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首页> 外文期刊>Chemistry: A European journal >Re-based heterogeneous catalysts for olefin metathesis prepared by surface organometallic chemistry: reactivity and selectivity
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Re-based heterogeneous catalysts for olefin metathesis prepared by surface organometallic chemistry: reactivity and selectivity

机译：通过表面有机金属化学制备的用于烯烃复分解的Re-based非均相催化剂：反应性和选择性

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摘要

Herein we describe the catalytic activity of 1, a well-defined Re alkylidene complex supported silica, in the reaction of olefin metathsis. This system is highly active for terminal and internal olefins with initial rates up to 0.7 mol per mol Re per s. It also catalyses the self-metathesis of methyl oleate (MO) without the need of co-catalysts. The turnover numbers can reach up to 900 for MO, which is unprecedented for a heterogeneous Re-based catalyst. Moreover the use of silica as a support can bring major advantages, such as the possibility to use branched olefins like isotubene, which are usually incompactible with alumina-based supports; therefore, the formation of isoamylene from the cross-metathesis of propene and isobutene can be performed. All these results are in sharp contrast to what has been found for other silica-or alumina-supported rhenium oxide systems, which are either completely inactive (silica system) or typically need co-catalysts when functionalised olefins are used. Finally the initiation step corresponds to a cross-metathesis reaction to give a 3:1 mixture of 3,3-dimethylbutene and trans-4,4-dimethylpent-2-ene, and make this catalyst the first generation of well-defined Re-based heterogeneous catalysts.
机译：本文中，我们描述了1（一种定义明确的Re亚烷基络合物负载的二氧化硅）在烯烃复分解反应中的催化活性。该系统对末端和内部烯烃具有很高的活性，初始速率最高为每摩尔Re s 0.7 mol。它也可以催化油酸甲酯（MO）的自我复分解反应，而无需助催化剂。 MO的周转率可以达到900，这对于异质Re基催化剂来说是前所未有的。此外，使用二氧化硅作为载体可以带来主要的优势，例如可以使用支链烯烃，如异丁烯，通常与氧化铝基载体不相容。因此，可以由丙烯和异丁烯的交叉复分解形成异戊烯。所有这些结果与其他二氧化硅或氧化铝负载的氧化rh体系形成的鲜明对比，后者完全不活泼（二氧化硅体系），或者在使用官能化烯烃时通常需要助催化剂。最后，引发步骤对应于交叉复分解反应，得到3,3-二甲基丁烯与反式4,4-二甲基戊-2-烯的3：1混合物，并使该催化剂成为第一代定义明确的Re-基非均相催化剂。

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