Catalytic hydrogenation of the 2,2-diphenyl-1-picryl-hydrazyl free radical in presence of a rhodium catalyst

Abstract

1. The free radical 2,2-diphenyl-1-picrylhydrazyl undergoes stagewise hydrogenation over a rhodium catalyst. At first hydrogen adds at the free valence; this reaction is of zero order. 2. The low rate of hydrogenation of 2,2-diphenyl-1-picrylhydrazyl is to be explained by the high value of its conjugation energy, which is due to the delocalization of the free electron.