Photo-oxidations of acetoin and biacetyl catalyzed by tetrabutylammonium decatungstate(4–) in acetonitrile under excess of oxygen
Abstract
Under an excess of oxygen, the photo-oxidation of acetoin catalysed by [NBu4]4[W10O32] and based on irradiation (λ > 300 nm) of the charge-transfer band in acetonitrile solution has been investigated. After irradiating for 30 h the products were biacetyl and acetic acid. The acetic acid was produced from both the acetoin and biacetyl. The rate constant for each path was determined by computer simulation. The production of biacetyl is based on dehydrogenation of acetoin in conjunction with the redox cycle of [W10O32]4– attained by reaction with O2 whereas the production of acetic acid from biacetyl is based on the photoexcitation of biacetyl complexed with [W10O32]4– and subsequent reactions with O2 and water.