abstracts - Институт катализа им. Г.К. Борескова

OP-II-20OXIDATION OF ORGANIC COMPOUNDS CATALYZED BYPOLYOXOPHOSPHOVANADOMOLYBDATE H 5 PV 2 Mo 10 O 40 : MECHANISTICINSIGHTSKhenkin A.M.Department of Organic Chemistry, Weizmann Institute of Science, Rehovot, Israel 76100E-mail: alex.khenkin@weizmann.ac.ilBetter understanding of homogeneous catalytic oxidation by molecular oxygen isfundamental to the design and functioning of green catalysts for selective oxidation. Amongsuch catalysts, polyoxometalates (POM) constitute a large and growing class of clasteranions,whose compositions, structures, and key properties are readily modified at themolecular level. One fundamental problem in the catalytic oxidation is that mosthomogeneous catalysts are partly organic in nature and thus thermodynamically unstable withrespect to CO 2 and H 2 O in the presence of O 2 whereas polyoxometalates remaining resistantto oxidative degradation. Although many types of polyoxometalate-catalyzed reaction arebeing reported, one compound that has been catalytically active in many liquid-phase reactionwith molecular oxygen has been the mixed agenda phosphovanadomolybdate,H 5 PV 2 Mo 10 O 40 . This compound catalyze oxidative dehydrogenation of dienes, alcohols,amines and phenols according to Scheme 1:Scheme 1S-H 2 + POMox S + 2H + + POMredPOMred + 2H + + 1/2O 2 POMox + H 2 OIn these cases, the substrates are oxydehydrogenated but not oxygenated.In this presentation will be reported of our finding that vanadium containing POMH 5 PV 2 Mo 10 O 40 can activate C-H bonds in aromatic and alkylaromatic compounds andoxygenate such substrates by a Mars - van Krevelen type mechanism. It will be also shownand discussed the evidence for the activation of the hydrocarbon substrate by electrontransfer, including observation of reaction intermediates, and present some insight on theoxygen-transfer step from the polyoxometalate to the activated hydrocarbon [1].232