Thermal decomposition of strontium and barium malonates

The thermal decomposition of strontium and barium malonates has been studied isothermally and non-isothermally employing simultaneous TG-DTG-DTA, DSC, XRD and IR spectroscopic techniques. DSC of these malonates has been recorded both in oxygen and nitrogen atmospheres. The decomposition is a single step process and the end product formed is carbonate. The energy of activation and frequency factor values for the decomposition of strontium malonate are 547 kJ mol(-1) and 10(41) s(-1) respectively. The activation energy and frequency factor values for isothermal dehydration of barium malonate sester-hydrate are 57-111 kJ mol(-1) and 10(7)-10(12) s(-1) respectively and the corresponding values for decomposition from DSC are 499.5 kJ mol(-1) and 10(44) s(-1) respectively. The higher thermal stability of strontium malonate as compared to that of barium salt is ascribed to its being anhydrous so that decomposition proceeds without restructuring. Their thermal stabilities have also been compared with that of respective oxalate salts.