Formation and reactions of radical cations of substituted benzenes in aqueous media

Radical cations of anisole, methylated benzenes, ethylbenzene, isopropylbenzene, tert-butylbenzene and N,N-dimethylaniline were studied in aqueous media by pulse radiolytic technique. Absorption spectra and reaction kinetics of the radical cations were recorded. The radical cations are formed from the corresponding OH adducts by the elimination of OH-, either by a simple dissociation or by an acid catalyzed reaction. The rate constants of the formation of the radical cations and their reactions with water, OH- and Fe2+, or the reaction of a proton loss, were measured. The rate constants for the reaction with water and OH-, together with the rate constants for the dissociation of the OH adducts, are correlated with the ionization potential of the parent compound. These correlations offer a possibility of predicting the acid-base properties of radical cations of substituted benzenes, or the estimation of their ionization potential. (author)