Solubility Determination and Data Correlation of 4-Methoxybenzoic Acid in 14 Pure Solvents at Temperatures from 283.15 to 328.15 K

The solubility of 4-methoxybenzoic acid in 14 pure solvents (1-butanol, isobutanol, 2-butanol, 1-pentanol, ethylene glycol, ethyl formate, 1-propyl acetate, isopropyl acetate, n-butyl acetate, acetone, 2-butanone, cyclohexanone, toluene, and tetrahydrofuran) was determined through a gravimetric method at temperatures from 283.15 to 328.15 K. The experimental solubility showed an increasing trend with increasing temperature. Four thermodynamic models, including Modified Apelblat model, NRTL model, Van't Hoff model, and lambda h model, were selected to correlate the experimental solubility of 4-methoxybenzoic acid and further fit data. The results revealed that the calculated solubility from four models was in good correlation with the experimental data, with the Modified Apelblat equation providing the best fitting accuracy. Furthermore, the mixing thermodynamic properties of 4-methoxybenzoic acid in 14 pure solvents derived from the NRTL equation indicated that the mixing processes of 4-methoxybenzoic acid are spontaneous and entropy driven. In addition, the solvent properties were investigated to elucidate the solid-liquid equilibrium behavior of 4-methoxybenzoic acid in pure solvents.