Selective functionalization of n-hexane with molecular O2 catalyzed by immobilized Cu/Co, Cu/Fe and Co/V complexes on modified Al2O3

Heterobinuclear macrocyclic complexes, i.e. CuCoL 1, CuFeL 2 and CoVL 3, have been synthesized and anchored onto modified carbamate Al2O3 in order to obtain new hybrid supported catalysts. The identities of the supported metal complexes were confirmed by FT-IR, SEM-EDS and AAS. TGA indicated that the catalysts were thermally stable up to 230 degrees C. These catalysts have been tested for the functionalization of n-hexane with molecular O-2. The best result was obtained with CuFeL 2 over Al2O3 (ca. 19% overall conversion; 78% selectivity: hexan-2-one plus hexan-2-ol) and promoted conversion could be obtained with 2-pyrazin-ecarboxylic acid (as co-catalyst). The effects of various factors (temperature, O-2 pressure, reaction time and catalyst concentration) were also investigated in detail. The impact of both C- and O- centred radical traps was also assessed to establish a radical mechanism.