„Lebende Polymere” bei Ziegler-Katalysatoren extremer Produktivität

Sinn, Hansjörg; Kaminsky, Werner; Vollmer, Hans‐Jürgen; Woldt, Rüdiger

doi:10.1002/ange.19800920517

Cited by 256 publications

(95 citation statements)

References 9 publications

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“…Keywords: metal ± metal interactionś N ligands´nitrogen fixationń itrogen heterocycles´polymeriza-tions REVIEWS R. Kempe This was brought about by the discovery of their high alkene polymerization activities in combination with methylaluminoxane (MAO), [8,9] the stability of the ligand ± metal bond, and the frontier orbitals set up for the activation of small molecules. The renaissance of amidometal chemistry from the end of the 1980s to the middle of the 1990s is characterized mainly by the search for analogies between Cp and amido ligands.…”

Section: Highlights In the Renaissance Of Amidometal Chemistrymentioning

confidence: 99%

Highlights in the Renaissance of Amidometal Chemistry

Kempe¹

2000

Angewandte Chemie International Edition

271

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Turning a disadvantage to an advantage: The rather disappointing reactivity of the metal - nitrogen bond in comparison to the metal - carbon bond resulted in the neglect of amidometal chemistry after its heyday at the end of the 1960s and beginning of the 1970s. Today it is precisely this disadvantage which is being applied through the use of amido ligands to produce inert complex fragments with well-defined reaction centers. In this way the chemistry of the early transition metals has been markedly enriched, and interesting alternatives to the classically regarded cyclopentadienyl ligands are now available.

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Section: Highlights In the Renaissance Of Amidometal Chemistrymentioning

confidence: 99%

Highlights in the Renaissance of Amidometal Chemistry

Kempe¹

2000

Angewandte Chemie International Edition

271

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“…After informing Hansjörg Sinn, who had been Minister of Science and Research of the City State Hamburg since 1978, we decided to file a patent application covering these exciting results. 1 Later, we discovered that also the simple Cp 2 ZrCl 2 , which is much more stable than Cp 2 Zr(CH 3 ) 2 , is an active catalyst precursor in combination with MAO.…”

Section: The Discoverymentioning

confidence: 99%

“…[1][2][3] These catalyst systems have only one kind of active metal center (single site catalysts) and were the start-up for the introduction of a new family of transition metal complexes for olefin, diene, and styrene polymerization. Up to now, some 10,000 articles and more than 4000 patents have been published on the subject of polymerization with these single site catalysts.…”

Section: Introductionmentioning

confidence: 99%

The discovery of metallocene catalysts and their present state of the art

Kaminsky

2004

J. Polym. Sci. A Polym. Chem.

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361

221

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Metallocene and other transition metal complexes activated by methylaluminoxane are highly active catalysts for the polymerization of olefins, diolefins, and styrene, which was discovered at the University of Hamburg about 25 years ago. These catalysts allow the synthesis of polymers with a highly defined microstructure, tacticity, and stereoregularity, as well as new copolymers with superior properties such as film clarity, tensile strength, and lower extractables. A better understanding of the mechanism of olefin polymerization leads to findings of other new single site catalysts. The development of the metallocene/MAO-catalysts from their discovery to their present state of the art is presented. Keywords:metallocene catalysts; methylaluminoxane; olefin polymerization; zirconocene complexes; polyolefins; single site catalysis Dr. Kaminsky received his Ph.D. and degree in chemistry from Hamburg University, Germany in 1971 for investigating the side reactions of biscyclopentadienyl-zirconiumdichloride and triethylaluminum. He then served as lecturer and continued his research on the determination of zirconocene/aluminumalkyl-complexes and recycling of polymers by pyrolysis in a fluidized bed process. During that time he and Hansjörg Sinn discovered that the activity of metallocenes and other transition metals can be increased extremely by the addition of MAO as a cocatalyst. In 1979 he became full professor at the University of Hamburg for Technical and Macromolecular Chemistry and has served as director, dean, and president of German chemical society, Hamburg section. Dr. Kaminsky has received the following honors and rewards: elected to the

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“…Since the discovery of the powerful ability of methylaluminoxane (MAO) to convert metallocene derivatives into highly active olefin polymerization catalysts 1,2) , many spectroscopic studies have been done to determine the mechanism of active species formation and to identify the specific role of MAO and trimethylaluminium (TMA) 3,4) , always present in MAO solutions, during the metallocene activation process. By means of NMR studies, it has been shown that methylation of metallocene dichloride derivatives first occurs in presence of small quantities of MAO ([MAO]/[Zr] a 20).…”

Section: Introductionmentioning

confidence: 99%

Activation of iPr(CpFluo)ZrCl2 by methylaluminoxane, 4. UV/visible spectroscopic study in hydrocarbon and chlorinated media

Pédeutour

Coevoet

Cramail

et al. 1999

Macromol. Chem. Phys.

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, a hypsochromic shift of the initial iPr(CpFluo)ZrCl 2 absorption band, corresponding to the monomethylation of the metallocene dichloride, is observed. On the contrary, for higher Al/Zr ratios (with MAO uniquely), a bathochromic shift of the metallocene absorption band proceeding in two distinct steps is observed. These two steps are interpreted by the successive formation of associated (or complexed) and dissociated active zirconocenium species. The changes in the absorption spectra of iPr(CpFluo)ZrCl 2 / MAO are correlated with the initial activity observed for hex-1-ene polymerization in the various solvents examined. In the same way, the catalytic activity loss with polymerization time observed at elevated Al/Zr ratios (A1000) with this system is attributed to a reduction of active species concentration, as indicated by the intensity decrease of their UV/visible absorption band. This reveals the low stability of active species formed from iPr(CpFluo)ZrCl 2 compared to those from rac-Et(Ind) 2 ZrCl 2 .

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„Lebende Polymere” bei Ziegler-Katalysatoren extremer Produktivität

Cited by 256 publications

References 9 publications

Highlights in the Renaissance of Amidometal Chemistry

Highlights in the Renaissance of Amidometal Chemistry

The discovery of metallocene catalysts and their present state of the art

Activation of iPr(CpFluo)ZrCl2 by methylaluminoxane, 4. UV/visible spectroscopic study in hydrocarbon and chlorinated media

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