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Hirvi, Janne T., Bochmann, Manfred 
ORCID: https://orcid.org/0000-0001-7736-5428, Severn, John R. and Linnolahti, Mikko
(2014)
Formation of octameric methylaluminoxanes by hydrolysis of trimethylaluminum and the mechanisms of catalyst activation in single-site alpha-olefin polymerization catalysis.
ChemPhysChem, 15 (13).
2732–2742.
ISSN 1439-4235
Abstract
Hydrolysis of trimethylaluminum (TMA) leads to the formation of methylaluminoxanes (MAO) of general formula (MeAlO)n(AlMe3)m. The thermodynamically favored pathway of MAO formation is followed up to n = 8, showing the major impact of associated TMA on the structural characteristics of the MAOs. The MAOs bind up to five TMA molecules, thereby inducing transition from cages into rings and sheets. Zirconocene catalyst activation studies using model MAO co-cat alysts show the decisive role of the associated TMA in forming the catalytically active sites. Catalyst activation can take place either by Lewis-acidic abstraction of an alkyl or halide ligand from the precata- lyst or by reaction of the precatalyst with an MAO-derived AlMe2+ cation. Thermodynamics suggest that activation through AlMe2+ transfer is the dominant mechanism because sites that are able to release AlMe2+ are more abundant than Lewis-acidic sites. The model catalyst system is demonstrated to polymerise ethene.
| Item Type: | Article |
|---|---|
| Faculty \ School: | Faculty of Science > School of Chemistry |
| UEA Research Groups: | Faculty of Science > Research Groups > Synthetic Chemistry (former - to 2017) Faculty of Science > Research Groups > Chemistry of Light and Energy Faculty of Science > Research Groups > Chemistry of Materials and Catalysis |
| Depositing User: | Pure Connector |
| Date Deposited: | 23 Dec 2015 15:00 |
| Last Modified: | 22 Oct 2022 00:33 |
| URI: | https://ueaeprints.uea.ac.uk/id/eprint/55884 |
| DOI: | 10.1002/cphc.201402298 |
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