The reaction of butoxyl radicals with diborane has been shown by e.s.r. spectroscopy to yield t-butyl radicals. The rate constant for this process is given by k = 108.4 × 102.9/θ l mol -1 s-1 where θ = 2.303 RT in kcal mol-1. No intermediate 4-co-ordinate boron radical could be detected. Analogies are drawn with t-butoxyl-trialkyl phosphite reaction and with the oxidation of trialkylboranes by alkaline hydrogen peroxide and by amine oxides. t-Butyl radicals are not formed in detectable quantities in either the t-butoxyl-alkyldiborane or in the t-butoxyl-phosphine reactions.
Date de publication
Journal of the Chemical Society, Perkin Transactions 2, nº 4 (1973) : 420–424.