Determination of 2-Chlorocinnamic Acid Solubility in 16 Solvents: Model Correlation, Molecular Simulation and Solvent Effects Analysis

The solubility of 2-chlorocinnamic acid in 16 pure organic solvents, including alcohols, esters, ketones, toluene, and acetonitrile, was determined by the gravimetric method at 272.15–321.55 K under 101.3 kPa. Results showed that solubility of 2-chlorocinnamic acid increased with temperature in all solvents. To correlate the experimental data, five thermodynamic models, i.e., the modified Apelblat, Buchowski–Ksiazaczak λh, NRTL, Wilson, and Yaws equations, were employed. Model accuracy was evaluated using average relative deviation (ARD) and root-mean-square deviation (RMSD), and all models provided satisfactory correlations. In addition, electrostatic potential energy surface analysis was carried out to preliminarily assess possible solute–solvent interactions, while density functional theory (DFT) calculations were used to further examine molecular interactions during dissolution. The Kamlet–Abboud–Taft linear solvation energy relationship (KAT-LSER) model was applied to analyze solvent effects. Thermodynamic functions, including enthalpy, entropy, and Gibbs free energy of mixing, were calculated using the Wilson model. The results revealed that the dissolution of 2-chlorocinnamic acid in the studied solvents is an endothermic, entropy-driven, and spontaneous process, indicating favorable solute–solvent interactions and enhanced solubility at higher temperatures.