Cross-Linked Imidazolium Salts as Scavengers for Palladium

Abstract Five imidazolium‐based materials have been synthesised and used for the first time as palladium scavengers. Radical reactions of suitable bis‐vinylimidazolium salts led to a series of insoluble materials through homo‐polymerisation, immobilisation with a 3‐mercaptopropyl‐modified silica gel or co‐polymerisation with ethylene glycol dimethylacrylate. These materials were screened as palladium scavengers with a set of palladium(0) and palladium(II) compounds in different solvents and at different starting amounts of palladium. In many cases, residual amounts of palladium were lower than 5 ppm, as requested for the manufacture of active pharmaceutical ingredients and fine chemicals. The application of one of these materials as a palladium scavenger in a Suzuki coupling reaction resulted in a 29‐fold abatement of the palladium content in the final product with respect to the control reaction.