Question

The oxidation of toluene to benzaldehyde by chromyl chloride is called

• A. Etard reaction
• B. Riemer-Tiemann reaction
• C. Wurtz reaction
• D. Cannizzaro’s reaction

Hint:

The oxidation of toluene \(\left( C _{6} H _{5} CH _{3}\right.\) with chromyl chloride \(\left( CRO _{2} Cl _{2}\right)\) in \(CCl _{4}\) or \(CS _{2}\) to give benzaldehyde is called the Etard reaction.

Answer 1

The Correct Option is A

The given question asks about the specific reaction involved in the oxidation of toluene to benzaldehyde using chromyl chloride. The correct answer here is the Etard reaction.

1. Understanding the Process: The Etard reaction is a chemical reaction which involves the oxidation of an alkyl group on an aromatic ring to a formyl group. In this specific case, toluene (methylbenzene) is oxidized to benzaldehyde.

2. Reagent and Mechanism: Chromyl chloride (CrO₂Cl₂) is used to oxidize toluene. The reaction proceeds through the formation of a complex with the alkyl group, which is then hydrolyzed to yield the aldehyde.

3. Why Other Options are Incorrect:

   • Riemer-Tiemann reaction: This reaction involves the formation of ortho-hydroxybenzaldehyde from phenol with chloroform and a base. It is not used for oxidizing toluene to benzaldehyde.
   • Wurtz reaction: This reaction is a coupling reaction involving alkyl halides and sodium metal to form higher alkanes. It is not related to oxidation processes.
   • Cannizzaro’s reaction: This is a redox reaction involving aldehydes that do not have alpha hydrogen, leading to the formation of alcohol and carboxylic acid. It is not involved in the transformation of toluene to benzaldehyde.

4. Conclusion: Since the oxidation of toluene to benzaldehyde using chromyl chloride specifically fits the description of the Etard reaction, it is the correct answer.