Equilibrium Solubility and Dissolution Property Analysis of 2‑Nitrophenylacetic Acid in 13 Pure Solvents at Elevated Temperatures

This work was devoted to the equilibrium solubility of 2-nitrophenylacetic acid in 13 neat solvents ethylene glycol (EG), methanol, ethanol, acetonitrile, n-propanol, isopropanol, water, n-butanol, N,N-dimethylformamide (DMF), isobutanol, cyclohexane, ethyl acetate, and 1,4-dioxane ranging from 283.15 to 328.15 K. All determinations were made by the shake-flask technique at a pressure of p = 101.2 kPa. The mole fraction solubility magnitudes of 2-nitrophenylacetic acid increased gradually with the rising investigated temperature and presented a decreasing trend in the 13 neat solvents: DMF > (1,4-dioxoane, methanol) > ethanol (ethyl acetate) > n-propanol > n-butanol > isopropanol > EG > acetonitrile > isobutanol > water > cyclohexane. The method of linear solvation energy relationships was employed here to inspect the solvent–solvent and solute–solvent interactions. The solvent descriptors of the Hildebrand solubility parameter and polarizability/dipolarity presented great influence upon the solubility magnitudes of the solute 2-nitrophenylacetic acid. The obtained solubility values in mole fraction were correlated mathematically via four models/equations, namely, λh, non-random two-liquid, Apelblat, and Wilson. The maximum value of relative average deviation (RAD) was 3.68 × 10^–2, and the maximum value of root-mean-square deviations was 116.78 × 10^–4. The RAD values by using the Apelblat equation were smaller than that by using the other equations/models for a fixed solvent. Additionally, the dissolution properties, activity coefficient, and reduced excess enthalpy under the conditions of infinite dilution were obtained through the Wilson model.