Thermodynamics Research Center / ThermoML | Journal of Chemical and Engineering Data

ABSTRACT

The heat capacities of N-benzyloxycarbonyl-l-3-phenylalanine were measured by means of a fully automated adiabatic calorimeter over the temperature range from (79 to 395) K. A solid-liquid phase transition corresponding to the melting process was observed. The temperature, the molar enthalpy, and entropy of the phase transition were determined to be 358.799 K, 31.787 kJ*mol-1, and 88.594 J*K-1*mol-1, respectively. The mole fraction purity of the sample used in the adiabatic calorimetric study was determined to be 0.9830 according to the Van t Hoff equation. Two equations of temperature dependence for heat capacities in the solid and liquid state are presented. The thermodynamic functions, (HT - H298.15K) and (ST - S298.15K), were calculated based on the heat capacity data in the temperature range from (80 to 400) K with an interval of 5 K. The standard molar enthalpies of combustion have been determined to be ?cHm0(C17H17NO4, s) = -(8308.52 +- 3.22) kJ*mol-1, with a precision oxygen-bomb combustion calorimeter at T = 298.15 K. The standard molar enthalpy of formation of the compound has been derived from the enthalpy of combustion, ?fHm0(C17H17NO4, s) = -(815.05 +- 0.67) kJ*mol-1. The thermal stability of the compound was further studied using TG and DSC, and a possible mechanism for thermal decomposition was suggested.