Question

Identify the product 'B' in the following reaction
\(\text{Toluene}\overset{\text{Chromyl chloride}/\text{CS}_2\,}{\rightarrow }A\overset{\text{H}_3\text{O}^+\,}{\rightarrow }B\)

• A. Benzal chloride
• B. Benzaldehyde
• C. Benzyl alcohol
• D. Benzoic acid

Hint:

Chromyl chloride in CS2 oxidises the methyl group to a chromium complex, which hydrolyses to an aldehyde.

Answer 1

The Correct Option is B

Step 1: Recognise the named reaction:
Controlled oxidation of an aryl methyl group to $-\text{CHO}$ with $\text{CrO}_2\text{Cl}_2$ is the Etard reaction.

Step 2: Product:
The intermediate A is the chromium complex and acid hydrolysis releases $\text{C}_6\text{H}_5\text{CHO}$. So B is benzaldehyde (B).

Final Answer:
Benzaldehyde. \[ \boxed{\text{(B)}} \]