Polyethylene as a Cosolvent and Catalyst Support ... - ACS Publications

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Polyethylene as a Cosolvent and Catalyst Support in Ring-Opening Metathesis Polymerization Jakkrit Suriboot,† Christopher E. Hobbs,‡ William Guzman,† Hassan S. Bazzi,*,§ and David E. Bergbreiter*,† †

Department of Chemistry, Texas A&M University, College Station, Texas 77840, United States Department of Chemistry, Texas A&M University, Kingsville, Texas 78363-8202, United States § Department of Chemistry, Texas A&M University at Qatar, P.O. Box 23874, Doha, Qatar ‡

S Supporting Information *

ABSTRACT: Polyethylene oligomers (PEOlig) can be used as cosolvents and sometimes soluble catalyst supports in ringopening metathesis polymerization (ROMP) reactions. As a catalyst support, this polyolefin serves as an N-heterocyclic carbene ligand for a ROMP catalyst, making it soluble at 70 °C and insoluble at room temperature. As a cosolvent, unfunctionalized PE oligomers facilitate quantitative separation of PEOlig-bound Ru-catalyst residues from polymer products. In these cases, the insolubility of the unfunctionalized polyethylene (Polywax) and its entrapment of the PEOligsupported Ru residue in the product phase at room temperature afford ROMP products with Ru contamination lower than other procedures that use soluble catalysts. These separations require only physical processes to separate the product and catalyst residuesno additional solvents are necessary. Control experiments suggest that most (ca. 90%) of the Ru leaching that is seen results from Ru byproducts formed in the vinyl ether quenching step and not from the polymerization processes involving the PEOlig-supported Ru complex.

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leaching that was reported to be 2.8%.11 Another alternative approach for CM and RCM reactions is to design more and more active catalysts. This approach addresses this issue best since highly active catalysts with catalyst loadings of