Reactions of a Graded Set of Radicals with N-Bromosuccinimide; Two Transition States

Article abstract of DOI:10.1021/ja00389a059

The reactions of N-bromosuccinimide with a series of radicals have been studied.These reactions fall into two categories, the more reactive radicals producing ?-succinimidyl and the less reactive radicals producing ?-succinimidyl.The threshold for the changeover from one reaction domain to the other occurs with radicals less reactive than secondary alkyls.These results are interpreted with two transition states, an in-line transition state for the more reactive radicals and an out-of-plane transition state for the less reactive radicals. An upper limit of 18 kcal/mol is established for the enthalpy difference, H_S? - H_S?.Two new methods for generating S_? radicals are indicated.