Continuous hydrogenation reactions in a tube reactor packed with Pd/C.

Continuous flow of the substrate solution and hydrogen gas through a tube reactor packed with Pd/C catalyst brings about a highly reactive and efficient hydrogenation system, which converts 4-cyanobenzaldehyde to the benzyl alcohol derivatives at 25 degrees C, and at 90 degrees C, the cyano group becomes reduced to give the corresponding amine and toluene derivatives within 2 min.