Palladium Nanoparticles on Graphite Oxide as Catalyst for Suzuki-Miyaura, Mizoroki-Heck, and Sonogashira Reactions

Pd2+-Exchanged graphite oxide (GO) serves as a precatalyst for the formation of Pd-nanoparticles which are then deposited on the highly functionalized carbonaceous support. This versatile, air-stable, and ligand-free system was applied successfully to Suzuki-Miyaura couplings of some aryl chlorides and to the Mizoroki-Heck as well as the Sonogashira reaction showing relatively high activities and good selectivities. Like with other ligand-free supported systems, the reaction proceeded dominantly by a homogeneous mechanism, but attack of an aryl iodide to Pd-nanoparticles can be excluded as substantial contribution to the entire catalytic process. Beside its straightforward preparation and its stability in air, the system combines the advantages of both homogeneous and heterogeneous catalysis.