Solubility Determination and Thermodynamic Correlation of 3-Amino-2-methylbenzoic Acid in 12 Monosolvents from 288.15 to 328.15 K

A gravimetric method is adopted to measure the solid-liquid equilibrium of 3-amino-2-methylbenzoic acid in different solvents, including methanol, ethanol, 1-propanol, isopropyl alcohol, 1-butanol, isobutyl alcohol, 2-butanol, methyl acetate, ethyl acetate, propyl acetate, water, and acetonitrile. Moreover, the experiment is carried out at atmospheric pressure, and the temperature range is from 288.15 to 328.15 K. The solid-liquid equilibrium of 3-amino-2-methylbenzoic acid in all used solvents increases with increasing temperature. In alcohol solvents, except for isopropyl alcohol and 2-butanol, the solubility of 3-amino-2-methylbenzoic acid is positively related to the polarity of the solvent, which follows the "like dissolves like" rule. Because isopropyl alcohol and 2-butanol possess a high hydrogen bond acceptor propensity, this leads to a different solubility behavior. In nonalcohol solvents, the solid-liquid equilibrium of 3-amino-2-methylbenzoic acid also follows the "like dissolves like" rule. Among all 12 solvents, the solid-liquid equilibria of 3-amino-2-methylbenzoic acid in water and acetonitrile are lower than those in alcohols and esters. In addition, the solid-liquid equilibrium data of 3-amino-2-methylbenzoic acid were related by the modified Apelblat equation, van't Hoff equation, and Ah equation. Furthermore, all relevant results show consistency with the solid-liquid equilibrium data of 3-amino-2-methylbenzoic acid.