Solubility Determination and Thermodynamic Analysis of 2,4-Dichlorobenzoic Acid in 10 Pure Solvents and Three Binary Solvents at 273.15–318.15 K

2,4-Dichlorobenzoic acid (2,4-DCBA) plays a pivotal role in the synthesis of drugs and materials. Its solubility was meticulously determined using a static equilibrium method in conjunction with HPLC, across 10 individual solvents and three solvent mixtures. It can be found that 2,4-DCBA exhibited high solubility in alcohol solvents. Notably, in the acetone–acetonitrile system, solubility rose markedly with an increase in the positive solvent’s fraction. In the methanol, ethanol, and acetonitrile mixtures, the solubility of 2,4-DCBA peaked when the positive solvent’s molar fraction reached 0.8, suggesting that binary solvents can outperform single solvents in terms of dissolution. XRD and TG-DSC confirmed that 2,4-DCBA did not decompose, and its crystal structure did not change significantly during the experiment. The improved Apelblat model and λh model were used to fit and analyze the solubility data in a single pure solvent, and the CNIBS/R-K model, Jouyban–Acree model, and Sun model were used to process the solubility data in a binary solvent system. The reliability of the fitting results was confirmed by calculating the RAD and RMSD values of the thermodynamic models. Ultimately, the research utilized the KAT-LSER model to examine the impact of solvent characteristics on the solubility of 2,4-DCBA in individual solvents.