# Mechanism of toluene oxidation with CrO3

What is the mechanism for the following oxidation of toluene with $\ce{CrO3}$ in acetic anhydride?

Use of chromic oxide ($\ce{CrO3}$): Toluene or substituted toluene is converted to benzylidene diacetate on treating with chromic oxide in acetic anhydride. The benzylidene diacetate can be hydrloyzed to corresponding benzaldehyde with aqueuous acid.

• This appears to be the Étard reaction, which proceeds via a 2,3 Sigmatropic rearrangment. You can read about it here. – Tim Biegeleisen Sep 3 '16 at 7:00
• In etard reaction Chromylchloride is used and if it were like etard reaction then methyl of toluene will not get disubsituted. – JM97 Sep 3 '16 at 7:04
• I don't see why CrO2Cl2 would behave any differently than chromic oxide. Can you explain why you would expect a different outcome? – Tim Biegeleisen Sep 3 '16 at 7:10
• wikipedia mechanism is based on papers of 1950-60s .. pubs.acs.org/doi/abs/10.1021/ic200877f this is a recent mechanism proposed – vishesh jain Aug 27 '19 at 8:34
• What is the evidence that the Etard reaction is [2,3]-sigmatropic rearrangement? Read this: chemistry.stackexchange.com/questions/140039/… – user55119 Sep 17 '20 at 20:15