α‐olefin oligomers with narrow molar mass distributions from zirconocene/methylaluminoxane catalysts — An examination of the structure‐reactivity relationship

Abstract

A series of tert-butyl substituted zirconocene/methylaluminoxane catalysts illustrates the potential for the tailoring of olefin oligomers with extremely narrow molar mass distributions, which are explained on the basis of a chain-length dependent propagation rate.Comparative oligomerization experiments provide a means to estimate the relative rates for chain propagation versus chain transfer as well as a correlation with the metallocene structure.

Analyses of Propene and 1-Hexene Oligomers from Zirconocene/MAO Catalysts - Mechanistic Implications by NMR, SEC, and MALDI-TOF MS

“…The known zirconocene dichlorides were prepared according to literature procedures, or slight modifications thereof: (C 5 HMe 4 )(C 5 H 5 )ZrCl 2 (2), [38] (C 5 HMe 4 ) 2 ZrCl 2 (3), [38,39] (C 4 Me 4 P)(C 5 H 5 )ZrCl 2 (4), [38] (C 4 Me 4 P) 2 ZrCl 2 (5), [38,40] (C 5 Me 5 )(C 5 H 5 )ZrCl 2 (6), [38,41] (C 5 Me 5 ) 2 ZrCl 2 (7), [38,42] (C 5 H 4 t Bu)(C 5 H 5 )ZrCl 2 (8), [43] (C 5 H 4 t Bu) 2 ZrCl 2 (9), [44] (C 5 H 3 -1,3-t Bu 2 )(C 5 H 5 )ZrCl 2 (10), [37] (C 5 H 2 -1,2,4-t Bu 3 )(C 5 H 5 )ZrCl 2 (11), [45] (C 5 H 3 -1,3-t Bu 2 ) 2 ZrCl 2 (12). [46] All complexes were purified by sublimation and the purity was checked by elemental analysis, NMR, and mass spectrometry.…”

“…A dispersity of Q a 2 can be explained by a chain-length dependent insertion rate. [12] It is evident that a combination of methods is necessary for the elucidation of chain-termination mechanism and of the oligomer parameters. The methods 1 H, SEC (GPC) and MALDI-TOF MS each give different necessary pieces of information.…”

“…[1 -3] We investigated the oligomerization of propene and 1-hexene of 12 different systematically alkylsubstituted zirconocenes and phospholyl-zirconocenes (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12) in combination with MAO. [4] The use of olefin oligomers as intermediates for specialty chemicals drives the interest in the catalytic oligomerization.…”

“…Oligomer characterization was carried out by 1 In the beginning of metallocene catalysis the finding of low molar-mass products from propene polymerizations with zirconocene catalysts was generally regarded as unfortunate. [8 -11] Following in part the communication of our earlier results, [12] it is now more and more recognized that metallocene catalysts can be used effectively for the directed oligomerization of a-olefins. [7, 13 -19] The chaintermination reaction gives oligomers with mostly doublebond end groups, predominantly of the vinylidene type (13).…”

Preparation method of superactive Ziegler–Natta catalysts to produce ultra-high molecular weight amorphous poly(1-octene), poly(1-decene), and their copolymers

“…The polymers produced by single-center metallocene catalysts have low molecular weight with narrow molecular weight distribution [15][16][17][18][19]. However, the productivity of a metallocene catalyst is over a period of 60 min and after this time their activity deteriorates significantly, whereas by Ziegler-Natta catalysts, ultra-high molecular weight polyolefins can be produced [6,7,20].…”