- Potassium permanganate (\(\mathrm{KMnO_4}\)) in alkaline medium is used to oxidize alkyl groups on aromatic rings to carboxylic acids, forming compounds like benzoic acid.
Step 1: Analyze the reaction components.
The given reaction involves a methyl group (\(-\mathrm{CH_2CH_3}\)) attached to a benzene ring. The reagents used are:
\(\mathrm{KMnO_4 / KOH}\): Potassium permanganate in alkaline medium, which is a strong oxidizing agent.
\(\mathrm{H_3O^+}\): The acidic medium used to neutralize the alkaline environment after the oxidation reaction.
Step 2: Understand the oxidation reaction.
Potassium permanganate (\(\mathrm{KMnO_4}\)) is a powerful oxidizer and will oxidize the methyl group attached to the benzene ring:
The methyl group (\(-\mathrm{CH_2CH_3}\)) will be converted into a carboxyl group (\(-\mathrm{COOH}\)), which is a typical transformation when an alkyl side chain is oxidized using potassium permanganate.
In alkaline medium, the methyl group undergoes a further oxidation process, and the final product is a carboxylic acid attached to the benzene ring.
Step 3: Neutralization and product formation.
After the oxidation, the reaction mixture is treated with \(\mathrm{H_3O^+}\), which neutralizes the alkaline medium, and the product is benzoic acid (\(\mathrm{C_6H_5COOH}\)).
Step 4: Identify the correct structure.
The correct structure after oxidation is benzoic acid, which is represented by Option (2).
Thus, the correct answer is Option (2), which shows the structure of benzoic acid.
