Solid–liquid equilibria of chrysin in six pure solvents and in aqueous methanol mixtures: temperature dependence and thermodynamics

Using a UV spectrophotometric method, the solubility of chrysin, a bioactive compound, in six pure solvents (water, methanol, ethanol, butan-1-ol, butan-2-ol, and ethylene glycol) and various water + methanol mixtures was measured at atmospheric pressure 0.1 MPa. The measurements were carried out over the temperature range from 288.15 to 328.15 K at 5 K intervals. It was found that the solubility of chrysin in the pure solvents increases with increasing the temperature, while, in methanol + water binary solvents, the solubility positively correlates with temperature and the mole fraction of methanol. Experimental solubility data were correlated with the van’t Hoff equation, modified Apelblat equation, Yaws equation, and λh equation, which were thermodynamic models. Results showed that the four models could predict with the solubility data of chrysin in pure solvents and in methanol + water mixtures. Furthermore, the dissolution thermodynamic parameters of chrysin were calculated. The positive estimations of enthalpies revealed that the dissolution of the compound in the studied systems was an endothermic process.