Enthalpies of Dissolution of Diclofenac Sodium in Water and Aqueous Solutions of KOH at 298.15 K

Abstract

Enthalpies of dissolution of crystalline diclofenac sodium are measured in water and in aqueous solutions of KOH at 298.15 K via direct calorimetry in a wide range of concentrations. The acid–base properties of diclofenac sodium are studied via spectrophotometry at ionic strengths of I ~ 0 and I = 0.1 (KNO₃) and a temperature of 298.15 K. The concentration and thermodynamic dissociation constants are determined. The standard enthalpies of formation are calculated for diclofenac sodium, and for the products of its dissociation in an aqueous solution.