Catalyzed Henry Reaction by Compartmentalized Copper-Pyrazolyl-Complex Modified Microgels

Compartmentalization of homogeneous catalysts enhances their catalytic performance and can even increase the selectivity. Microgels can serve as smart catalyst carrier systems offering the compartmentalization combined with good accessibility of the catalyst enabling the recyclability and re-usability. Yet, the incorporation of coordination complexes into microgels has not been studied systematically, lacking in detailed insight in their structure and catalytic performance. Herein, microgels are synthesized with controlled number and localization of copper(II)-pyrazolyl-complexes. The catalytic activity of microgels in the Henry reactions is examined showing significantly higher yields compared to pure copper(II)-pyrazolyl-complexes. Furthermore, the localization of the copper(II)-pyrazolyl-complexes in the microgel core resulted in higher product yields than for microgel catalysts with copper(II) complexes in the shell. Microgel catalysts are demonstrated with copper(II) complexes that can be used in numerous reaction cycles, allow re-loading of copper to recover catalytically active centers, and can be applicable in industrially-relevant catalytic processes.