APPLICATION OF THERMAL ANALYSIS ON THE CHARACTERIZATION AND DETERMINATION OF STABILITY OF THE MOLECULE GUANYLHYDRAZONE WE010

摘要

WE010 is a molecule class of guanylhydrazones widely studied, biologically and chemically and there are not studies about thermal behavior. This study aimed to apply the thermal analysis: Differential Scanning Calorimetry (DSC), Differential Scanning Calorimetry coupled to Photovisual system (DSC-Photovisual) and Termogravimetry (TG), to characterize the WE010, as well as to use kinetics models of Ozawa and Arrhenius on the determination of the stability. DSC curves of the WE010 showed four endothermic transitions in the range 25-300°C, with melting process in 189-197 °C and heat of 41 J/g. The DSC-Photovisual showed impurities during melting process. The TG curves showed four consecutive steps of mass loss between 187-900°C. The results kinetics for WE010 showed zero order reaction for in first and main step of decomposition and activation energy about 90 kJ mol-1 and frequency factor of 5.6 × 10~8 min-1. The rate constants were calculated: 1.0E-07, 3.4E-07, 1.7E-06 and 5.0E-06 for the following temperatures 180, 190, 200 and 210°C, respectively. Therefore, the thermal analysis has proven to be an important analytical tool in thermal and kinetic characteristics that may be used in the development of formulation with therapeutic potential.