Solubility of benorilate in twelve monosolvents: Determination, correlation and COSMO-RS analysis

Abstract

Abstract The solubility of benorilate in twelve monosolvents (methanol, ethanol, n-propanol, isopropanol, n-butyl alcohol, isobutanol, ethyl formate, ethyl acetate, isopropyl acetate, methyl acetate, acetonitrile and acetone) was determined at temperatures ranging from 278.15\xa0K to 318.15\xa0K using a static method under atmospheric pressure. The solubility trend of benorilate has two features, one is that the solubility increases with rising temperature, the other is that benorilate generally has larger solubility in dipolar aprotic solvents than in polar protic solvents. Furthermore, three classical thermodynamic models (modified Apelblat model, λh model and NRTL model) were used to correlate these determined solubility data, and modified Apelblat model shows the minor deviation than other models. Moreover, three solution thermodynamic parameters of mixing process were analyzed on the basis of NRTL model, and the mixing process was found to be spontaneous and entropy-driven. This work also used COSMO-RS model to predict reasonable solubility data of benorilate with experimental thermal analysis method and reference solubility method respectively. The underlying mechanism of benorilate and solvent molecules in solubility behavior was qualitatively analyzed by physicochemical properties and sigma profiles of the studied systems. The molecular interaction energies of benorilate in the studied solvents were computed on the basis of COSMO-RS model, and the computed values were also used to quantitatively analyze interactions in solutions of benorilate. The results obtained by qualitative and quantitative analysis demonstrate that the solvation of benorilate is a complicated process which is subject to the combined effects of a variety of molecular interactions. This research could provide guidance for the crystallization process optimization of benorilate.