Etard reaction in the following is :

Toluene is transformed into benzaldehyde by chromyl chloride. The Etard reaction is the name of this process. Carbon disulfide is employed as the solvent. The methyl group is changed into a chromium complex by chromium chloride. The equivalent aldehyde is produced by this compound on acid hydrolysis.
${\mathrm{C}}_6{\mathrm{H}}_5{\mathrm{CH}}_3\stackrel{{\mathrm{CrO}}_2{\mathrm{Cl}}_2}{⟶}{\mathrm{C}}_6{\mathrm{H}}_5\mathrm{CH}{\left({\mathrm{OCrOHCl}}_2\right)}_2\stackrel{{\mathrm{H}}_2\mathrm{O}}{⟶}{\mathrm{C}}_6{\mathrm{H}}_5\mathrm{CHO}$