INFRARED OBSERVATION OF THE CHEMICAL CONSEQUENCES OF COBALT CATALYST PRODUCED IN MIXED-SOLUTIONS OF AL(ET)(3) AND CO(ACAC)(2)

Cobalt catalysts obtained from the reduction of Co(acac)(2) with Al(Et )(3) have been studied by infrared spectroscopy (in the selective hydr ogenation of multifunctional compounds). These solids prepared in situ were in suspension in a liquid mixture containing solvent and reagent . In order to obtain information on the preparation and the compositio n of the catalyst we carried out an FT-IR characterization using a spe cial device warranting sample manipulation in air-free atmosphere. At room temperature there were instantaneous and reductive ligand-exchang e between Al(Et)(3) and Co(acac)(2) and formation of Co-0 particles, C o-0 soluble complexes and Al(Et)2(acac). The multistep process may be initiated through the formation of a donor-acceptor complex ((acac)Co( acac) --> Al(Et)(3)). The presence of CO in the gas phase (H-2) when h eating the reaction mixture up to 180 degrees C enhances the reduction of cobalt and probes Co-0 in different coordination symmetries. Some of the Co-0 species could be surrounded with cobalt alkoxide species a nd aluminium acetylacetonate.