Solid–liquid phase equilibrium and thermodynamics analysis of 2,2,2-trichloroacetamide in different solvent systems

The knowledge of solid-liquid equilibrium data and solution thermodynamics of 2,2,2-trichloroacetamide (TCAcAm) in different solvents are essential for its synthesis, purification and further theoretical studies. In this paper, the solubility of TCAcAm in fifteen mono solvents of methanol, ethanol, n -propanol, isopropanol, n -butanol, isobutanol , n -pentanol, isopentanol, 2-butanone, acetone, ethyl acetate , 2-pentanone, acetonitrile , methyl acetate and ethyl formate was obtained through a gravimetric method at the temperature from 272.15 to 324.15 K under ambient pressure. The mole fraction solubility of TCAcAm in mono solvents showed an increasing trend with increasing temperature, and the phase equilibrium data in ketones and esters was much larger than that in alcohols. The experimental solubility can be well correlated using several thermodynamic models, such as the modified Apelblat equation, λh equation, non-random two-liquid (NRTL) model and the Wilson model. The obtained maximum relative average deviation ( RAD ) and root-mean-square deviation ( RMSD ) were 6.02 × 10 −3 and 2.086 × 10 −3 respectively. Besides, the dissolution enthalpy, entropy, and Gibbs free energy were calculated on the basis of thermodynamic relations and the Wilson model, which revealed that the dissolution of TCAcAm was a spontaneous and endothermic process.