Sorarù, Antonio (2010) Ossidazioni sostenibili di substrati organici catalizzate da eteropolianioni. [Laurea specialistica biennale]
Full text disponibile come:
Nine novel Polyoxometalates (POM) have been studied as catalysts for sustainable oxidative process of organic substrates. Five peroxo ZrIV and HfIV POMs, three dimeric compound [M2(O2)2(α-XW11O39)2]12- (1-3) and two trimeric compound [M6(O2)6(γ-SiW9O36)3]18- (4-5), have been used for L-Methionine and D,L-Methonine sulfoxide oxidation, collecting kinetic traces of reactions by means of 1H-NMR spectroscopy. Stoichiometric and catalytic reactions have been carried out to get information on both the mechanism of the reaction and on the reaction scope. Compound 1-3 are very efficient for such reactions, yielding conversion of L-Methionine into D,L-Methonine sulfoxide of 90-99% in less than 1h and of D,L-Methonine sulfoxide into Methonine sulfone of 80-96% in 1,5-2h. Two Al-subtituted Krebs-type POM, [Al4(XW9O33)2]6- with X=As (tungstoarsenate 6) and X=Sb (tungstoantimonate 7), have been studied as catalysts for the oxidation of alcohols and alkenes with hydrogen peroxide in organic, halide-free solvent, yielding conversion of H2O2 of 19-99% in 1-2h. An interesting selectivity towards alcoholic functionalities has allowed to obtain high regioselectivity for the oxidation of hydroxyl group to the corresponding carbonyl, even in presence of alkene functionality. UV-Vis and CD analysis have been carried out to understand how the substrate may coordinate to the metal centre. Two Ru-substituited, Keggin-type polyoxometalates, with different apical ligands [Ru(L)(α-SiW11O39)] (L=H2O 8, L=DMSO 9) have been used as catalysts for the aerobic oxidation of alcohols, yielding carbonylic products with conversion of 13-14% in 50min. The stability of all compounds was confirmed by FT-IR and UV-vis analysis.
Solo per lo Staff dell Archivio: Modifica questo record