If you look at this compound, only the benzylic carbon on the top has a hydrogen attached to it, so how do we oxidize only the top part without touching the lower one (not sure if this product is right), and what happens to the $\ce{-CH2}$ in the middle?
Also, does benzylic oxidation with $\ce{KMnO4}$ happen only with alkyl chains (R)? What if it had a carbonyl instead (a ketone let's say) or any other organic functional group attached to a benzene ring, what would happen to it? For example, Molecule Y here:
Why did it get oxidized to phthalic acid if the lower benzylic carbon doesn't have any hydrogen atoms attached to it?