RESUMO
Fluorophilic polyoxotungstates perform the selective epoxidations of internal and terminal double bonds by hydrogen peroxide (H2O2) activation in 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP), under mild temperature conditions. A hybrid synergy of supramolecular interactions, involving the inorganic cluster and the fluorinated solvent, is envisaged to boost H2O2 activation and the oxygen transfer mechanism. 1,2-Epoxides have been obtained with >99% selectivity and 98% yield at T = 40-70 °C.
RESUMO
Anchoring terminal octenyl tails on molecular polyoxotungstates yield polymerizable organic-inorganic monomers with formula [{CH(2)=CH(CH(2))(6)Si}(x)O(y)SiW(w)O(z)](4-) [x = 2, w = 11, y = 1, z = 39 (1); x = 2, w = 10, y = 1, z = 36 (2); and x = 4, w = 9, y = 3, z = 34 (3)]. These molecular hybrids can use aqueous hydrogen peroxide to catalyze the selective oxidation of organic sulfides in CH(3)CN. Copolymerization of 1-3 with methyl methacrylate and ethylene glycol dimethacrylate leads to porous materials with a homogeneous distribution of the functional monomers, as indicated by converging evidence from FTIR spectroscopy and electronic microscopy. The catalytic polymers activate hydrogen peroxide for oxygen transfer, as demonstrated by the quantitative and selective oxidation of methyl p-tolyl sulfide, which was screened as model substrate. The hybrid material containing monomer 2 was also tested in n-octane to evaluate its potential for the oxidation and removal of dibenzothiophene, a well-known gasoline contaminant.
RESUMO
The oxygen evolving catalyst [Ru(4)(µ-OH)(2)(µ-O)(4)(H(2)O)(4)(γ-SiW(10)O(36))(2)](10-) effects H(2)O(2) dismutation at rates (k = 36.8 ± 1.4 M(-1) s(-1)), one/two order of magnitude higher compared to related tetra-substituted Cu, Fe, Mn, Ni and even Co polyoxometalates, thus providing localised oxygen gas bursts to power nano-propulsion of composite materials.
Assuntos
Peróxido de Hidrogênio/química , Oxigênio/química , Compostos de Tungstênio/química , Soluções Tampão , Catalase/química , Catalase/metabolismo , Catálise , Concentração de Íons de Hidrogênio , Cinética , Metais/química , Oxigênio/metabolismo , Soluções/química , Espectrofotometria Infravermelho , Análise Espectral Raman , Termogravimetria , Compostos de Tungstênio/metabolismo , Água/químicaRESUMO
Hybrid fluoropolymeric membranes with 25% loading of the fluorous-tagged (RfN)4W10O32 effect the solvent-free photooxygenation of benzylic C-H bonds with up to 6100 TONs in 4 hours.