Synthesis, characterization and the thermal decomposition of calcium(II)bis(oxalato)calcium(II)dihydrate

Article abstract of DOI:10.1016/0040-6031(96)02910-3

Calcium(II)bis(oxalato)calcium(II)dihydrate, Ca[Ca(C₂O₄)₂]·2H₂O, has been synthesized and characterized by elemental analysis, and reflectance and IR spectral studies. Thermal decomposition studies (TG, DTG, and DTA) in air showed that the final end product was CaO at 865°C through the intermediate formation of a mixture of CaCO₃ and CaO at approx. 818°C. At around 424°C a mixture of CaO and Ca(C₂O₄)_1.2 is formed by partial decomposition of oxalate which is stable up to 670°C. DSC studies up to 700°C in nitrogen at 10°C min^-1 showed both endothermic and exothermic peaks with activation energies of 190 and 458 kJ mol^-1, respectively, and compared with values calculated from TG. Some of the decomposition products were identified by spectral, analytical and X-ray powder diffraction studies and a tentative mechanism for the decomposition is proposed.