Remarks and further calculations on the thermodynamic properties of enantiotropic polymorphs of glycolide

摘要

The dissolution thermodynamic properties of polymorphic glycolide in different organic solvents were researched by Huang and coworkers [J. Chem. Thermodynamics 111 (2017) 106-114]. The analysis of Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TG) indicated that glycolide form 1 has a phase transition between the experimental temperature and the melting point. It should be considered that the effect of phase transformation when calculating the activity coefficient of glycolide form 1 by NRTL model. Moreover, the dissolution properties, including Gibbs energy, enthalpy and entropy of form 1 and form 2 were not consistent with the formula (Delta H-dis - Delta G(dis) + T Delta S-dis) in published paper. In order to get a better understanding of solution behavior, we tried to further calculate and discuss the activity coefficient (gamma(infinity)(1)) and reduced excess enthalpy (HE1E,infinity) at infinite dilution of glycolide form 1 and form 2 in this work.