Studies by electron spin resonance of the reactions of alkylperoxy radicals. Part 1.—Absolute rate constants for the termination reactions of alkylperoxy radicals

Authors:
  • JBJ. E. Bennett
    J. E. Bennett
  • DBD. M. Brown
    D. M. Brown
  • BMB. Mile
    B. Mile
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Abstract
Alkylperoxy radicals, produced by the photolysis of solutions of di-t-butyl peroxide in oxygen-saturated alkanes, have been detected by electron spin resonance spectroscopy. Tertiary alkylperoxy radicals terminate with second-order kinetics, and absolute termination rate constants have been measured over a range of temperatures (–60 to +20°C). The process has an unusually high activation energy (ca. 8 kcal mol–1) for a reaction involving two radicals. Secondary alkylperoxy radicals decay more rapidly by a reaction which has a smaller activation energy (ca. 2 kcal mol–1). The decay of primary radicals is so rapid that the radical concentration is too small to be detected. A new method is described for the measurement of cross-termination rate constants.