Which of the following is used as reagent in Etard reaction?

Step-by-step solution

In the Étard reaction, an aromatic or heterocyclic methyl group undergoes direct oxidation to an aldehyde using chromyl chloride ( CrO₂ Cl₂ ), proceeding through an intermediate chromyl ester that is hydrolyzed to yield the aldehyde product. For instance, toluene is converted to benzaldehyde: C₆ H₅-CH₃ CrO₂ Cl₂, CS₂ [C₆ H₅-CH(OCrOHCl₂)2] H₃ O^+ C₆ H₅-CHO Chromyl chloride ( CrO₂ Cl₂ ) is the specific reagent employed. Among the options, CrCl₃ is incorrect; CrO₃ and H2CrO4 are oxidizing agents but typically lead to o