Simplified Preparation of ppm Pd-Containing Nanoparticles as Catalysts for Chemistry in Water

A protocol has been developed that not only simplifies the preparation of nanoparticles (NPs) containing ppm levels of ligated palladium that affect heterogeneous catalysis but also ensures that they afford products of cross-couplings reproducibly due to the freshly prepared nature of each reagent. Four different types of couplings are studied: Suzuki-Miyaura, Sonogashira, Mizoroki-Heck, and Negishi reactions, all performed under mild aqueous micellar conditions. The simplified process relies on the initial formation of stable, storable Pd- and ligand-free NPs, to which is then added the appropriate amount of Pd(OAc)₂ and ligand-matched to the desired type of coupling, in water.