Thermodynamic properties of l-tryptophan

The energy of combustion of l-tryptophan at 298.15 K was determined by static-bomb isoperibolic calorimetry. The heat capacity of l-tryptophan was measured by vacuum adiabatic calorimetry over the temperature range from (7 to 373) K. A solid-to-solid transition is described. Smoothed values of the main thermodynamic functions for the crystal state over the temperature interval from 5 K to 370 K were calculated. The enthalpy of formation, entropy of formation and Gibbs energy of formation at 298.15 K of l-tryptophan in the solid state were computed on the basis of the experimental results obtained. All results are compared to experimental values reported in the literature.