Below are a few of the simplest ring subtitutions
that are possible.
1. Bromine substitution
2. Chlorine substitution
3. Nitro substitution
4. Alkyl Substitution
eg. of reaction 4
5. Side Chain Oxidation (No matter what is on the
side chain it will get removed leaving only a carboxylic acid.
eg. stryene is oxidized to benzoic acid