Thermodynamics of solubility of thiomalic acid in different organic solvents from 278.15 K to 333.15 K

• The solubility of thiomalic acid in different solvents was investigated.
• The modified Apelblat equation was more accurate than the λh equation and the van’t Hoff equation.
• Acetonitrile had the potential as a better solvent in the recrystallization process of thiomalic acid.
• The solution process in the selected solvents was endothermic and nonspontaneous.

The solubility of thiomalic acid was measured in methanol, ethanol, 2-propanol, 1-butanol, acetone, acetonitrile, and ethyl acetate in the temperature range between 278.15 K and 333.15 K under atmospheric pressure by gravimetric method. The solubility of thiomalic acid in those selected solvents increased with increasing temperature. The solubility data were correlated using the simplified molecular thermodynamic equation, the modified Apelblat equation and the semi-empirical Buchowski–Ksiazczak λh equation. The thermodynamic properties of the solution process, including the Gibbs energy, enthalpy, and entropy were calculated by the van’t Hoff analysis and the Gibbs equation. The experimental results showed that acetonitrile had the potential as the better solvent in the recrystallization process of thiomalic acid.