Influence of the conjugate anion on the parameters of ESR spectra in radical cations of sterically hindered hydroquinones

The reactions of hindered p-quinones and hydroquinones with inorganic, organic, and Lewis acids have been studied by ESR. The conjugate anion has a strong perturbing effect on the distribution of the spin density at the reaction center. A mechanism for the reduction of p-quinones and the oxidation of hydroquinones, which includes a step involving the formation of radical-cation salts, has been proposed. The form of the ESR spectra and the composition of the final products are greatly dependent on the ratio between the reactants, the medium, and the temperature.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 22, No. 6, pp. 737–741, November–December, 1986.