Strong oxidizing agents oxidize toluene and its derivatives to benzoic acids. However, it is possible to stop the oxidation at the aldehyde stage with suitable reagents that convert the methyl group to an intermediate that is difficult to oxidize further. The following methods are used for this purpose.

Toluene reacts with two moles of chromyl chloride in carbon tetrachloride solution followed by decomposition in water. What is the name of this reaction?

Etard reaction 

Etard Reraction: It consists in treating toluene with chromyl chloride in carbon tetrachloride solution. The precipitated complex is then decomposed with water.