Venturello catalyst

Venturello catalyst 197 Hoveyda 243 hydrazine 469 hydrazone, unsaturated 46 hydroboration 48 hydrogen shift 55 hydrogenation... 

In the case of supported Venturello catalyst of [(C6H13)4N]3[P04 W0(02)2 4], epoxidation of cyclooctene was performed by using 30% aqueous H202 without organic solvents ... 

A particularly interesting system for the epoxidation of propylene to propylene oxide, working under pseudo-heterogeneous conditions, was reported by Zuwei and coworkers [61]. The catalyst, which was based on the Venturello anion combined with long-chained alkylpyridinium cations, showed unique solubility properties. I11 the presence of hydrogen peroxide the catalyst was fully soluble in the solvent, a 4 3 mixture of toluene and tributyl phosphate, but when no more oxidant was left, the tungsten catalyst precipitated and could simply be removed from the... 

The first examples of an electrostatie attachment of POMs on solid supports are dated to the mid 1980. Baba et al. reported immobilization of heteropolyacids on the anion-exchange resin Amberlist-15 [68]. Later on, this type of the support was successfully used by Jacob s group to immobilize the Venturello complex P04[W0(02)2]4, well known as highly selective homogeneous catalyst for H202-based epoxidation of alkenes... 

Hydrogen peroxide may be efficiently employed for the epoxidation of unfunctionalized aikenes in the presence of polyoxo complexes of tungsten and molybdenum . Venturello and coworkers first developed a phosphotungstate catalyst , with particular emphasis on the tetrakis(diperoxotungsto)phosphate anion P04[W(0)(02)2]4 , 37 , that in conjunction with H2O2 and a lipophilic tetra-alkylammonium salt Q+X as phase transfer... 

POMs can he immobilized onto anion-exchange resins and surface-modified metal oxides with quaternary ammonium cation- or amino-functional groups via anion-exchange. Jacobs and coworkers tethered Venturello s catalyst [P04(W0(02)2)4]3-on a commercially available nitrate-form resin with alkylammonium cations and have carried out the epoxidation of allylic alcohols and terpenes with this supported catalyst [166, 167]. The regio- and diastereoselectivity of the parent homogeneous catalysts were preserved in the supported catalyst. For bulky alkenes, the reactivity of the POM catalyst was superior to that of Ti- 3 zeolite with a large pore size. The catalytic activity of the recycled catalyst was maintained completely after several cycles. 

Angeletti E, Canepa C, Martinetti G, Venturello P (1989) Amino groups immobilized on silica gel An efficient and reusable heterogeneous catalyst for the knoevenagel condensation. J Chem Soc Perkin Trans 1 105... 

Venturello type catalyst in a pseudo-heterogeneous catalytic fashion, in... 

The group of Ishi described a similar system to that of Venturello consisting of H3[PWi204o] in combination with H2O2 and a PTR [147,148]. However, it has been demonstrated that the two catalyst systems involve the oxoperoxo anion [PO4 WO(O2)2 4] [149,150] derived from polyoxometallates. 

C. Venturello, R. D Alolslo, Quaternary ammonium tetrakis(diperoxotungsto)phosphates(3-) as a new class of catalysts for efficient alkene epoxidation with hydrogen peroxide, J. Org. Chem. 53 (1988) 1553. 

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