Spin Trapping of Radical Intermediates Generated by the Oxidation of Substituted 4‐Methylphenols

A series of substituted 4‐methylphenols 1 and 2 was oxidized with PbO 2 in the presence of nitroso compounds 3 – 10 . The formation of adducts of benzyl radicals with the nitroso spin traps in the reaction mixture was established, suggesting the abstraction of an H‐atom from the methyl substituent of 1 or 2 . In the consecutive steps, the adducts underwent a further rearrangement to the corresponding nitrones. When the starting phenol contained bulky t Bu groups in ortho ‐position (see 2,6‐di( tert ‐butyl)‐4‐methylphenol ( 1a )), the stable 2,6‐di( tert ‐butyl)‐4R‐phenoxy radicals (R=CHN + (O − )X) were detected as the final radical products. The indirect evidence of nitrones in the reaction mixture was performed in one case by the reaction with a RO $\rm{{_{2}^{{^\cdot} }}}$ radicals.