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

Linear a-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 C-4-C-30 products. An analogous general process for the preparation of a range of a,?-dienes is lacking. We herein report a two-step method that generates industrially relevant a,?-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 a,?-dienes in the C-10-C-20 range. Depending on the conditions, linear trienes are also generated. The reported protocol provides a strategy for copolymer upcycling to value-added olefin products.

Automated summary

Linear a-olefins are efficiently prepared from ethylene in the Shell higher olefin process (SHOP), while a general process for the preparation of a range of α,β-dienes is lacking. Here, we report a two-step method that generates industrially relevant α,β-dienes. We demonstrate the generation of a distribution of α,β-dienes in the C10-C20 range through the ethenolysis of copolymers obtained by the copolymerization of ethylene and butadiene.