Question

Write the reaction involved in Etard reaction.

Hint:

Aldehydes are generally more reactive than ketones towards nucleophilic addition. Clemmensen reduction converts carbonyl group into \(-CH_2-\) group.

Answer 1

Step 1: Etard reaction definition.
The Etard reaction converts an aromatic $-CH_3$ group directly to $-CHO$ using chromyl chloride ($CrO_2Cl_2$) in $CS_2$, followed by hydrolysis.
Step 2: Reaction.
\[C_6H_5CH_3 + 2CrO_2Cl_2 \xrightarrow{CS_2} C_6H_5CH(OCrOCl_2)_2 \xrightarrow{H_2O} C_6H_5CHO\] A brown chromyl chloride complex is first formed, then hydrolysed to benzaldehyde.
Step 3: Product.
\[ \boxed{C_6H_5CH_3 \xrightarrow{CrO_2Cl_2,\;H_2O} C_6H_5CHO\text{ (Benzaldehyde)}} \]