An Unexpected Pressure Effect in the Catalytic Hydrogenolysis of a Complex Benzyl Amine

The selective hydrogenolysis of a complex benzylamine containing a pyridone ring and aryl fluorides was investigated. The aim of the research was to find a catalyst and reaction conditions under which the complete hydrogenolysis of the benzylamine could be accomplished with no aryl fluoride cleavage nor pyridone hydrogenation observed. This objective was accomplished by use of a specific 10 % Pd/C catalyst in a THF/EtOH solvent at 40 °C. It was found that as the H 2 pressure decreased the amount of debenzylated amine increased because of the decrease in pyridone hydrogenation. Unexpectedly, though, the rate of hydrogenolysis also increased with decreasing H 2 pressure. A rationale for this observation is presented.