Direct Synthesis of Acetone by Aerobic Propane Oxidation Promoted by Photoactive Iron(III) Chloride under Mild Conditions

Abstract

C–H activation of hydrocarbons is extremely challenging, especially in short-chain hydrocarbons like propane. In industry, propane is first converted to propylene mostly by steam cracking, which is only oxidized to acetone in the cumene process, yielding acetone and phenol. In this work, we show that the simple FeCl3 salt in acetonitrile photocatalyzes the oxidation of propane to acetone at room temperature under aerobic conditions and visible-light irradiation. We achieved 100% conversion of propane with 67% selectivity in acetone after 4 h of irradiation and TON up to 600. Mechanistic studies, including electrospray ionization mass spectrometry, Mössbauer, and electroparamagnetic resonance spectroscopy, concluded that the reaction is driven by chlorine radicals generated by Fe–Cl bond photolysis. These results not only hold promise for the development of solar-based oxidation of hydrocarbons but more importantly also disclose deeper insights into the largely overlooked photochemistry of FeCl3.