Determination of rate constants for trifluoromethyl radical addition to various alkenes via a practical method
1Organisch-Chemisches Institut, Westfäliscihe Wilhelms-Universität Münster, Corrensstraße 40, 48149 Münster, Germany. studer@uni-muenster.de.
Abstract:
A simple and practical method for the determination of rate constants for trifluoromethyl radical addition to various alkenes by applying competition kinetics is introduced. In the kinetic experiments the trifluoromethyl radicals are generated in situ from a commercially available hypervalent-iodine-CF3 reagent (Togni-reagent) by SET-reduction with TEMPONa in the presence of TEMPO and a π-acceptor. From the relative ratio of TEMPOCF3 and CF3-addition product formed, which is readily determined by (19)F-NMR spectroscopy, rate constants for trifluoromethyl radical addition to the π-acceptor can be calculated. The practical method is also applicable to measure rate constants for the addition of other perfluoroalkyl radicals to alkenes as documented for CF3CF2-radical addition reactions.
Related Concept Videos
Radical Reactivity: Concentration Effects
Radical Substitution: Halogenation of Alkanes and Alkyl Substituents
In the initiation step of the reaction, the chlorine molecule undergoes homolytic cleavage in the presence of light or heat, forming two highly reactive chlorine radicals. Propagation occurs in two...
Radical Anti-Markovnikov Addition to Alkenes: Mechanism
The mechanism starts with chain initiation, which involves two steps. In the first chain initiation step, a weak peroxide bond is homolytically cleaved upon mild heating to form two alkoxy radicals. In the second initiation step, a hydrogen atom is abstracted by the alkoxy...
Radical Substitution: Allylic Chlorination
Radical Reactivity: Nucleophilic Radicals
Radical Halogenation: Thermodynamics


