Thermodynamics Research Center / ThermoML | Journal of Chemical and Engineering Data

ABSTRACT

In this work, the solid-liquid phase equilibrium of N, N'-Diethylthiourea (DETU) was investigated in different solvent systems from both solid-state structure and solution thermodynamics. The single crystal structure of DETU was determined for the first time, and the intermolecular hydrogen bonding N-HS interactions are dominant in the crystal packing. The thermodynamic equilibrium solubility was determined by the gravimetric method in twelve solvents (methanol, ethanol, n-propanol, isopropanol, nbutanol, sec-butylalcohol, n-pentanol, acetone, butanone, methyl acetate, ethyl acetate, and acetonitrile) from 283.15 K to 323.15 K. It was found that the solubility in alcohols decreases with increasing the length of carbon chain and follows the rule of "like dissolves like", whereas in non-alcohol solvents the rule does not apply. The experimental data were further correlated by the modified Apelblat equation, h equation and NRTL model. All the correlation derivations are lower than 5%, and the NRTL model receives the best fitting performance. Furthermore, the thermodynamic functions of mixing including enthalpy, entropy, and Gibbs energy were derived, and the results expectedly suggest a spontaneous and entropy-driven mixing process. All the crystallographic and thermodynamic data reported in this study will provide the fundamental data for designing and optimizing the crystallization of DETU.