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.