The role of dormant sites in propene polymerization using methylalumoxane activated metallocene catalysts

Jüngling, Stephan; Mülhaupt, Rolf; Stehling, Udo; Brintzinger, Hans-Herbert; Fischer, David; Langhauser, Franz

The role of dormant sites in propene polymerization using methylalumoxane activated metallocene catalysts

Files

Juengling_240629.pdf(3.74 MB)

Date

1995

Authors

Jüngling, Stephan

Mülhaupt, Rolf

Stehling, Udo

Brintzinger, Hans-Herbert

Fischer, David

Langhauser, Franz

Publication type

Journal article

Published in

Macromolecular Symposia ; 97 (1995), 1. - pp. 205-216. - ISSN 1022-1360. - eISSN 1521-3900

Abstract

Propene polymerization of methylalumoxane (MAO) activated rac-Me₂Si(Benz[e]Indenyl)₂ZrCl₂ (BI) and rac-Me₂Si(2-Me-Benz[e]Indenyl)₂ZrCl₂ (MBI) was studied to investigate the influence of the ligand substitution pattern and the role of dormant sites. Poly(propene) end group composition as well as regio- and stereoirregularities were examined by means of ¹H- and ¹³C-NMR spectroscopy. Dormant sites, resulting from 2, 1-propene insertion, were reactivated either by β-hydrogen transfer to propene, yielding 2-butenyl end groups, or by 1, 2-insertion of propene, yielding regioirregularities. Propene polymerization in the presence of hydrogen gave n-butyl end groups and less regioirregularities as expected for hydrogenolysis of such dormant sites. Methyl substitution in 2-position of the benz[e]indenyl ligand suppressed β-hydrogen transfer to propene, and increased molecular weight with increasing propene concentration. Also, activation energy increased from 30 kJ/mol (BI/MAO) to 59 kJ/mol (MBI/MAO). For both catalysts activity depended on propene concentration. The order of reaction relative to propene was 1.7.

Subject (DDC)

540 Chemistry

Cite This

ISO 690

JÜNGLING, Stephan, Rolf MÜLHAUPT, Udo STEHLING, Hans-Herbert BRINTZINGER, David FISCHER, Franz LANGHAUSER, 1995. The role of dormant sites in propene polymerization using methylalumoxane activated metallocene catalysts. In: Macromolecular Symposia. 97(1), pp. 205-216. ISSN 1022-1360. eISSN 1521-3900. Available under: doi: 10.1002/masy.19950970121

BibTex

@article{Jungling1995dorma-24062,
  year={1995},
  doi={10.1002/masy.19950970121},
  title={The role of dormant sites in propene polymerization using methylalumoxane activated metallocene catalysts},
  number={1},
  volume={97},
  issn={1022-1360},
  journal={Macromolecular Symposia},
  pages={205--216},
  author={Jüngling, Stephan and Mülhaupt, Rolf and Stehling, Udo and Brintzinger, Hans-Herbert and Fischer, David and Langhauser, Franz}
}

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    <dcterms:abstract xml:lang="eng">Propene polymerization of methylalumoxane (MAO) activated rac-Me&lt;sub&gt;2&lt;/sub&gt;Si(Benz[e]Indenyl)&lt;sub&gt;2&lt;/sub&gt;ZrCl&lt;sub&gt;2&lt;/sub&gt; (BI) and rac-Me&lt;sub&gt;2&lt;/sub&gt;Si(2-Me-Benz[e]Indenyl)&lt;sub&gt;2&lt;/sub&gt;ZrCl&lt;sub&gt;2&lt;/sub&gt; (MBI) was studied to investigate the influence of the ligand substitution pattern and the role of dormant sites. Poly(propene) end group composition as well as regio- and stereoirregularities were examined by means of &lt;sup&gt;1&lt;/sup&gt;H- and &lt;sup&gt;13&lt;/sup&gt;C-NMR spectroscopy. Dormant sites, resulting from 2, 1-propene insertion, were reactivated either by β-hydrogen transfer to propene, yielding 2-butenyl end groups, or by 1, 2-insertion of propene, yielding regioirregularities. Propene polymerization in the presence of hydrogen gave n-butyl end groups and less regioirregularities as expected for hydrogenolysis of such dormant sites. Methyl substitution in 2-position of the benz[e]indenyl ligand suppressed β-hydrogen transfer to propene, and increased molecular weight with increasing propene concentration. Also, activation energy increased from 30 kJ/mol (BI/MAO) to 59 kJ/mol (MBI/MAO). For both catalysts activity depended on propene concentration. The order of reaction relative to propene was 1.7.</dcterms:abstract>
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