Photo- and Solvent-Mediated Production of the Highly Reactive N-Oxyl Radical and Its Efficient Catalytic Oxidation of Hydrocarbons at Ambient Temperature

Selective oxidation of hydrocarbons with molecular oxygen at ambient temperature is full of challenge, and efficient activation of the inert C-H bond under mild conditions is the breakthrough point. Due to the promotion effect of the organic solvent hexafluoroisopropanol (HFIP) and alpha-Fe2O3, highly reactive phthalimide-N-oxyl radical (PINO) species were produced under the photoirradiation of blue light (455 nm, 3 W) without additional heating, which were utilized to activate various aromatic hydro-carbons. Combining with the hyperoxide decomposition catalysis, the excellent conversion (98%) and the total selectivity (99%) to the ketone (aldehyde) and alcohol were successfully obtained at the ambient temperature of 30 degrees C. It was found that the reactivity and lifetime of PINO was closely related with the adsorption attitude of PINO on the surface of alpha-Fe2O3, which could be modulated to be most beneficial for the catalytic efficiency by relying on the homogeneous interaction between PINO and HFIP and the heterogeneous interaction between PINO and the surface of alpha-Fe2O3.