2021 Volume 61 Issue 5 Pages 308-311
Heat capacities of four ketohexoses, fructose, sorbose, psicose, and tagatose, were measured by adiabatic calorimetry in the temperature range from ca.10 to 330 K. For sorbose, thermal anomalies were detected: 199.5 K (main phase transition of order-disorder type), around 210 K (minor ones), and ca. 120 K (glass transition). Although no heat anomaly was observed for the other three ketohexoses, their standard thermodynamic functions were estimated from the measured molar heat capacities. A spectral analysis using Kieffer’s model was applied to the heat capacities to rationalize the relation among them in terms of intra- and intermolecular hydrogen bonds in crystal.
