Sonogashira Coupling of Aryl Halides Catalyzed by Palladium on Charcoal, Zoltán Novák, András Szabó, József Répási, András Kotschy, J. Org. Chem. 2003, 68, 3327-3329. DOI: 10.1021/jo034149f | [Full Text Link] [Supp. Info Link]

With the proper choice of solvent, palladium on charcoal acts as an efficient catalyst in the Sonogashira cross-coupling reaction of aryl bromides. The catalytically active species in the process is probably palladium, which leaches into the solution but returns onto the surface of the charcoal at the end of the reaction.