Thermodynamics Research Center / ThermoML | Journal of Chemical Thermodynamics

Estimation and confirmation of the thermodynamic stability relationships of the enantiotropic polymorphs of glycolide

Li, Yang, Yin, Qiuxiang, Huang, Qiaoyin, Guo, Mingxia, Hao, Hongxun, Lou, Yajing, Su, Nannan, He, Meng, Wang, Yongli
J. Chem. Thermodyn. 2018, 118, 26-33
ABSTRACT
The polymorphism of glycolide has been investigated. Form 1 and Form 2 of glycolide have been identified and characterized by X-ray powder diffraction (XRPD). Differential scanning calorimetry (DSC) and thermogravimetry (TG) analyses were carried out to study the thermodynamic stability relationships and the transition of the two forms of glycolide. Based on the heat of transition rule, Form 1 and Form 2 were determined as an enantiotropic system. The solubility measurements were done at 310.15 K under atmospheric pressure (0.1 MPa) by using the isothermal gravimetrical method for form 1 in this work. According to the solubility data of glycolide Form 1 and Form 2 in ethyl acetate, 1-propanol, 2- propanol, ethanol and 1-butanol, the transition temperature was then estimated by solubility extrapolation method, heat of transition (DHtr) method and confirmed by isothermal transformation method at (308.35 +- 0.5) K. Among these three methods, the isothermal transformation method provided the most accurate transition temperature with the help of suspended-transformation experiments monitored by online Raman spectroscopy.
Compounds
# Formula Name
1 C4H4O4 1,4-dioxane-2,5-dione
2 C4H8O2 ethyl acetate
3 C3H8O propan-1-ol
4 C3H8O propan-2-ol
5 C2H6O ethanol
6 C4H10O butan-1-ol
Datasets
The table above is generated from the ThermoML associated json file (link above). POMD and RXND refer to PureOrMixture and Reaction Datasets. The compound numbers are included in properties, variables, and phases, if specificied; the numbers refer to the table of compounds on the left.
Type Compound-# Property Variable Constraint Phase Method #Points
  • POMD
  • 1
  • Triple point temperature, K ; Crystal 2
  • Crystal 2
  • Crystal 1
  • Air at 1 atmosphere
  • DSC
  • 1
  • POMD
  • 1
  • Molar enthalpy of transition or fusion, kJ/mol ; Crystal 2
  • Crystal 2
  • Crystal 1
  • Air at 1 atmosphere
  • DSC
  • 1
  • POMD
  • 2
  • 1
  • Mole fraction - 1 ; Liquid
  • Temperature, K; Liquid
  • Pressure, kPa; Liquid
  • Liquid
  • Crystal 2 - 1
  • Gravimetric method
  • 1
  • POMD
  • 3
  • 1
  • Mole fraction - 1 ; Liquid
  • Temperature, K; Liquid
  • Pressure, kPa; Liquid
  • Liquid
  • Crystal 2 - 1
  • Gravimetric method
  • 1
  • POMD
  • 4
  • 1
  • Mole fraction - 1 ; Liquid
  • Temperature, K; Liquid
  • Pressure, kPa; Liquid
  • Liquid
  • Crystal 2 - 1
  • Gravimetric method
  • 1
  • POMD
  • 5
  • 1
  • Mole fraction - 1 ; Liquid
  • Temperature, K; Liquid
  • Pressure, kPa; Liquid
  • Liquid
  • Crystal 2 - 1
  • Gravimetric method
  • 1
  • POMD
  • 6
  • 1
  • Mole fraction - 1 ; Liquid
  • Temperature, K; Liquid
  • Pressure, kPa; Liquid
  • Liquid
  • Crystal 2 - 1
  • Gravimetric method
  • 1