Potentiometric Measurements of Ion-Pair Association Constants of Acids and Relative Strengths of Acids in Anhydrous Ethlenediamine and Water

Abstract

The ion-pair association constants of acids were determined from potentiometrical data obtained with the platinized platinum hydrogen electrode and saturated zinc chloride-zinc amalgam reference electrode. The investigation was also made in order to evaluate the behavior of acids in ethylene-diamine and to determine the acidity relationship between ethylenediamine and water solvents. The following relationship has been determined empirically: Below (pK_a)_H2O=7.0, (pK_a)_en=3.9; Above (pK_a)_H2O=7.0, (pK_a)_en= {3.9+(pK_a)_H2O}-7.0