Kinetics of hydrogen isotope-exchange reactions. Part 25.—pH-Dependence of aromatic exchange initiated by photolysis of aqueous potassium iodide solutions

Abstract

The aromatic tritium exchange reaction brought about by the action of light in iodide solutions containing tracer tritium and dissolved benzene is shown to depend on the acidity of the solution, falling off to a lower value at high pH. This behaviour is consistent with the existence of two exchange routes, one initiated by hydrogen(tritium) atoms and one by solvated electrons. The latter route assumes prominence only when insufficient hydrogen ions are present to compete effectively with benzene for solvated electrons. The effect of added nitrous oxide and nitrate ions is quantitatively consistent with the action of these species as electron scavengers.