Ran Pan, Qiu Aoqian, Liu Tianshu, Wang Fangyuan, Tian Bailin, Xiang Beiyao, Li Jun, Lv Yang, Ding Mengning
Key Laboratory of Mesoscopic Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, Jiangsu, China.
Nat Commun. 2024 Oct 15;15(1):8877. doi: 10.1038/s41467-024-53049-z.
Production of epoxides via selective oxidation of olefins affords a fundamental source of key intermediates for the industrial manufacture of diverse chemical stocks and materials. Current oxidation strategy generally works under harsh conditions including high temperature, high pressure, and/or request for potentially hazardous oxidants, leading to substantial challenges in sustainability and energy efficiency. To this end, direct electrocatalytic epoxidation poses as a promising solution to these issues, yet their industrial applications are limited by the low selectivity, low yield, and poor stability of the electrocatalysts. Here we report a universal electrochemical epoxidation approach via a kinetically confined surface radical pathway. High epoxidation efficiency can be achieved under mild working conditions (e.g., >99% selectivity, >80% yield and >80% Faraday efficiency for cyclohexene-to-cyclohexene oxide conversion), which can be extended to broad scope of olefin substrates. The catalytic performance originated from a surface bimolecular (L-H) reaction mechanism involving formation and surface confinement of bromine radicals due to kinetic restriction, which effectively activates inert C=C bonds while avoiding the homogenous radical side reactions. With the use of renewable energy and water as green oxygen source, successful implementation of this approach will pave the way for more sustainable chemical production and manufacturing.
通过烯烃的选择性氧化生产环氧化合物为多种化学原料和材料的工业制造提供了关键中间体的基本来源。当前的氧化策略通常在高温、高压和/或需要潜在危险氧化剂等苛刻条件下进行，这给可持续性和能源效率带来了巨大挑战。为此，直接电催化环氧化是解决这些问题的一个有前景的方案，但其工业应用受到电催化剂选择性低、产率低和稳定性差的限制。在此，我们报道了一种通过动力学受限表面自由基途径的通用电化学环氧化方法。在温和的工作条件下（例如，环己烯转化为环氧环己烷的选择性>99%、产率>80%和法拉第效率>80%）可以实现高环氧化效率，并且该方法可扩展到广泛的烯烃底物。催化性能源于一种表面双分子（L-H）反应机制，由于动力学限制，该机制涉及溴自由基的形成和表面限制，它能有效激活惰性碳-碳双键，同时避免均相自由基副反应。利用可再生能源和水作为绿色氧源，该方法的成功实施将为更可持续的化学生产和制造铺平道路。
