Poly -supported catalysts

Salts of neodecanoic acid have been used in the preparation of supported catalysts, such as silver neodecanoate for the preparation of ethylene oxide catalysts (119), and the nickel soap in the preparation of a hydrogenation catalyst (120). Metal neodecanoates, such as magnesium, lead, calcium, and zinc, are used to improve the adherence of plasticized poly(vinyl butyral) sheet to safety glass in car windshields (121). Platinum complexes using neodecanoic acid have been studied for antitumor activity (122). Neodecanoic acid and its esters are used in cosmetics as emoUients, emulsifiers, and solubilizers (77,123,124). Zinc or copper salts of neoacids are used as preservatives for wood (125). 

Ultimately, the ligand itself can be polymerized and used as both ligand and support in one [110]. Pu and coworkers have prepared the rigid chiral poly-BI-NAP ligand below (Fig. 42.17) and used it after treatment with Rh and Ru in asymmetric hydrogenations. The supported catalysts showed similar activities and enantioselectivities to their homogeneous analogues, with the benefit of... 

In 1993 Bergbreiter prepared two soluble polymer-supported phosphines that exhibited an inverse temperature-dependent solubility in water [52]. Although PEG-supported phosphine undergoes a phase-separation from water at 95-100 °C, the PEO-poly(propylene oxide)-PEO supported catalyst was superior as it is soluble at low temperatures and phase-separates at a more practical 40-50 °C. Treatment of a diphenylphosphinoethyl-terminated PEO-PPO-PEO triblock copolymer... 

Covalently attaching molecular catalysts to supports is a method that can minimize catalyst leaching. In 1998, a PS-supported titanocene was prepared by Barrett and de Miguel, which displayed 41 g-PE mmol-Ti h of activity. Soga and co-workers reported a series of poly(siloxane)-supported metallocene catalysts. These supported catalysts combined with MAO were found to have high activity for the (co)polymerization of ethylene, propylene, and ethylene/l-octene, though the reaction products typically displayed broad molecular weight distributions. ... 

Rare earth metal triflates are recognized as a very efficient Lewis acid catalysts of several reactions including the aldol reaction, the Michael reaction, allylation, the Diels-Alder reaction, the Friedel-Crafts reaction, and glycosylation [110]. A polymer-sup-ported scandium catalyst has been developed and used for quinoline library synthesis (Sch. 8) [111], because lanthanide triflates were known to be effective in the synthesis of quinolines from A-arylimines [112,113]. This catalyst (103) was readily prepared from poly(acrylonitrile) 100 by chemical modification. A variety of combinations of aldehydes, amines, and olefins are possible in this reaction. Use of the polymer-supported catalyst has several advantages in quinoline library construction. 

Kinoshita has also shown that ORR data for supported catalysts in hot, concentrated H3PO4 (180 °C, 97-98% acid) reported in three different studies were also fit by this model. Since the physical basis for the crystallite size effect in sulfuric acid is anion adsorption, it would be a considerable reach to suggest that the same physical basis applies to this size effect, i.e., structure-sensitive anion adsorption. There are, nonetheless, indications that this is the case. Anion adsorption in dilute phosphoric [43] has a very similar structure sensitivity as sulfate adsorption, i.e., strongest adsorption on the (111) face, and on poly-Pt anion adsorption and/or neutral molecule adsorption in dilute phosphoric has a strongly inhibiting effect on the kinetics of the ORR [43]. Sattler and Ross [16] report a similar crystallite size dependence of the ORR on supported Pt in dilute phosphoric acid at ambient temperature as that found in hot, concentrated acid with the same catalysts. But it is unclear whether similar adsorption chemistry would exist in the extreme conditions of hot, concentrated phosphoric acid. 

Preparation and Characterization of Poly(styrene—divinylbenzene)-Supported Catalysts... 

Insoluble polymer-supported catalysts ion exchange resins, poly-DMAP, poly-vinyl pyridine, and others... 

The most common polymer supports used for chiral catalyst immobilization are polystyrene-based crosslinked polymers, although poly(ethylene glycol) (PEG) represents an alternative choice of support. In fact, soluble PEG-supported catalysts show relatively high reactivities (in certain asymmetric reactions) [le] which can on occasion be used in aqueous media [le]. Methacrylates, polyethylene fibers, polymeric monoliths and polynorbornenes have been also utilized as efficient polymer supports for the heterogenization of a variety of homogeneous asymmetric catalysts. 

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