title: Reverse-flow adsorption for process-integrated recycling of homogeneous transition-metal catalysts.
abstract: Supramolecular strategies, based on hydrogen bonds and ionic interactions, were investigated as tools for the recovery and recycling of homogeneous transition-metal catalysts by using reverse-flow adsorption (RFA) technology. The association (in solution) and adsorption (on support) of new functionalized host materials and phosphine guest ligands, functionalized with the complementary binding motifs, were fine-tuned for the application of these materials in a RFA reactor. The RFA technology for process-integrated recycling of homogeneous catalysts using these tailor-made phosphine ligands and silica-supported host materials resulted in a stable, semicontinuous catalytic system. Rhodium-catalyzed asymmetric hydrogenation of methyl acetamidoacrylate and asymmetric hydrosilylation of acetophenone were studied as test reactions. Depending on the catalytic process the metal complex could be recycled several times without significant loss in conversion.
authors.affiliation: Supramolecular & Homogeneous Catalysis Group van 't Hoff Institute for Molecular Sciences, University of Amsterdam, Nieuwe Achtergracht 166, 1018 WV Amsterdam, The Netherlands.
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Marras
authors.forename: Piet W N M
authors.initials: PW
authors.lastname: van Leeuwen
authors.forename: Joost N H
authors.initials: JN
authors.lastname: Reek