Metal-Assisted Reactions. Part XXX. Control of Rates of Heterogeneously Catalyzed Transfer Hydrogenolysis through Changes in Solvent Composition

Adsorption isotherms in the liquid phase can be used to determine the relative strengths of adsorption of reactants and solvent at a catalyst surface. Such isotherms can then be used to indicate which type of solvent would be most suitable for a heterogeneously catalyzed reaction in the liquid-phase. Solubility in any chosen solvent is also important. As examples, rates of heterogeneously catalyzed liquid-phase transfer hydrogenolyzes of aryl tetrazolyl ethers (1) have been shown to be highly dependent on both the nature of the solvent and on the solution concentrations of the reactants. The rate of reaction can be varied from zero to a maximum and then back to zero simply by adjusting the solubility of the reductant through changes in the proportion of water in a mixed-solvent system.