Catalytic oxidation of para-substituted phenols with nitrogen dioxide and oxygen

Article abstract of DOI:10.1016/S0040-4039(98)00242-1

A series of para-substituted phenols was oxidized to the corresponding benzoquinones in moderate to high yield with catalytic amounts of NO₂ under O₂ in MeOH. Little or no oxidation is observed under argon. Substrates of lower reactivity gave quinones when treated with stoichiometric amounts of NO₂ in CCl₄, but nitration of the aromatic ring became a significant side product.