Question

Structure of residue (A) and compound (B) formed respectively is:

• A.
• B.
• C.
• D.

Hint:

When toluene is oxidized with chromium reagents like CrO\(_2\)Cl\(_2\), the methyl group is oxidized to a carboxyl group. Sodium bisulfite is often used to convert aldehydes to carboxylates.

Answer 1

The Correct Option is A

Step 1: The reaction involves the oxidation of toluene with \(\text{CrO}_2\text{Cl}_2\) and \(\text{CS}_2\). \(\text{CrO}_2\text{Cl}_2\) is a strong oxidizing agent, typically oxidizing the methyl group (\(\text{-CH}_3\)) in toluene to a carboxylic acid (\(\text{COOH}\)) group. This results in a formyl group (\(\text{CHO}\)) being left behind in residue (A), as toluene is partially oxidized. 

Step 2: The treatment with water and NaHSO\(_3\) ensures further oxidation of the formyl group (\(\text{CHO}\)) into a carboxyl group (\(\text{COOH}\)). Diluting with HCl gives a sodium salt of the carboxyl group (\(\text{COONa}\)) in compound (B). 

Thus, the structures of residue (A) and compound (B) are as follows: Residue (A) has a formyl group (\(\text{CHO}\)) and compound (B) has a carboxylate group (\(\text{COONa}\)).