Tandem ROMP/Hydrogenation Approach to Hydroxy-Telechelic Linear Polyethylene

Hydroxy-telechelic polyalkenamers have long been synthe-sized using ring-opening metathesis polymerization (ROMP) in the presence of an acyclic olefin chain-transfer agent (CTA); however, this route typically requires protected diols in the CTA due to the challenge of alcohol-mediated degradation of ruthenium metathesis catalysts that can not only deactivate the catalysts, but also compromise the CTA. We demonstrate the synthesis and implementation of a new hydroxyl-containing CTA in which extended methylene spacers isolate the olefin and alcohol moieties to mitigate decomposition pathways. This CTA enabled the direct ROMP synthesis of hydroxy-telechelic polycyclooctene with controlled chain lengths dictated by the initial ratio of monomer to CTA. The elimination of protection/deprotection steps resulted in improved atom economy. Subsequent hydrogenation of the backbone olefins was performed by a one-pot, catalytic approach employing the ruthenium complex used for the initial ROMP. The resultant approach is a streamlined, atom-economic, and low-waste route to hydroxy-telechelic linear polyethylene that uses a green solvent, succeeds with miniscule quantities of catalyst (0.005 mol %), and requires no additional purification steps.

Automated summary

In this study, a new hydroxyl-containing chain transfer agent (CTA) was developed, which allowed for the direct synthesis of hydroxy-telechelic polyalkenamers and subsequent hydrogenation using a streamlined catalytic approach. This method offers high atom economy, low waste generation, uses a green solvent, requires minimal catalyst quantity, and does not require additional purification steps.