Question

Identify the compound formed by action of chromyl chloride on toluene in presence of \(\text{CS}_2\) and hydrolysed further?

• A. Chlorobenzene
• B. Benzal chloride
• C. Benzaldehyde
• D. Benzoic acid

Hint:

Etard reaction is a selective oxidation that stops at aldehyde stage, unlike strong oxidizing agents which form benzoic acid.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
The reaction described is a specific name reaction known as the Étard reaction. It involves the partial oxidation of an alkylbenzene (like toluene) using chromyl chloride (\(\text{CrO}_2\text{Cl}_2\)).
Step 2: Key Formula or Approach:
Identify the reagents and the substrate to recall the specific organic name reaction and its final product after hydrolysis.
Step 3: Detailed Explanation:
In the Étard reaction, toluene reacts with chromyl chloride in a non-polar solvent like carbon disulfide (\(\text{CS}_2\)) or carbon tetrachloride (\(\text{CCl}_4\)).
The reaction proceeds via the formation of a brown chromium complex: \[ \text{C}_6\text{H}_5\text{CH}_3 + 2\text{CrO}_2\text{Cl}_2 \xrightarrow{\text{CS}_2} \text{C}_6\text{H}_5\text{CH}(\text{OCrOHCl}_2)_2 \text{ (brown complex)} \] This intermediate complex is then subjected to acid hydrolysis to yield an aldehyde: \[ \text{C}_6\text{H}_5\text{CH}(\text{OCrOHCl}_2)_2 \xrightarrow{\text{H}_3\text{O}^+} \text{C}_6\text{H}_5\text{CHO} + \text{Cr-byproducts} \] The final organic product formed is \(\text{C}_6\text{H}_5\text{CHO}\), which is Benzaldehyde.
Step 4: Final Answer:
The product is benzaldehyde, corresponding to option (C).