A Kineic Study of the Reaction of tert-Butoxyl with Alkenes: Hydrogen Abstraction vs. Addition

Article abstract of DOI:10.1021/ja00383a018

Rate constants and Arrhenius parameters have been measured for the reactions of tert-butoxyl radicals with alkenes by using laser flash photolysis in benzene-di-tert-butyl peroxide (1:2 v/v) as solvent.With norbornene and norbornadiene, additions to the double bonds were the only modes of reaction, whereas with cyclopenene and cyclopentadiene, hydrogen abstraction was a competitive process.The measured activation energies were quite low; thus for norbornene, norbornadiene, and cyclopentene, E_a (kcal/mol) = 2.36 +/- 0.40, 1.56 +/- 0.55, and 2.35 +/- 0.22, respectively, while the corresponding A factors were log (A/(M^-1 s^-1)) = 7.76 +/- 0.31, 7.65 +/- 0.43, and 8.56 +/- 0.18, For comparison, hydrogen abstraction by tert-butoxyl at cyclopentane proceeds with E_a = 3.47 +/- 0.59 and log (A/(M^-1 s^-1)) = 8.47 +/- 0.45.