The action of onium salts and other modifiers on Pt/C, Pd/C, and Raney–Ni catalysts in the multiphase reduction system
Reactive and Functional Polymers Volume 54, Issues 1-3 , January 2003, Pages 95-101
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Abstract In the presence of a catalyst modifier (an onium salt, an amine, or a polyethylene glycol), in a biphasic aqueous–organic mixture, the reactivity of Pt/C, Pd/C, and Raney–Ni changes significantly. Hydrodehalogenation reactions of halo aromatics, reductions of functional groups on the aromatic ring, benzyl hydrogenolysis, can be conducted under mild conditions, and with interesting rates and regio-, chemo-, and stereoselectivities. The modifier coats the catalyst, and forms an interfacial film, wherein the reactions take place. This film partitions the catalyst at the aqueous–organic interface, and influences the outcome of the reactions by mediating substrate–catalyst interactions, and by providing a hydrogen reservoir in the vicinity of the active sites.