Recently, a team led by Prof. Cao Zhi from the Institute of Coal Chemistry (ICC) of the Chinese Academy of Sciences (CAS), has made significant progress in the selective epoxidation of medium- and long- chain α-olefins. By analysis of the Mukaiyama epoxidation mechanism, they revealed significant differences in the kinetic diameters of key intermediates across different reaction pathways. The results have been published in Angew. Chem. Int. Ed. (DOI:10.1002/anie.202419900).

ABSTRACT: The efficient conversion of long-chain linear α-olefins (LAOs) into industrially useful epoxides is of pivotal importance. Mukaiyama epoxidation based on the use of molecular oxygen as the sole oxidant and aldehyde as the cosubstrate offers a promising route for LAOs epoxidation. However, challenges associated with epoxide forming selectivity and aldehyde coupling efficiency have long impeded the adoption of Mukaiyama epoxidation in large-scale applications. Herein, we show that confinement of key intermediates involved in the parallel epoxidation pathways within a Beta zeolite unlocks a selectivity of greater than 95 % towards the epoxides at the expense of minimal consumption of only 1.5 equivalents of the aldehyde, achieving an efficiency better than the state-of-the-art homogeneous and heterogeneous catalysts. Moreover, the incorporation of Sn sites into the Beta zeolite framework further facilitates the adsorption activation process of the aldehyde cosubstrate, thereby increasing the concentration of acylperoxy radicals and accelerating the kinetic process of the epoxidation step. Consequently, this work not only provides an efficient and green epoxidation route over zeolite catalysts with easily available O₂ as the oxidant, but also systematically reveals the fundamental understanding of the zeolite confinement effects on steering the reaction pathway, which benefits the further development of valorization of LAOs.