Thermodynamics and kinetics of decomposition processes for standard α-amino acids and some of their dipeptides in the solid state

Abstract

Thermodynamic and kinetic data of the thermal decomposition process of the “standard” α-amino acids in the solid phase are presented in this work and correlated with the features of the four classes into which these compounds are classified in the liquid phase. The thermal stability of the components of the various classes is mainly linked to the decarboxylation process which, in turn, is influenced by the side-chains. The heat effects of the chemical processes and physical transitions, and the kinetic quantities of the decomposition processes of these compounds are presented. Three series of dipeptides have also been studied in the solid phase. In the first series, the mutual influence of two α-amino acids makes the dipeptides less stable than the independent free components. In the second, the methyl group plays a fundamental role in the thermal stability just as it does in the liquid phase where it is the key factor in the mutual influence of the different dipeptide structures. Finally, in the third class, a symmetrical system averages the thermodynamic quantities of the components.