Oxidative ring cleavage of 2,3-dihydrophthalazine-1,4-dione in aqueous and non-aqueous solutions: Electrochemical and kinetic studies

Abstract

Electrochemical oxidation of 2,3-dihydrophthalazine-1,4-dione (DHP) has been investigated in aqueous and some amphiprotic and aprotic non-aqueous solvents by cyclic voltammetric and controlledpotential coulometric techniques. Our data shows that electrochemically generated phthalazine-1,4-dione (PTD) in water and amphiprotic non-aqueous solvents participates in an oxidative ring cleavage (ORC) reaction to form phthalic acid. The rate of this reaction is dependent. On autoprotolysis constant (K SH ) and basicity of the solvent. Therefore, in the aprotic non-aqueous solvents such as acetonitrile and DMSO, the rate of ORC is too slow to be observed on the time-scale of cyclic voltammetry.