Recently, the Green and Bionic Catalysis Research Team of the University of Chemistry and Chemistry has made breakthrough progress in multi-step series catalytic chiral chemicals.
The chemical industry is the pillar industry of the national economy, with the annual output value of fine chemicals reaching more than 4 trillion yuan.In China and the world, there are many reaction steps, long route, high energy consumption, low atomic economy, and more waste emissions, so it is urgent to develop green and efficient synthesis technology.The multi-step cascade (parallel) continuous flow catalytic reaction in one pot is an important way to realize the green and efficient chemical reaction process.A multi-step cascade (parallel) catalysis often involves a variety of heterogeneous catalysts, multiphase catalysts and biocatalysts of completely different properties. Among them, homogeneous catalysts and biocatalysts usually require specific liquid reaction media.
The Green and Bionic Catalysis team has long devoted itself to the study of multi-step cascade catalysis on micro-nanometer interface or micro-nanometer space, and put forward the concept of Pickering milk droplet fixed bed catalysis (J). Am. Chem. Soc. 2016, 138, 10173–10183；J. Am. Chem. Soc. 2017, 139, 17387?17396）。In the present work, the concept is extended to the continuous flow system of Pickering droplets and solid porous microspheres, that is, homogeneous catalyst or enzyme-limited region in Pickering droplets.The key to this strategy is that Pickering droplets and solid microspheres can exist stably for a long time under continuous flow conditions, and the reaction intermediates can be "directed" between Pickering droplets and solid microspheres.The stability of the co-fill system depends on the hydrophilic surface of the solid microspheres, which can easily enter the inside of the Pickering droplets and cause milk breakage.The EEE value of chiral cyanide and chiral ester was maintained at 99% and the conversion rate was maintained at 90%. The catalytic efficiency of chiral cyanide and chiral ester was increased to 7–77 times.
This study breaks away from the traditional concept of fixed-bed catalysis and expands the types of fixed-bed catalysis. It provides a new system for efficient chain reaction of homogeneous, multiphase catalyst and enzyme.