1987 Volume 35 Issue 4 Pages 1372-1377
The reactivity of phthalimide-N-oxyl radical (2), which is produced by an electrochemical one-electron oxidation of N-hydroxyphthalimide (1), was investigated. The self-decomposition of 2 obeyed second-order kinetics with respect to itself and the rate was little affected by changing the temperature or the concentration of dissolved oxygen, water or added base. In the reaction between 2 and benzhydrol or its α-deuterated derivative, the decay of the radical was first-order with respect to each component. The observed large deuterium isotope effect (kH/kD= 10.6 at 25 °C) is attributed to the rate-limiting hydrogen abstraction. Rate measurements were performed on the reaction with 24 other substrates which have one or more hydrogen atoms on a benzylic or allylic position or on a carbon adjacent to a hetero atom.
