Heterogeneous catalysis in solution. Part VI. The effect of solids on the aquation of two halogenopenta-amminecobalt(III) ions

Abstract

The scattered literature references to the catalytic effects of solids such as charcoal and platinum on inorganic substitution reactions have been collected and reviewed. Kinetic studies are reported on the aquation at 25° of [Co(NH₃)₅Cl]²⁺ and [Co(NH₃)₅Br]²⁺; in dilute solution powdered platinum, palladium, and gold were very good catalysts, silver and mercury(I) halides and mercury(II) sulphide were good ones, while lead(II) sulphide, barium sulphate, boron nitride, and glass did not increase the rate. Silver, mercury, and charcoal caused rapid reduction to give cobalt(II). Attention is drawn to the danger of electrode catalysis in potentiometric and conductometric methods of following ionic substitution reactions.