Reaction between aminoalkyl radicals and akyl halides: Dehalogenation by electron transfer?

Aminoalkyl radicals, such as Et(2)NC center dot HCH(3), have low oxidation potentials and are therefore powerful reducing agents. We have found that Et(2)NC center dot HCH(3) reacts with CCl(4) and CBr(4) in di-tert-butyl peroxide with bimolecular rate constants (measured by LFP) close, or equal, to the diffusion-controlled limit. For the less reactive halide, CH(2)Br(2), the reaction rate is increased substantially by the addition of acetonitrile as a co-solvent. It is tentatively concluded that these reactions occur by electron-transfer from the aminoalkyl to the organohalide with formation of the iminium ion, Et(2)N(+)=CHCH(3) (NMR detection), halide ion and a halomethyl radical, e.g., (center dot)CCl(3) and (center dot)CHCl(2) (ESR, spin-trapping detection). (C) 2011 Elsevier B. V. All rights reserved.