Pickering emulsion droplets hosting ionic liquid catalysts for continuous-flow cyanosilylation reaction†
Abstract
An IL-catalyzed cyanosilylation reaction is an important route for synthesis of many fine chemicals, but it is currently conducted in a batch manner. Herein, we have developed a novel method to “immobilize” IL catalysts for continuous-flow reaction based on the confinement of an IL catalyst within other IL-based Pickering emulsion droplets. The catalysis efficiency was significantly enhanced compared to the batch reaction, and it has no obvious decay after 100 h of continuous reaction. The excellent operational stability of the developed reaction system is attributed to the high stability of Pickering emulsion droplets along with the strong electrostatic interactions between the IL catalyst and the IL medium. It was interesting to find that the catalysis efficiency of [bmim]Cl within the [bmim]BF4 droplets is related to the droplet sizes. The insights into this relationship were gained based on the experimental observation and theoretical analysis. This study not only demonstrates a new method to immobilize IL catalysts but also provides an efficient platform to continuously process the reaction involving ILs as the reaction medium and catalysts.