α,ω-Diene Generation from Ethylene and Butadiene by Copolymer Upcycling

Abstract

Linear α-olefins are accessed efficiently from ethylene in the Shell higher olefin process (SHOP), an industrial process practiced on a million-ton scale that generates a statistical mixture of C₄-C₃₀ products. An analogous general process for the preparation of a range of α,ω-dienes is lacking. We herein report a two-step method that generates industrially relevant α,ω-dienes. In the first step, ethylene and butadiene are copolymerized to generate copolymers with a variable butadiene content. A titanium bisphenoxide bisthiolate catalyst activated with methylaluminoxane (MAO) was selected for this step due to the high selectivity for 1,4-butadiene incorporation. Ethenolysis of the copolymers results in a distribution of α,ω-dienes in the C₁₀-C₂₀ range. Depending on the conditions, linear trienes are also generated. The reported protocol provides a strategy for copolymer upcycling to value-added olefin products.

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