全氟烷基芳基酮与苯基溴化镁电子转移反应的EPR研究

EPR Studies on Electron Transfer Reactions Between Perfluoroalkyl Phenyl Ketones and Phenyl Magnesium Bromide

有关酮与格氏试剂反应的自由基历程早有报道,运用EPR手段已经获得了自由基中间体存在的证据,但一直认为极性历程是该反应的主要途径.文献指出,二芳基酮的格氏反应是按单电子转移引发的自由基历程进行的,龚跃法等曾以2,5-二甲氧基苯基烷基酮(ArCOR)与叔丁基格氏试剂作用,发现亦由SET引发的自由基反应.本文运用ESR手段研究了全氟烷基芳基酮与苯基溴化镁的反应历程,证实了中间体阴离子自由基的存在。

EPR observations of the ketyl radical intermediates in the reactions of nine perfluo-roalkyl substituted-phenyl ketones with phenyl magnesium bromide in ether and THF reveal the electron-transfer nature of the process.The effects of the substituenta and solvent polarity on the reactivity are discussed.