Photo-Driven Aerobic Methane Nitration.

Conversion of methane to liquid oxygenates is challenging but of great value. Here, we report the oxidation of methane (CH) to methanol (CHOH) assisted by nitrogen dioxide (NO) as a photo-mediator and using molecular oxygen (O) as the terminal oxidant. Similar photoreactions are widely studied in atmospheric chemistry but were not previously used in preparative methane conversion. We used visible light to excite NO generated by heating aluminum nitrate Al(NO) and drove its reaction with methane and O to produce methyl nitrate (CHONO), which is then hydrolyzed to CHOH. Nitric acid (HNO) and nitrate (NO) were produced and recycled back to Al(NO), completing a chemical loop. HCl can catalyze this photochemical process via relay hydrogen atom-transfer reactions, with up to 17% methane conversion and 78% CHONO selectivity. This simple photochemical system provides new opportunities in selective methane transformation.