Vol. 7S under those experimental conditions where the fraction cleavage does not exceed 33%. The validity of this mechanism, as a partial explanation of the facts, has not yet been determined.Detailed Chemistry.-The kinetic analysis presented above does not permit a complete determination of the mechanism for the cleavage reaction. However, equations 4a-4e suggest that the cleavage results from the oxidation of the carbinol to a real or potential oxygen cation, which then undergoes cleavage. The kinetic study must be supplemented by stereochemical and other investigations before a detailed mechanism can be presented.Isotope Effects.-Although the set of reactions in equations 4a-4e explains the kinetics and the cleavage yields satisfactorily, and accounts for the effect of deuterium substitution on the reaction rate, it nevertheless is true that the isotope effect is somewhat larger than usual.19 Deuterium substitution decreases the rate of the oxidation of isopropyl alcohol by a factor of 8 at 0°in 86.5% acetic acid4e and by a factor of 6.9 in water20 at 25°. Large and unusual isotope effects have, however, occasionally been reported.21 The usual kn/k-o ratio is the result of the zero-point energy difference which arises when a C-H vibration, in the reacting molecule, is converted, in the transition state, to transla-(19) W.
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