Mechanistic investigations of the ethylene tetramerisation reaction
Mechanistic investigations of the ethylene tetramerisation reaction
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DOI：
10.1021/ja052327b
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发表时间：
2005-08-03
影响因子：
15
通讯作者：
Morgan, DH
中科院分区：
文献类型：
--
作者：
Overett, MJ;Blann, K;Morgan, DH
乙烯选择性四聚制1-辛烯是近年来研究的热点。在本研究中，这种新的转换的各种机制方面进行了调查。铬催化乙烯四聚反应中异常高的1-辛烯选择性是由操作中独特的扩展金属环机理引起的。1-辛烯和高级1-烯烃都是通过进一步将乙烯插入金属环庚烷中间体中形成的，而1-己烯是通过从该物质中消除而形成的，如在其他报道的三聚反应中。氘标记研究、1-烯烃产物的摩尔分布分析和次级共低聚反应产物的鉴定支持了这一点。此外，两个C-6环状产物，亚甲基环戊烷和甲基环戊烷，的形成进行了讨论，并提出了一个反式异构化的机制来解释现有的数据。
The unprecedented selective tetramerisation of ethylene to 1-octene was recently reported. In the present study various mechanistic aspects of this novel transformation were investigated. The unusually high 1-octene selectivity in chromium-catalyzed ethylene tetramerisation reactions is caused by the unique extended metallacyclic mechanism in operation. Both 1-octene and higher 1-alkenes are formed by further ethylene insertion into a metallacycloheptane intermediate, whereas 1-hexene is formed by elimination from this species as in other reported trimerisation reactions. This is supported by deuterium labeling studies, analysis of the molar distribution of 1-alkene products, and identification of secondary co-oligomerization reaction products. In addition, the formation of two C-6 cyclic products, methylenecyclopentane and methylcyclopentane, is discussed, and a bimetallic disproportionation mechanism to account for the available data is proposed.