Enzyme-like mechanism of selective toluene oxidation to benzaldehyde over organophosphoric acid-bonded nano-oxides

Abstract The completely selective oxidation of toluene to benzaldehyde with dioxygen, without the need to use H2O2, halogens, or any radical initiators, is a reaction long desired but never previously successful. Here, we demonstrate the enzyme-like mechanism of the reaction over hexadecylphosphate acid (HDPA)-bonded nano-oxides, which appear to interact with toluene through specific recognition. The active sites of the catalyst are related to the ability of HDPA to change its bonding to the oxides between monodentate and bidentate during the reaction cycle. This greatly enhances the mobility of the crystal oxygen or the reactivity of the catalyst, specifically in toluene transformations. The catalytic cycle of the catalyst is similar to that of methane monooxygenase. In the presence of catalyst and through O2 oxidation, the conversion of toluene to benzaldehyde is initiated at 70 dC. We envision that this novel mechanism reveals alternatives for an attractive route to design high-performance catalysts with bioinspired structures.