Efficient Epoxidation Catalyst Predicted

A class of organometallic compounds, discovered via computation, has the potential to catalyze key industrial reactions in a way that uses less energy and generates fewer by-products than current methods. Propylene oxide, which is used to make polyurethanes, polyester resins, and other compounds, ranks as one of the world’s top chemical products. Worldwide annual production lies in the 10 billion-lb range. Some industrial methods for making propylene oxide generate chlorinated by-products. Others are complicated by the need for coreactants to make coproducts to improve process economics. A computational study suggests those issues can be avoided. Thomas A. Manz and Bo Yang of New Mexico State University calculate that a novel solution-phase bidentate zirconium complex can efficiently mediate propene epoxidation directly with molecular oxygen without the need for coreactants. They predict that the reaction will proceed by way of a peroxo-η³-ozone intermediate (shown) with an activation energy of just 28 kcal/mol, the lowest value reported for any direct propene epoxidation catalyst to date (RSC Adv. 2014, DOI: 10.1039/c4ra03729d).