Hydrogenation of a 4-benzylpyridine derivative over supported precious metal catalysts

The heterogeneous catalytic hydrogenation of 4-(4-fluorobenzyl)pyridine resulted in 4-(4-fluorobenzyl)piperidine, an important and valuable pharmaceutical intermediate. The effects of solvents, temperature, catalytic metals and amount of catalyst on the conversion and the rate of the hydrogenation were investigated. Among the precious metal catalysts applied, the best result was obtained by using a rhodium on carbon catalyst. Palladium or platinum on carbon also showed high activities. This hydrogenation is a key step in an industrially feasible synthesis developed recently.