Thermodynamic properties of hydrated sodium l-threonate Na(C4H7O5)·H2O(s)

Low-temperature heat capacities of the compound Na(C4H7O5)·H2O(s) have been measured with an automated adiabatic calorimeter. A solid–solid phase transition and dehydration occur at 290–318 K and 367–373 K, respectively. The enthalpy and entropy of the solid–solid transition are ΔtransHm = (5.75 ± 0.01) kJ mol−1 and ΔtransSm = (18.47 ± 0.02) J K−1 mol−1. The enthalpy and entropy of the dehydration are ΔdHm = (15.35 ± 0.03) kJ mol−1 and ΔdSm = (41.35 ± 0.08) J K−1 mol−1. Experimental values of heat capacities for the solids (I and II) and the solid–liquid mixture (III) have been fitted to polynomial equations.