Correlation of solubility and prediction of the mixing properties of rosmarinic acid in different pure solvents and in binary solvent mixtures of ethanol + water and methanol + water from (293.2 to 318.2) K

The solubility of rosmarinic acid was measured in water, ethanol, methanol, and in the binary solvent mixtures (ethanol + water) and (methanol + water), with different molar fraction values for ethanol and methanol, from (Xsolv = 0.10 to 0.90), over a temperature range of (T = 293.15, 298.15, 303.15, 308.2, 313.15 and 318.15) K. With increasing temperature and molar fraction of ethanol and methanol, the solubility of rosmarinic acid increased from 0.26 to 0.46 and from 0.28 to 0.49 respectively. The experimental solubility values were well correlated by the modified Apelblat equation. From the measured solubility data, the thermodynamic properties enthalpy of dissolution (ΔsolHRA) and entropy of dissolution ( ΔsolSRA) of rosmarinic acid, during the dissolution process in water, ethanol, methanol, and binary solvent mixtures (ethanol + water) and (methanol + water), could be calculated based on these fits. The results indicate that the dissolution process is endothermic.