Electrochemically induced nucleophilic substitution of perfluoroalkyl halides. An example of a dissociative electron-transfer-induced chemical reaction
摘要:
Nucleophilic substitution of perfluoroalkyl halides can be induced electrochemically. The reaction mechanism is a slightly modified version of the classical S(RN)1 mechanism in which the reaction is triggered by dissociative electron transfer, not involving the intermediacy of the anion radical of the substrate. Direct electrochemical induction is possible in principle with the iodides but not with the bromides because the reduction potentials of the substrate and of the perfluoroalkyl radical are too close in the latter case. This impossibility can be overcome by using as inductor an electrochemically generated outer-sphere electron donor. Thiolates react at the sulfur atom whereas phenoxide as well as imidazolate ions react at ring carbons rather than at the negatively charged heteroatom.