How does conversion of a free radical to a carbonyl compound take place? Unsure about mechanism
You seem unsure about the homolysis between C1 and C2, but I speculate to consider the product's stability in this suggested reaction:



For one, two previously unpaired electrons form a $\pi$ bond in acetone.  For the other, you form a benzyl radical which may be described in more than one mesomeric form, for example for a radical bromination reaction of toluene.  Plus the neuter tropyl radical, the seven membered ring structure on the bottom right, result of a rearrangement.

Of course, the benzyl radical won't be persistent, eventually either looses a hydrogen, or combines with an other radical to form a closed shell molecule.