Reactions of lead tetra-acetate. Part XII. The oxidation of triphenyl-methanol and p-anisyldiphenylmethanol

Abstract

The triarylmethanols, ArPh₂C·OH (Ar = Ph or p-anisyl) undergo oxidative rearrangement when heated with lead tetra-acetate in acetonitrile, acetic acid, or benzene. Evidence is adduced that reaction in the first two solvents is predominantly by an ionic mechanism and that reaction in benzene is predominantly by a free-radical chain mechanism, which occur through the heterolysis and homolysis, respectively, of the O–Pb bond of the alkoxy-lead derivative. The radical rearrangement can be initiated by Perkadox (di-isopropyl peroxydicarbonate), and, in benzene, it is inhibited by p-benzoquinone. Unexpectedly, p-benzoquinone, nitrobenzene, or carbon tetrabromide catalyse the radical reaction in acetonitrile; a reason for this is suggested in the light of other observations.