Solubility Behavior and Polymorphism of N-Acetyl-DL-methionine in 16 Individual Solvents from 283.15 to 323.15 K

The mole fraction solubility data of N-acetyl-DL-methionine in 16 pure solvents at T = 283.15-323.15 K were measured using the static gravimetric method under a pressure of 98.8 kPa. The polymorphism of N-acetyl-DL-methionine was studied by X-ray powder diffraction analysis, and the results show that there may exist two polymorphs in the studied solid-liquid equilibrium systems. The solubility increased with increasing temperature, and the largest solubility value was obtained in methanol, followed by ethanol > n-propanol > isopropanol > n-butanol > sec-butanol > isobutanol > n-pentanol > acetone > 2-butanone > water > methyl acetate > ethyl acetate > dichloromethane (except for 1,4-dioxane and acetonitrile, which intersect with other solvents). The above solubility behavior is affected by the mutual constraints of polarity, hydrogen bonding, cohesive energy density, viscosity, and molecular structure. In addition, the KAT-LSER model was applied to analyze solute-solvent and solvent-solvent intermolecular interactions. To mathematically represent the measured solubility data, the modified Apelblat model and Yaws model were employed. The average relative deviation (ARD), root-mean-square deviation (RMSD), Akaike information criterion (AIC), and Akaike values of each model were calculated to evaluate the fitting outcomes.