Patterns of activity in the benzene–deuterium exchange reaction and the hydrogenation of benzene catalysed by evaporated metal films

Abstract

The hydrogenation and exchange reactions of benzene with molecular deuterium catalysed by evaporated films of twelve transition elements (Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Ta, W, Re and Ir) have been examined in the region of room temperature. Copper, silver and gold were found to be inactive. Concentrations of surface sites were measured by deuterium chemisorption at 77 or 273 K and were used to calculate specific activities. The patterns of activity for exchange and for hydrogenation show a remarkable parallelism across the first and third transition series; this pattern is mirrored by changes in the electrical conductivities of the bulk metals, and this implies a relation with the electronic structures of the metals. An inverse relation is found between the specific rates and the calculated densities of states at the Fermi level.

New information concerning the mechanisms of reaction is reported.