Heteronuclear Macrocyclic Iron−Copper Complex Catalyst Covalently Bonded to Modified Alumina Catalyst for Oxidation of Cyclohexane

In this paper, we report the synthesis of FeCuL1 and FeCuL2 complexes of 2,6-diformyl-4-methylphenol and 1,2-phenylenediamine (L1) and 2,6-diformyl-4-methylphenol and 1,3-diaminopropane (L2). The FeCuL1 complex has been covalently bonded to alumina and used as a catalyst for the oxidation of cyclohexane. The complex catalyst thus-prepared was found to be thermally stable and was completely characterized by CHN, scanning electron microscopy−energy dispersive X-ray analysis (SEM−EDAX), thermogravimetric analysis (TGA), Fourier transform infrared (FTIR), and NMR spectroscopy. The oxidation of cyclohexane has been carried out using molecular oxygen without any solvent, coreactant, or cocatalyst in the temperature range (398−483 K) with cyclohexanone as the only product. The GC-MS of the product formed showed the total conversion was as much as 7.7%. In order to explain the experimental data, a possible reaction mechanism has been proposed and rate constants (assuming single phase) at different temperatures were determined using an optimal curve fitting by applying genetic algorithm. The rate constants thus-determined were found to be functions of temperature only. From experiments carried out at different temperatures, we found that, for every rate constant, an Arrhenius-type relation could be established.