Solubilities of Oleanolic Acid and Ursolic Acid in Different Organic Solvents and 2-Propanol + Water Binary Solvent Mixtures at Different Temperatures: Experimental Measurement and Modeling

The solubilities of oleanolic acid and ursolic acid in 1-butanol, methyl isobutyl ketone, methyl tert-butyl ether, and 2-propanol + water binary solvent systems at different temperatures were determined by a high-performance liquid chromatography analysis method. Various models were used to fit the solubility data; the results showed that the modified Apelblat mode can best fit the solubility data with temperature among the three modes (the modified Apelblat mode, the λh equation, and the van't Hoff equation), and the Ma model gave a better correlation of the solubility data with both the temperature and mole fraction of 2-propanol in the binary solvent mixture than the Sun model. The experimental solubility data and computational model can be useful for separation and purification of oleanolic acid and ursolic acid.