The effect of the medium polarity on the mechanism of the reaction of hydroxybenzenes with hydrazyl radical in aprotic solvents

Mechanisms of the reaction of di- and trihydroxybenzenes with 2,2′-diphenyl-1-picrylhydrazyl (stable radical) in aprotic media of different polarity have been elucidated by experimental and quantum-chemical methods. Kinetic, stoichiometric, and activation parameters of the reaction have been determined. In benzene (nonpolar solvent), the studied reaction occurs via the hydrogen atom transfer mechanism; in the polar solvent with weak ionizing ability (i.e. DMSO), the reaction predominantly occurs via the faster mechanism of coupled electron and proton transfer.