Solubility of 2-Amino-5-chloro-3-methylbenzoic Acid in Ten Pure Solvents and Three Groups of Binary Mixed Solvents at T = 278.15-323.15 K

In this paper, the solubility of 2-amino-5-chloro-3-methylbenzoic acid under 0.1 MPa atmospheric pressure and temperature T = 278.15-323.15 K was determined by gravimetric analysis. Considering the safety and the cost of solvents, we selected the following 10 pure solvents and three binary mixed solvents: methanol, ethanol, n-butanol, acetone, acetonitrile, ethyl acetate, n-propanol, isopropanol, xylene, and n-hexane (n-hexane + acetone), (acetonitrile + acetone), and (methanol + acetone). The aim is to find suitable solvent systems for the recrystallization of 2-amino-5-chloro-3-methylbenzoic acid. The results indicate that the solubility of 2-amino-5-chloro-3-methylbenzoic acid is positively correlated with temperature, and the solubility of 2-amino-5-chloro-3-methylbenzoic acid is better in acetone. The modified Apelblat model, the Buchowski-Ksiazaczak λh model, the Redlich-Kister (CNIBS/R-K) model, and the Jouyban-Acree model were used to fit the solubility data of 2-amino-5-chloro-3-methylbenzoic acid in different solvents, and the experimental values were in good agreement with the calculated values. By comparing the four models, the modified Apelblat model was found to have a good correlation in pure solvents, and the Redlich-Kister (CNIBS/R-K) model was more suitable than the other two models in binary mixed solvents.