Metathesis under Biphasic Conditions Using Monolithic-Supported Ionic Liquids

聚合物单片支架可以通过开环复分解聚合（ROMP）或电子束（EB）引发自由基聚合来制备。由此产生的多孔整体结构将作为离子液体（ILs）的支撑材料，在离子液体（ILs）中溶解一系列具有离子部分的新型复分解催化剂。复分解反应应在双相条件下进行，使用与IL不混溶的第二有机相。为此，将合成具有悬垂离子基团的新型持久性，IL可溶性Schrock和grubb - hoveda型催化剂。单体应使用基于季铵、咪唑和磷盐以及2-丙氧基苯乙烯醚的离子单体进行原位表面功能化。在romp衍生单体的情况下，这是通过使用相应的生2-烯或环烯衍生物来完成的。对于eb -触发自由基聚合衍生的单体，含有季铵、咪唑和磷盐的丙烯酸酯以及2-丙氧基苯乙烯醚将通过合成后的eb -触发自由基聚合进行表面接枝。或者，应采用使用上述生-2-烯或环烯衍生物的基于romp的方案。然后，根据用于表面接枝的类似结构基序（即用于相应的季铵化N基和p基单体），用适量的离子液体（il）处理由此制备的表面功能化单体。需要特别注意的是相容性问题，这主要与接枝分子和il的性质、接枝密度以及接枝聚合物的聚合程度有关，接枝聚合物分别以季铵盐、咪唑盐和磷盐为基础。在所有情况下，最终的功能化单体应以微孔和中孔为特征。除了接枝聚合物和离子液体之间的离子相互作用外，这些孔允许通过毛细力将离子液体（ILs）保留在表面。此外，必须有足够的μm范围内的互连孔，以保证快速通过。从接枝密度、接枝聚合物的链长、功能单体和IL的性质以及IL的最佳层厚等方面进行优化，从而在提供最佳催化性能的同时实现最小的浸出。最终目标是实现新型离子复分解催化剂，并将其固定在整体负载的ILs中，并将其用于双相条件下的连续复分解反应，包括闭环复分解（RCM）、开环交叉复分解（ROC）、交叉复分解和烯炔交叉复分解反应。由此创建的固定化体系将进一步深入了解Schrock-和grubb - hoveyda型催化剂在ILs内的复分解反应中的反应活性。更重要的是，这里要开发的负载型催化剂，要有助于解决载体再生充电、产品金属污染、催化剂寿命等问题。

Polymeric monolithic supports shall be prepared either via ring-opening metathesis polymerization (ROMP) or via electron beam (EB) triggered free radical polymerization. The resulting porous monolithic structures shall serve as support materials for Ionic liquids (ILs) in which a series of novel metathesis catalysts bearing ionic moieties shall be dissolved. Metathesis reactions shall be run under biphasic conditions using a second organic phase immiscible with the IL. For these purposes, novel persistent, IL-soluble Schrock and Grubbs-Hoveyda-type catalysts with pendant ionic groups are to be synthesized. The monoliths shall be subject to in situ surface functionalization using ionic monomers based on quaternary ammonium, imidazolium and phosphonium salts as well as with 2-propoxystyryl ethers. In the case of ROMP-derived monoliths, this is to be accomplished by the use of the corresponding norborn-2-ene or cyclooctene derivatives. In the case of EB-triggered free radical polymerization-derived monoliths, acrylates containing quaternary ammonium, imidazolium and phosphonium salts as well as 2-propoxystyryl ethers are to be surface-grafted via post-synthesis, EB-triggered free radical polymerization. Alternatively, a ROMP-based protocol using the above-mentioned norborn-2-ene or cyclooctene derivatives shall be applied. The thus prepared surface-functionalized monoliths shall then be treated with appropriate amounts of ionic liquids (ILs) based on a similar structural motif as used for surface grafting (i.e. for the corresponding quaternaized N- and P-based monomers). Special care shall be devoted to compatibility issues, which are mainly related to both the nature of the grafted molecules and the ILs and to the grafting density as well as of the degree of polymerization of the graft polymers based on the quaternary ammonium, imidazolium and phosphonium salts, respectively. In all cases, the final functionalized monoliths shall be characterized by micro- and mesopores. Apart from ionic interactions between the graft polymers and the ILs, these pores allow for retaining the ionic liquids (ILs) at the surface by capillary forces. In addition, sufficient interconnected pores in the μm-range shall be present and guarantee for a fast flow-through. An optimization in terms of grafting density, chain length of the graft polymers, nature of the functional monomer and IL as well as optimum layer thickness of the IL shall be carried out, thus offering optimum catalytic performance while resulting in a minimum leaching. The ultimate goal is the realization of novel ionic metathesis catalysts, their immobilization within monolith-supported ILs, and the use of the thus prepared supported catalysts in continuous metathesis reactions including ring-closing metathesis (RCM), ring-opening cross metathesis (ROC), cross-metathesis and ene-yne cross metathesis reactions under biphasic conditions. The thus created immobilized systems shall provide further insight into the reactivity of both Schrock- and Grubbs-Hoveyda-type catalysts in metathesis reactions within ILs. Even more important, the supported catalysts to be developed here shall help to solve the problems of support-regeneration and recharging, metal contamination of products and catalyst longevity.