The action of onium salts and other modifiers on Pt/C, Pd/C, and Raney–Ni catalysts in the multiphase reduction system

✍ Scribed by Pietro Tundo; Alvise Perosa

• Publisher: Elsevier Science
• Year: 2003
• Tongue: English
• Weight: 428 KB
• Volume: 54
• Category: Article
• ISSN: 1381-5148
• DOI: 10.1016/s1381-5148(02)00185-2

✦ Synopsis

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.