A bio-inspired Fe(III) complex and its use in the cyclohexane oxidation

The use of monooxygenase biomimetic catalysts has demonstrated good efficiency in the hydrocarbon oxidation. In this work we have used the complex [FeIII(HBPClNOL)(Cl)2]·H2O as catalyst in the cyclohexane oxidation and the products cyclohexanol, cyclohexanone and adipic acid were obtained. Cyclohexyl hydroperoxide and the tert-butyl cyclohexyl peroxide were also obtained as byproducts. The best reaction condition was reached with the system H2O2–acetonitrile at 50 °C, with 26.9% of yield. The investigation of the catalysis over time showed that the yields increase until 24 h, although the reaction rate is greater in the first 6 h. The electronic spectra of the complex were measured during the cyclohexane oxidation and it was possible to verify the disappearance of the bands assigned to the charge transfer from the phenolate and the chloride ligands to the iron. This indicates that electronic and/or structural changes are happening with the iron compound, confirming the existence of interaction between the complex and the oxidant.