Solubility of rutaecarpine and evodiamine in (ethanol plus water) mixed solvents at temperatures from (288.2 to 328.2) K

The solubility of rutaecarpine and evodiamine was measured in (ethanol + water) mixed solvents with different values of mole fraction ethanol from (phi = 0.30 to 0.80) over the temperature range of (T = 288.2, 298.2, 308.2, 318.2 and 328.2) K. With increasing temperature and mole fraction ethanol, the solubility of rutaecarpine and evodiamine increased. The experimental solubility values were well correlated by the modified Apelblat equation, simplified thermodynamic equation and semi-empirical Buchowski-Ksiazczak lambda h equation. The correlated results by the modified Apelblat equation were better than those by other two equations. The enthalpy of dissolution (Delta H-dis degrees) and entropy of dissolution (Delta S-dis degrees) of rutaecarpine and evodiamine during the dissolution process in (ethanol + water) mixed solvents were calculated by the van't Hoff equation. The results indicate that the dissolution process is endothermic and entropy-driven. (C) 2014 Elsevier Ltd. All rights reserved.