Rhodium-Catalyzed Hydrogenation in a CFMR

One of the success stories of transition metal catalysis is the rhodium-complex-catalyzed hydrogenation reaction. Asymmetric hydrogenation with a rhodium catalyst has been commercialized for the production of L-Dopa, and in 2001 the inventor, Knowles, together with Noyori and Sharpless, was awarded the Nobel Prize in chemistry. After the initial invention, (enantioselective) hydrogenation has been subject to intensive investigations (27). In general, hydrogenation reactions proceed 

Before the start of the continuous reaction, the substrate solution was saturated with hydrogen by stirring under 5 bar of H2 for 16h. Subsequently, a premixed solution of the ligand and the rhodium precursor [Rh(nbd)2](C104) was injected into the membrane autoclave, after which the substrate solution was pumped through the reactor. 

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