title: New catalysts for carboxylation of propylene glycol to propylene carbonate via high-throughput screening.
abstract: High throughput methodologies screened 81 different metal salts and metal salt combinations as catalysts for the carboxylation of propylene glycol to propylene carbonate, as compared to a 5 mol% Zn(OAc)2/p-chlorobenzene sulfonic acid benchmark catalyst. The reactions were run with added acetonitrile (MeCN) as a chemical water trap. Two new catalysts were thereby discovered, zinc trifluoromethanesulfonate (Zn(OTf)2) and zinc p-toluenesulfonate. The optimal reaction parameters for the former catalyst were screened. Zn(OTf)2 gave an overall propylene carbonate yield of greater than 50% in 24 h, twice as large as the previous best literature yield with MeCN as a water trap, with 69% selectivity and 75% conversion of propylene glycol at 145 °C and 50 bar CO2 pressure.
authors.affiliation: University of York, Department of Chemistry, Green Chemistry Center of Excellence, York YO10 5DD, North Yorkshire, England, UK.
authors.forename: José A
authors.initials: JA
authors.lastname: Castro-Osma
authors.forename: James W
authors.initials: JW
authors.lastname: Comerford
authors.forename: Richard H
authors.initials: RH
authors.lastname: Heyn
authors.forename: Michael
authors.initials: M
authors.lastname: North
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Tangstad