Characterization of the decomposition course of Cu(II) 3,5-diisopropyl salicylate hydrate and chemical reactivity of the final products - Spectrothermal investigation

The thermal decomposition of Cu(II) 3,5-diisopropyl salicylate hydrate in dry nitrogen was studied thoroughly. Thermal events involved throughout the decomposition range (room temperature up to 600 degrees C) were monitored by means of thermogravimetry, differential thermal analysis and IR gas-phase analyses. The corresponding activation energy values were determined non-isothermally. Intermediate and final solid products were characterized by X-ray diffractometry and IR spectroscopy. The results showed Cu-2(C13H17O3)(4) . 8H(2)O melts at 115 degrees C, followed by the release of 8 mol of isopropyl alcohol (C3H7OH) to yield Cu-2(C7H5O3)(4) (copper salicylate) through two endothermic processes at 130 degrees C and 210 degrees C. Subsequently, the copper salicylate released phenol, CO and CO2 to give CuO as a final product at 250 degrees C. The IR spectra of the gaseous products revealed that a marked chemical reactivity of the gas/solid interface was present throughout the decomposition course. As a result, C3H7OH was involved in dehydrogenation/dehydration reactions over the freshly generated CuO surface, producing acetone and propene in the gas phase. Moreover, the byproduct acetone was involved in bimolecular interactions over the CuO surface, producing CH4 and (CH3)(2)C=CH2 (isobutene) in the gas phase.