Hydroformylation

Discovered in 1938, hydroformylation is the most important example of the industrial application of homogeneous catalysis. Production is now well beyond 10 million metric tons annually. Propene-based products still account for two-thirds of this volume. Highly selective processes using ligand-modified rhodium catalysts have been developed and are state of the art. Technology and markets for the products have matured, so there is little room for improvement. With the industry placing more emphasis on speciality chemicals, researchers are interested in applying this versatile reaction to more sophisticated chemistry and are focusing on modifying rhodium with ligands to tune the properties. Over the last 20 years, a myriad of ligands have been developed. In-situ NMR and IR under reaction conditions and molecular modeling are modern tools for gaining insight into the intricate mechanism, but the reaction is still far from being understood. From the viewpoint of engineers, the crucial problem of homogeneous catalysis, recycling the generally expensive catalysts, has not been satisfactorily solved. As a consequence, old but robust high pressure processes are witnessing a revival. After 60 years, hydroformylation is just beginning to be a general tool for chemists, and new frontiers and challenges have to be met.