Original Articles
Chirag B. Patel, Bhavin B. Dha
Abstract
Thermal study of some biologically active aryl esters of bisphenol-C derivatives have been investigated using TG and DSC techniques under nitrogen atmosphere at the heating rate of 10ºC min-1. The nature and position of the substituents affected DSC transitions, thermal stability and kinetic parameters. DSC curves of all compounds showed endothermic transitions in the range 120-2570C and corresponding enthalpy change (ΔH) in the range 18- 58 kJmol-1. Aryl esters are thermally stable up to about 215-3750C and followed either a single or two steps degradation kinetics due to structural dissimilarity. They followed either fractional or integral order degradation kinetics. Different magnitudes of n, Ea and A suggested different degradation mechanisms. A large and negative magnitudes of ΔS* confirmed highly ordered transition states, while a large and positive magnitudes of ΔS*confirmed less ordered transition states.