Inorganic supports advantages

Inorganic supports have been used less, but they have undeniable advantages, such as the relatively high oxidative stability of the support. A first attempt was made with salen complexes that are vinyl functionalized at both aromatic rings. By coupling in a thioether, catalyst 7f is obtained. For... 

Many heterogeneous catalysts have been reported in the past to be prepared by anchoring or grafting, processes whereby stable, covalent bonds are formed between an homogeneous transition metal complex and an inert polymer or inorganic support [1-4] The aim was to combine the potential versatility and selectivity of homogeneous catalysts with the practical advantages of a solid material [5]... 

Although the inorganic supports show many advantages such as temperature stabihty, solvent, and mechanical resistance, there are not many papers dealing with the use of these membranes for SLM construction, probably due to the same problems as for polymeric supports membrane stabihty and lifetime. 

Non-cross-linked polymers can be used in this way just as cross-linked polymers can. For example, we have used polyethylene supports with surface grafts to support Pd(0) catalysts [133,134]. In these cases, the polymer-immobilized catalyst is used in exactly the same way as an insoluble polymer-bound catalyst. Such supported catalysts do require that the insoluble polymer be swollen or permeable to substrates or that the catalysts be within a solvent-permeable, thin immobilized graft. While this approach can be useful, it takes no advantage of the polymer s solubility. It is an approach that conceptually is no different than that used with insoluble inorganic supports or with polymers that are by design insoluble by virtue of cross-linking, and is an approach to catalyst immobilization that is not further discussed since this review is focused on polymer-immobilized catalysts that are used under solution-state conditions. 

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