Palladium is used in the following sectors of homogeneous catalysis:
Carbonylations are conversions with carbon monoxide under formation of aldehydes, ketones, or carboxylic acids by inserting a C=O group.
For the production of fine or pharmaceutical chemicals and specialties, some functional groups can be carbonylated by using various phosphorus-containing palladium compounds, e.g. for the conversion of alkenes and alkynes into acrylates. The active species are Pd(0)-phosphane fragments: Therefore, there is a need of catalyst precursors of Pd(0) and Pd(II) respectively that contain phosphanes themselves or that are applied in situ along with phosphanes.
The palladium-based "Suzuki Coupling" reaction represents a method of linking an aryl halide ArX with an organoboron acid. Thus, in the presence of CO substituted aryl ketones Ar(CO)R can be synthesized.
Coupling reactions serve to link organic molecules or parts within a molecule mostly by forming carbon-carbon bonds ("C-C Coupling"). Such reactions are popular in the industries of pharmaceuticals, agrochemicals, fine chemicals, and specialties.
Similar to carbonylations these processes are based on Pd(0) and Pd(II) catalysts or their precursors. A large number of similar coupling reactions (according to "Suzuki", "Matsuda", "Stille", etc.) are based on this palladium chemistry. Important products are e.g. biphenyls for agrochemicals or liquid crystals.
Also some oxidations can be homogeneously carried out on a large scale with precious metals. The best-known case is the "Hoechst-Wacker" process: The synthesis of acetaldehyde from ethene and oxygen in the presence of the catalyst system Pd/Cu (in aqueous, chloride-containing solutions). Thus, other products can be obtained by varying the solvent, the starting material, or the process parameters, e.g. acetic anhydride and butane-2-one respectively from but-1-ene, or allyl acetate from propene.
In the presence of oxidizing agents, the oxidation of alcohols is feasible by using palladium – and more often ruthenium.
Hydrosilations represent reactions to build up higher-molecular organosilicon compounds (silanes, siloxanes), and thus they are the basis of manufacturing silicones. Today silicone products are found all over the dental, automotive, building, polymer, or paper industries. Platinum is the most effective metal for this homogeneously catalytic reaction. In special cases rhodium as well as palladium may serve as hydrosilation catalysts.
Moreover, Heraeus manufactures new catalysts on a commercial scale and in strict confidence according to customers’ specifications.