Solvent dependence of the ionization of nitrophenylmethanes

Abstract

The solvent dependence of proton abstraction from various nitrophenylmethanes has been examined for aqueous dimethyl sulphoxide and methanolic dimethyl sulphoxide solutions. Even though the compounds studied vary considerably in thermodynamic acidity (pK_a), their proton-abstraction rates all show the same solvent dependence. It is suggested that the transition states for these reactions all occur at similar positions on the reaction pathway, and that transition state imbalances exist for these proton transfers.