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

Abstract

Heterobinuclear macrocyclic complexes, i.e. CuCoL 1, CuFeL 2 and CoVL 3, have been synthesized and anchored onto modified carbamate Al 2 O 3 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°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 Al 2 O 3 (ca. 19% overall conversion; 78% selectivity: hexan-2-one plus hexan-2-ol) and promoted conversion could be obtained with 2-pyrazinecarboxylic 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.