Solubility measurement, thermodynamic correlation and molecular simulations of uracil in (alcohol + water) binary solvents at (283.15–318.15) K

Abstract

The solubility of uracil in binary solvent mixtures, including (methanol + water), (ethanol + water) and (isopropanol + water), was determined from 283.15 K to 318.15 K by the ultraviolet spectroscopic method. It was shown by experiments that when the composition of solvent is constant, the solubility of uracil increases with the temperature. And the solubility of uracil in the binary solvent mixtures ranges as: (isopropanol + water) > (ethanol + water) > (methanol + water). Under isothermal conditions, as the mole fraction of organic solvent increases, the solubility of uracil increases first and then decreases gradually. To further verify the observed phenomena, the molecular simulations, including molecular electrostatic potential surface, Hirshfeld surface analysis and solvation free energy were provided. Besides, the modified Apelblat equation, λh model, CNIBS/R-K model, Jouyban-Acree model and NRTL model, were selected to correlate the experimental data, respectively. The results indicated that all selected thermodynamic models have good accuracy. Furthermore, the standard thermodynamic properties of the mixtures, including Gibbs energy, entropy and enthalpy were calculated and discussed, which indicated that the dissolution of the uracil in these three binary solvent mixtures is spontaneous and endothermic. All the results presented in this paper have some reference value to the further study of uracil.