Investigation of the Solubility of 2-Amino-1,3,4-thiadiazole in 14 Kinds of Pure Solvents: Solid–Liquid Equilibrium Determination and Model Correlation

Solid–liquid phase equilibrium of 2-amino-1,3,4-thiadiazole (ATD) in 14 common pure solvents was determined by a static gravimetric method, including alcohol (methanol, ethanol, n -propanol, i -propanol, n -butanol, i -butanol, and s -butanol), ketones (acetone, 2-butanone, and cyclohexanone), amides ( N, N -dimethylformamide and N, N -dimethylacetamide), and other organic solvents (acetonitrile and 1,4-dioxane). Solubility of ATD in each pure solvent increases with increasing temperature and is higher in amide solvents. In straight-chain alcohols, the solubility of ATD is positively correlated with the polarity. Three theoretical models including the modified Apelblat model, Yaws model, and Van’t Hoff model are selected to fit the solubility data of ATD. Modified Apelblat model fitted the solubility data best with RAD and RMSD values less than 1.07 × 10 –2 and 4.38 × 10 –5, respectively. Hirshfeld and molecular electrostatic potential surface analyses were chosen to explain the interactions between molecules.