Thermal studies and decomposition kinetics of alkaline earth metal trichloroacetates

Abstract

Alkaline earth metal trichloroacetates M(O2CCCl3)2·nH2O, where M = Be (1), n = 4; M = Mg (2), n = 6; M = Ca (3) or Sr (4) or Ba (5), n = 4, were synthesized and their thermal behavior analyzed using thermogravimetric analysis (TG/DTG/DSC). A critical examination was made for the apparent activation energy by means of non-isothermal kinetic methods employing multiple heating rates. A systematic and comparative study of thermal decomposition was carried out at different heating rates i.e., 5, 10, 15, and 20 °C min−1 for various trichloroacetates synthesized. It was observed that the Ca, Sr, and Ba trichloroacetates decompose preferentially to respective metal halides while Be and Mg compounds decompose to metal and metal oxide, respectively. The composition of the final residues was also confirmed using FT-IR spectroscopy. The activation energy follows the order: Mg > Ca > Sr > Ba, Be being the exception. Results reveal that each metal trichloroacetate decomposes through its unique thermolysis mechanism.