Separable Catalysts in One-Pot Syntheses for Greener Chemistry

A method that enables the separation between two different catalytic solids used in one-pot reactions is described. Such separation between the two catalytic solids can facilitate their reuse in other catalytic applications and make the synthesis cheap and greener. The method is based on doping one of the catalysts with magnetic nanoparticles, which can make it magnetically separable while the other solid can be separated by filtration. The magnetically separable catalytic solid is designed by a sol–gel process in which a palladium catalyst is encapsulated in a silica sol–gel-modified polyethylenimine composite in the presence of magnetic nanoparticles modified with ionic liquid groups. The other catalytic solid utilized in this study is a solid acid based on cross-linked polystyrene sulfonic acid and can be separated by simple filtration. The two catalytic solids are utilized in one-pot reactions of dehydration/hydrogenation of benzyl alcohols. After reaction, the palladium-based catalyst is separated by applying an external magnetic field and the solid acid is separated by filtration. The magnetically separable palladium-based catalyst is reused after utilization in a one-pot reaction to catalyze three different types of reactions: carbonylation of iodoarenes, Suzuki, and Heck coupling.