I was taught that acidified KMnO4 can oxidise side chains of benzene to -COOH. There seems to be conflicting information on the conditions for this online. Some sources suggest that a benzylic H is required, while others suggest that either a benzylic H or O is sufficient. In particular, I'm not sure if benzylic ketones and 3° alcohols are oxidised. What are the actual conditions for the oxidation of side chains on benzene?