Abstract In this paper, the theophylline (TP)-nicotinamide (NCT) cocrystal formed by intermolecular hydrogen bond was used as an example for studying the thermodynamic analysis of cocrystal. The solubility and solubility product (Ksp) of theophyllinenicotinamide cocrystal in isopropanol were measured at 298.15 and 308.15 K at atmospheric pressure. The solubility data shows that significant complexation occurs in some solutions, and the relevant constant K11 is derived. The dependence of cocrystal solubility on the concentration of cocrystal components in solution were measured and explained by a cocrystal solubility product and by the binding constants of complexes formed in solution. The effect of temperature on solubility product and complex constant was also discussed. In order to investigate how the cocrystals crystallized at different temperature, the ternary phase diagrams for theophyllinenicotinamideisopropanol at 298.15 and 308.15 K were constructed and the variation tendency with temperature was discussed. The ternary phase diagrams help us understand how the cocrystal was crystallized from solution and provides theoretical basis for crystallization process.
GUO Jing-Jing, DANG Le-Ping, WEI Hong-Yuan.Solid-Liquid Phase Equilibrium and Phase Diagram for Ternary TheophyllineNicotinamideIsopropanol System at 298.15 and 308.15 K[J] Chemcial Industry and Engineering, 2014,V31(5): 49-53
2014, Vol. 31 
