Thermodynamics of the thallium alkanoates. IX. Thermodynamics of thallium(I) n-octanoate from temperatures of 6 to 490 K

Abstract

The heat capacity of thallium(I) n-octanoate has been measured from 5 to 350 K by equilibrium adiabatic calorimetry and, taken together with DSC data determined earlier by a subset of the present authors, represents the thermodynamic behaviour in the liquid phase at about 500 K. Transitions occur at 269.8, 290.0, and 293.5 K, melting at 411 K, and clearing at 495 K. Except for a small ΔtrsS°m, the lowest temperature (269.2 K) phase transition (crystal IV/crystal III) has ΔtrsS° = 0.62 R, the higher temperature transitions (approx. 293.5 and 290 K) have ΔtrsS°m values for III/II/I of 3.97 R ((approximate partial resolution) III II ≅ 1.7 R and II I = 2.25 R), for crystal I mesophase (411 K) of 1.66 R, and for mesophase/isotropic liquid (495 K) of 0.73 R. © 1995.