Here’s a explanation of how aromatic compounds undergo oxidation:
What Oxidation Is
- Oxidation of aromatic compounds usually involves replacing certain groups attached to the benzene ring with a carboxylic acid group (–COOH).
- The benzene ring itself is very stable and usually does not get oxidized. Instead, the substituents on the ring are oxidized.
Key Points
- Alkyl side chains (like –CH₃, –CH₂CH₃) on the benzene ring can be oxidized to benzoic acid using strong oxidizing agents.
- The aromatic ring remains intact; only the side chain is converted.
- Common oxidizing agents include substances like potassium permanganate (KMnO₄) or chromic acid.
How It Happens
- The oxidizing agent attacks the hydrogen atoms of the side chain attached to the aromatic ring.
- Through a series of electron transfers and bond rearrangements, the side chain is converted into a carboxylic acid group.
- The aromaticity of the benzene ring is preserved throughout the reaction.
Examples
- Toluene (methylbenzene) can be oxidized to benzoic acid.
- Ethylbenzene can also be oxidized to benzoic acid.
Summary
- Benzene rings are resistant to oxidation, but alkyl groups on the ring can be oxidized.
- Strong oxidizing agents are needed.
- The product is usually an aromatic carboxylic acid.