"Polarographic and cyclic voltammetric reduction of N|-(benzenesulfonyl)-3-methyl-4-(2|-substituted-aryl hydrazono)-pyrazolin-5-ones was carried out in 40% (v/v) dimethylformamide in Britton-Robinson buffer solutions of pH 1.1-10.1. Thermodynamic parameters i.e. enthalpy of activation ‘∆H*p’, heat o...