Trimethylamineborane and triethylamineborane: low-temperature thermodynamic properties

Abstract

The low-temperature thermal properties of trimethylamineborane and triethylamineborane were determined by adiabatic calorimetry over the range 12 to 390 K and 12 to 310 K, respectively. The quantities measured include the heat capacity of the condensed phases, enthalpies of transition, transition temperatures, enthalpies of fusion, and triple-point temperatures. The results were used to calculate the following thermodynamic functions at selected temperatures for the solid and liquid phases: (G s − H 0 o) T , (H s − H 0 o) T , H s − H 0 o , S s, and C s. Third law entropies and Gibbs energies of formation in the ideal gas state at 298.15 K for both compounds were computed from the results together with vapor pressures and enthalpies of formation from the literature.