Oxidative C-C Bond Cleavage of Primary Alcohols and Vicinal Diols Catalyzed by H5PV2Mo10O40 by an Electron Transfer and Oxygen Transfer Reaction Mechanism

Primary alcohols such as 1-butanol were oxidized by the H5PV2Mo10O40 polyoxometalate in an atypical manner. Instead of C-H bond activation leading to the formation of butanal and butanoic acid, C-C bond cleavage took place leading to the formation of propanal and formaldehyde as initial products. The latter reacted with the excess 1-butanol present to yield butylformate and butylpropanate in additional oxidative transformations. Kinetic studies including measurement of kinetic isotope effects, labeling studies with O-18 labeled H5PV2Mo10O40, and observation of a prerate determing step intermediate by C-13 NMR leads to the formulation of a reaction mechanism based on electron transfer from the substrate to the polyoxometalate and oxygen transfer from the reduced polyoxometalate to the organic substrate. It was also shown that vicinal diols such as 1,2-ethanediol apparently react by a simialr reaction mechanism.