Thermodynamic Models for Determination of the Solubility of Boc-(R)-3-Amino-4-(2, 4, 5-trifluorophenyl)butanoic acid in Different Pure Solvents and (Tetrahydrofuran + n-Butanol) Binary Mixtures with Temperatures from 280.15 to 330.15 K

A gravimetric method was taken to measure the solubility of the Boc-(R)-3-amino-4-(2,4,5-trifluorophenyl)butanoic acid under atmospheric pressure in methanol, ethanol, propanol, n-butanol, ethyl acetate, and tetrahydrofuran as well as in the (tetrahydrofuran + n-butanol) mixtures from 280.15 to 330.15 K.The experiment results have proved that the rising temperature leads to increased solubility of the Boc-(R)-3-amino-4- (2,4,5-trifluorophenyl)butanoic acid in all selected solvents. The solid-liquid equilibrium data in pure and mixed solvents is correlated with a series of equations, including the modified Apelblat equation, the Buchowski-Ksiazaczak equation, CNIBS/R-K equation and the Jouyban-Acree equation. During the study, the computational values were in good agreement with the experimental results according to the calculations based on all selected equations, however, the modified Apelblat equation stood out to be the higher suitable with the higher accuracy. The thermodynamic properties of the solution process, including the Gibbs energy, enthalpy, and entropy were calculated by the vant Hoff equation. The calculated thermodynamic parameters indicated that in each studied solvent the dissolution process of Boc-(R)-3-amino-4-(2,4,5-trifluorophenyl)butanoic acid is endothermic.