Aerobic Oxidation Catalysis by a Molecular Barium Vanadium Oxide

Aerobic catalytic oxidations are promising routes to replace environmentally harmful oxidants with O2 in organic syntheses. Here, we report a molecular barium vanadium oxide, [Ba4(dmso)14V14O38(NO3)] (={Ba4V14}) as viable homogeneous catalyst for a series of oxidation reactions in N,N‐dimethyl formamide solution under oxygen (8 bar). Starting from the model compound 9,10‐dihydroanthracene, we report initial dehydrogenation/ aromatization leading to anthracene formation; this intermediate is subsequently oxidized by stepwise oxygen transfer, first giving the mono‐oxygenated anthrone and then the di‐oxygenated target product, anthraquinone. Comparative reaction analyses using the Neumann catalyst [PV2Mo10O40]5− as reference show that oxygen diffusion into the reaction mixture is the rate‐limiting step, resulting in accumulation of the reduced catalyst species. This allows us to propose improved reactor designs to overcome this fundamental challenge for aerobic oxidation catalysis.