Solid-liquid phase equilibrium of SOV-I2 in various pure and binary mixed solvents: Solubility determination, solvent effect, preferential solvation and model correlation

Abstract

The solubility knowledge is important in the field of separation and purification of chemicals as well as quality control of drugs. In this work, the saturated phase equilibrium of SOV-I2 in ethanol, 1-butanol, acetone, methanol, 1-propanol, acetonitrile, toluene, 2-propanol, ethyl acetate, water, ethanol + water and acetone + water at a series of temperature of 278.15 K-318.15 K was constructed and the solubility data was measured by using isothermal saturation methods. The solvent effect evaluation, preferential solvation discussion and model correlation were used to explore the solubility behavior of SOV-I2. The solubility of SOV-I2 in mole fraction increased with the increasing of temperature. The experimental solubility data of SOV-I2 in mole fraction showed a subsequence in acetone > ethyl acetate > toluene > acetonitrile > methanol > ethanol > 1-propanol > 2-propanol > 1-butanol > water. For SOV-I2 + aqueous mixtures systems, the solubility data raised with the adding of co-solvents and no co-solvency phenomenon appeared in the dissolution process of SOV-I2 in two aqueous mixtures. The solvent effect was analyzed by KAT-LSER model which suggested that interaction of nonspecific dipolarity/polarizability played a dominant role in SOV-I2 dissolution. The solute–solvent interactions, accounted for>60%, were very important in dissolution of SOV-I2. Furthermore, the preferential solvation mechanism of SOV-I2 in two aqueous mixtures was discussed by IKBI method. The negative preferential solvation parameter (δx1,3) exhibited in the region of < x1 < 0.24 for ethanol (1) + water (2) mixtures and 0 < x1 < 0.21 for acetone (1) + water (2) mixtures. It suggested that SOV-I2 (3) was dissolved by water (2) preferentially in water-rich region. However, in other regions, the δx1,3 values were positive which indicated that SOV-I2 (3) was dissolved by co-solvents (1, ethanol or acetone) preferentially. In addition, the classical Apelblat, λh, Jouyban-Acree and Apelblat-Jouyban-Acree models were used to correlate the solubility data of SOV-I2. The correlation results showed that the greatest values of RAD and RMSD were 0.94% and 0.68 × 10-4 for pure solvent systems, and 2.10% and 2.14 × 10-4 for two aqueous mixtures systems, respectively. The evaluation indexes were quite small. In brief, these models showed a good applicability to experimental solubility data of SOV-I2.