Abstract
The catalytic synthesis of linear α-olefins from ethylene is a technologically highly important reaction. A synthesis concept allowing the formation of selective products and various linear α-olefin product distributions with one catalyst system is highly desirable. Here, we describe a trimetallic catalyst system (Y–Al–Ni) consisting of a rare earth metal polymerization catalyst which can mediate coordinative chain transfer to triethylaluminum combined with a simultaneously operating nickel β-hydride elimination/transfer catalyst. This nickel catalyst displaces the grown alkyl chains forming linear α-olefins and recycles the aluminum-based chain transfer agent. With one catalyst system, we can synthesize product spectra ranging from selective 1-butene formation to α-olefin distributions centered at 850 gmol−1 with a low polydispersity. The key to this highly flexible linear α-olefin synthesis is the easy tuning of the rates of the Y and Ni catalysis independently of each other. The reaction is substoichiometric or formally catalytic regarding the chain transfer agent.
Highlights
The catalytic synthesis of linear α-olefins from ethylene is a technologically highly important reaction
A fundamental problem associated with Coordinative chain-transfer polymerization (CCTP) is the inverse first-order dependence of the rate of the chain growth from the chain-transfer agent (CTA) concentration, which restricts the number of chains that can be grown efficiently by a catalyst molecule, called catalyst economy[9]
We expected that by choosing the right combination of CCTP catalyst, displacement catalyst and CTA, a broadly tunable linear α-olefins (LAOs) synthesis process would become feasible which permits the synthesis of different olefin product distributions and selective LAO formation with one catalyst system
Summary
The catalytic synthesis of linear α-olefins from ethylene is a technologically highly important reaction. We introduced the corresponding concept, the combination of CCTP and alkyl chain displacement via β-H elimination/transfer for α-olefin synthesis[12]. A displacement catalyst, here Ni-based, recycles the TEA via β-hydride elimination/transfer forming LAOs that match the length of the alkyl chains formed.
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