Heterogeneous catalytic hydrogenation reactions in continuous-flow reactors.

Microreactor technology and continuous flow processing in general are key features in making organic synthesis both more economical and environmentally friendly. Heterogeneous catalytic hydrogenation reactions under continuous flow conditions offer significant benefits compared to batch processes which are related to the unique gas-liquid-solid triphasic reaction conditions present in these transformations. In this review article recent developments in continuous flow heterogeneous catalytic hydrogenation reactions using molecular hydrogen are summarized. Available flow hydrogenation techniques, reactors, commonly used catalysts and examples of synthetic applications with an emphasis on laboratory-scale flow hydrogenation reactions are presented.