Mechanistic investigations of the ethylene tetramerisation reaction.
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 C6 cyclic products, methylenecyclopentane and methylcyclopentane, is discussed, and a bimetallic disproportionation mechanism to account for the available data is proposed.
Overett
Matthew J
MJ
Sasol Technology (Pty) Ltd, R&D Division, 1 Klasie Havenga Road, Sasolburg 1947, South Africa. Matthew.Overett@Sasol.com
Blann
Kevin
K
Bollmann
Annette
A
Dixon
John T
JT
Haasbroek
Daleen
D
Killian
Esna
E
Maumela
Hulisani
H
McGuinness
David S
DS
Morgan
David H
DH