Question

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

• A. Chromium chloride
• B. Chromyl chloride
• C. Chromium oxide
• D. Chromic acid

Hint:

The formation of the brown chromium complex intermediate is what prevents the Etard reaction from continuing the oxidation process all the way to a carboxylic acid, making it highly valuable for synthesizing aldehydes.

Answer 1

The Correct Option is B

Step 1: Understanding the Question:
This is a direct fact-based question testing the knowledge of named organic chemistry reactions, specifically the Etard reaction.

Step 2: Detailed Explanation:
The Etard reaction is a specific chemical reaction used for the partial oxidation of an alkylbenzene (most commonly toluene) to yield an aldehyde (benzaldehyde).
The specific reagent required to perform this controlled oxidation is Chromyl chloride ($CrO_2Cl_2$).
Chromyl chloride reacts with toluene to form a brown chromium complex precipitate. Subsequent hydrolysis of this stable intermediate complex safely produces benzaldehyde without over-oxidizing it into benzoic acid.
Chromic acid ($H_2CrO_4$) is a much stronger oxidizing agent that would push the reaction entirely to the carboxylic acid stage.

Step 3: Final Answer:
The specific reagent is chromyl chloride, matching option (b).