Heterogeneous catalysis in solution. Part 13.—Kinetics of racemisation in two immiscible phases with rapid exchange across the interface, illustrated by the racemisation of (+)589-tris(ethylenediamine)-cobalt(III) catalysed by a carbon black

Abstract

The kinetic equations have been solved for optical racemisations taking place in two immiscible phases with rapid exchange between them, thus allowing such systems to be investigated by sampling one phase only. Heterogeneous catalysis can be treated by regarding the surface layer as one of the phases. The new theory has been applied to the previously reported¹ rates for carbon-black catalysis of the racemisation of (+)₅₈₉-tris(ethylenediamine)cobalt(III) tri-iodide in aqueous solution. The two-phase approach confirms the main kinetic conclusions drawn earlier, and removes certain anomalies; in particular, the surface rate constant is now independent of the mass of catalyst.