Solid-liquid phase equilibrium of adiphenine hydrochloride in twelve pure solvents

Abstract

The solubility and apparent thermodynamic properties of Adiphenine hydrochloride (ADH) (Form I) in twelve mono-solvents including methyl acetate, ethyl acetate, n-propyl acetate, n-butyl acetate, n-amyl acetate, isopropyl acetate, isobutyl acetate, n-hexanol, n-heptanol, n-octanol, anisole and acetone were reported in this work. The solubility of ADH (Form I) was quantified by the laser monitoring method at atmospheric pressure and the selected temperature ranged from 278.15 K to 323.15 K. In the same solvent, the lower the temperature is, the less the solubility of ADH (Form I) is. A maximum mole fraction solubility of ADH (Form I) existed in n-hexanol (0.2241) at 323.15 K while the minimum mole fraction solubility (1.139 × 10−4) appeared in isopropyl acetate at 278.15 K. The experimental values of solubility were fitted by modified Apelblat model, NRTL model and UNIQUAC model, and it was found that the calculated values of the NRTL model and the modified Apelblat model were closer to the experimental values. The dipolarity/polarizability of the solvent and the acidity of the hydrogen bonds both play a positive role in increasing the solubility of ADH (Form I). The apparent thermodynamic properties of the dissolution process of ADH (Form I) were analyzed by the van't Hoff equation. It can be found that the dissolution process is an entropy-driven endothermic processes.