Stability of salicylamide-caffeine complex at different temperatures and its thermodynamic parameters

Abstract
The stability constants for formation of complexes of salicylamide with caffeine have been measured between 15 and 45°, by means of the solubility method. There was a linear solubility increase at all temperatures but phase diagrams indicated that at 15 and 25° an additional phase was formed which was found to be an insoluble 1: 1 complex. The enthalpies and entropies of interactions were evaluated. They indicate that the interaction is exothermic and enthalpy controlled.