Pappuru Sreenath, Shpasser Dina, Carmieli Raanan, Shekhter Pini, Jentoft Friederike C, Gazit Oz M
Faculty of Chemical Engineering and the Grand Technion Energy Program, Technion-Israel Institute of Technology, Haifa 320003, Israel.
Department of Chemical Research Support, Weizmann Institute of Science, Rehovot 76100, Israel.
ACS Omega. 2022 Jul 5;7(28):24656-24661. doi: 10.1021/acsomega.2c02488. eCollection 2022 Jul 19.
The conversion of CO and epoxides to cyclic carbonates over a silica-supported di-iron(III) complex having a reduced Robson macrocycle ligand system is shown to proceed at 1 atm and 80 °C, exclusively producing the -cyclohexene carbonate from cyclohexene oxide. We examine the effect of immobilization configuration to show that the complex grafted in a semirigid configuration catalytically outperforms the rigid, flexible configurations and even the homogeneous counterparts. Using the semirigid catalyst, we are able to obtain a TON of up to 800 and a TOF of up to 37 h under 1 atm CO. The catalyst is shown to be recyclable with only minor leaching and no change to product selectivity. We further examine a range of epoxides with varying electron-withdrawing/donating properties. This work highlights the benefit arising from the constraining effect of a solid surface, akin to the role of hydrogen bonds in enzyme catalysts, and the importance of correctly balancing it.
在具有还原罗布森大环配体体系的二氧化硅负载二价铁（III）配合物上，一氧化碳和环氧化物转化为环状碳酸酯的反应在1个大气压和80℃下进行，由环氧环己烷仅生成碳酸 - 环己烯酯。我们研究了固定化构型的影响，结果表明，以半刚性构型接枝的配合物在催化性能上优于刚性、柔性构型甚至均相类似物。使用半刚性催化剂，在1个大气压的一氧化碳条件下，我们能够获得高达800的总转化数和高达37 h⁻¹的转化频率。该催化剂显示出可回收利用，仅有少量浸出，且产物选择性无变化。我们进一步研究了一系列具有不同吸电子/供电子性质的环氧化物。这项工作突出了固体表面的约束效应所带来的益处，类似于氢键在酶催化剂中的作用，以及正确平衡这种效应的重要性。
