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Published on: October 18, 2019
Selective dimerisation of alpha-olefins using tungsten-based initiators.
Martin J Hanton1, Louisa Daubney, Tomas Lebl
1Sasol Technology UK, St Andrews Laboratory, Purdie Building, North Haugh, St Andrews, Fife, UK KY16 9ST. martin.hanton@eu.sasol.com
Dalton Transactions (Cambridge, England : 2003)
|May 27, 2010
Summary
This study details a selective alpha-olefin dimerization using a tungsten hexachloride catalyst. The process favors branched dimers and follows a Cossee-type mechanism, minimizing heavier oligomers.
Area of Science:
- Organometallic Chemistry
- Polymerization Catalysis
- Olefin Chemistry
Background:
- Selective oligomerization of alpha-olefins is crucial for producing valuable chemical intermediates.
- Tungsten-based catalysts offer potential for controlled olefin transformations.
Purpose of the Study:
- To investigate the selective dimerization of alpha-olefins (1-pentene to 1-nonene) using an in situ-generated tungsten catalyst.
- To explore the influence of various reaction parameters on catalyst performance and product selectivity.
- To elucidate the reaction mechanism.
Main Methods:
- In situ catalyst generation from tungsten hexachloride, aniline, triethylamine, and alkylaluminium halide.
- Systematic variation of reagents, stoichiometry, activator, solvent, and substrate.
- Kinetic studies and co-dimerization experiments (C2H4/C2D4) to probe the mechanism.
Main Results:
- High selectivity towards dimerization, with minimal formation of heavier oligomers.
- Preference for branched dimer products.
- Identification of trace dienes and alkanes.
- Kinetic analysis indicated a second-order dependence on the substrate.
- Co-dimerization experiment confirmed a Cossee-type mechanism with full isotopic scrambling.
Conclusions:
- The developed tungsten-based catalyst system enables highly selective alpha-olefin dimerization.
- The reaction proceeds via a Cossee-type mechanism, accounting for observed product distributions.
- The study provides insights into catalyst design for controlled olefin oligomerization.
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