The Study Of Organic Catalytic Oxidation Reaction Of Polyoxometalates

Polyoxometalates(abbreviated as POMs)is a new type of multi-functional green catalysts,which not only absorb the advantages of the previous organometallic catalyst,but also has much superiority such as strong coordination ability,structure changeable and controllable,combining with acidity and oxidizing,and gradually become the research hotspot in the field of catalysis.By changing the composition and spatial structure of POMs,the introduction of other functional ligand with the combination of modified,to try to catalyze the different organic reactions,often able to get unexpected catalytic results.Epoxy compounds,aldehyde and sulfone compounds play an important role in organic synthesis chemistry and fine chemical production as three kinds of important oxidation products.Therefore,through the design and study of different types of POMs catalyst catalytic organic oxidation,and the use of hydrogen peroxide as a green oxidant,from the perspective of high efficiency and environmental considerations have important strategic significance.1.This chapter mainly explores the POMs catalytic oxidation of olefins.The catalysts include a series of lanthanide-containing peroxoisopolytungstates,a rare-earth-substituted organic-inorganic hybrid selenotungstate and a isotungstate-supported metal carbonyl derivative.The first two heterogeneous catalysts not only exhibit better catalytic activity for the oxidation of a variety of olefins,but also have recycle performance.While the third homogeneous catalyst exhibits extremely high catalytic activity for the oxidation of cyclooctene.By contrast experiments,we speculate that the catalytic active sites may be located on the W atoms in the POMs moiety of the catalyst.2.This chapter mainly explores the POMs catalytic oxidation of thioether.The catalysts include a transition-metal Mn centered polyoxovanadate and a phosphotungstate hexamers constructed by monolacunary Dawson-type and Pr ions.For polyoxovanadate,we chose TBHP as an oxidant instead of hydrogen peroxide,and obtained satisfactory catalytic results.Meanwhile,for rare earth praseodymium to participate in the construction of phosphotungstate catalyst,we investigated its catalytic oxidation ability for a variety of thioether compounds,and the catalyst did not show a significant decrease in activity after three cycles of catalysis.3.This chapter mainly explores the POMs catalytic oxidation of alcohol.The catalysts include a rare earth praseodymium to participate in the construction of isotungstate.The experimental results show that the catalyst exhibits a certain catalytic activity for various alcohols under the condition of acetonitrile as solvent and hydrogen peroxide as oxidant.