Influence of acidity level in acetonitrile on Hammett–Zuman type correlations on the reduction of α-hydroxyquinones

Abstract

In this work the voltammetric study in acetonitrile was carried out of a quinones family containing α-hydroxy group, anilineperezones (APZs; 2-(1,5-dimethyl-4-hexenyl)-3-hydroxy-5-methyl-6-[4′-(R 2-phenyl)amine]-1,4-benzoquinones) as well as their comparison with their methylated derivatives (APZms; 2-(1,5-dimethyl-4-hexenyl)-3-methoxy-5-methyl-6-[4′-(R 2-phenyl)amine]-1,4-benzoquinones) where R 2 is MeO, Me, H, Br and CN. Through a systemic study that modified the type of electron transfer coupled reactions of the two quinoid systems, linear Hammett–Zuman type variations were found, Δ E pc= E pc(R 2=X)− E pc(R 2=H)= ρ π σ p+ a, with a≠0. Therefore, we suggest that the Hammett–Zuman equation simultaneously considers the substituent effect, not only in the electron transfer but also in chemically coupled reactions. Furthermore, we suggest that the magnitude of a of Hammett–Zuman type correlations shows the presence of chemical reactions coupled to the electron transfer, so that a apparently depends on the substituent effect on this type of reactions.