“Transition metals, and in particular palladium, have been of importance for the development of reactions for the formation of carbon-carbon bonds.” - The Royal Swedish Academy Of Sciences, Palladium-Catalyzed Cross Couplings in Organic Synthesis
Many reactions involving the formation of carbon-carbon bonds, for instance the Wacker process, or the Heck, Sonogashira or Suzuki cross-coupling reactions, utilize transition metals as catalysts. With a heterogeneous catalyst, the separation is straightforward (especially when using a rotating bed reactor), but in the case of homogeneous catalysis, the metal remains in the product after the reaction. The catalyst contaminates the product, and also remains a value worth recovering. Both are valid reasons why recovery of the metal is desirable.
Palladium catalysts can be removed from a liquid using scavenger resins, which are conveniently deployed in a rotating bed reactor. In this application note, we remove from an organic solvent Pd(OAc)₂, or palladium acetate, which is a commonly used catalyst. Initially the liquid has a dark red colour, indicating the presence of the catalyst, and after the scavenging it becomes colourless, signifying that the metal has been scavenged onto the resin.
