Abstract: | A radical-induced aromatic substitution mechanism for the reaction between benzoyl peroxide and benzenediols in the gas phase was characterized by mass spectrometry. The benzoyloxy radical produced from the homolysis of benzoyl peroxide associates at its carbonyl group with the phenolic hydroxyl group. The pairing tendency of the unpaired electron on the oxygen of the radical induces electron transfer along the hydrogen bond, which results in the rupture of the O? H bond of the phenol and aromatic substitution at the ortho position of the benzoyloxy radical. Supporting evidence for the mechanism was obtained by isotope labelling. |