Chinese Academy of Sciences, China
A joint theoretical and experimental study on the oxidation reactivity of glycerol catalyzed by chemically pure small Au clusters at the absence and presence of H2O2 was done. From high-resolution mass spectrometry, fruitful products of glyceraldehyde, glyceric acid, tartronic acid, mesoxalic acid and glycolic acid are observed pertaining to the successive Jones oxidation process associated with C-O and C–H bond activation. We then fully demonstrated the reaction pathways on a basis of complementary-active-sites mechanism, revealing the favorable dehydration of glycerol followed by oxidation to form glyceraldehyde and carboxylic acids at the presence of small Au clusters and H2O2. It is found that the Aun/H2O2 system undertakes a heterolytic mechanism by firstly transferring an O-atom from H2O2 to the Au cluster forming an active intermediate, on which the hydride abstraction and subsequent oxygen rebound become thermodynamically allowed, promoting the C-H insertion reaction and further oxidation of aldehyde to carboxylic acids.