mechanism of the Etard Reaction involves the formation of a complex between the aromatic compound and chromyl chloride. Here’s a simplified explanation:

1. The aromatic methyl group reacts with chromyl chloride to form a complex.
2. This complex undergoes hydrolysis to yield the corresponding aldehyde.
3. For instance, toluene reacts with CrO₂Cl₂ to form a complex, which upon hydrolysis produces benzaldehyde and releases chromium oxide (Cr₂O₃) as a byproduct.

This reaction is specific to aromatic methyl groups and is an important method for synthesizing aromatic aldehydes.