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

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, iso-propyl 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 x 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 thermo-dynamic 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.

Automated summary

This study reported the solubility and apparent thermodynamic properties of Adiphenine hydrochloride (ADH) (Form I) in twelve mono-solvents. The solubility of ADH (Form I) decreased with decreasing temperature in the same solvent. The NRTL model and modified Apelblat model showed better fitting to the experimental values of solubility. The dipolarity/polarizability of the solvent and the acidity of the hydrogen bonds positively influenced the solubility of ADH (Form I). The dissolution process of ADH (Form I) was found to be an entropy-driven endothermic process based on the van't Hoff equation.