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: Toluene undergoes oxidation by \(\text{CrO}_2\text{Cl}_2\) and \(\text{CS}_2\). \(\text{CrO}_2\text{Cl}_2\), a potent oxidizing agent, typically converts the methyl group (\(\text{-CH}_3\)) of toluene to a carboxylic acid (\(\text{COOH}\)) group. In this reaction, partial oxidation leaves a formyl group (\(\text{CHO}\)) in residue (A).

Step 2: Subsequent treatment with water and NaHSO\(_3\) further oxidizes the formyl group (\(\text{CHO}\)) to a carboxyl group (\(\text{COOH}\)). Acidification with HCl yields the sodium salt of the carboxyl group (\(\text{COONa}\)) in compound (B).

Therefore, residue (A) contains a formyl group (\(\text{CHO}\)), and compound (B) contains a carboxylate group (\(\text{COONa}\)).