KINETICS OF MEDIATED REDUCTIONS BY CATHODICALLY GENERATED DIMETHYLPYRROLIDINIUM TIN COMPOSITES - THE CASE OF PHENYL BROMIDES

The initial electronation in the mediated reduction of phenyl bromides has been studied using a novel electroanalytical method. The mediator was dimethylpyrrolidinium-tin (DMP-Sn), generated in situ as a thin f ilm at a Sn cathode in DMF containing (DMP)BF4. Electron transfer from the electron-rich DMP-Sn composite to the phenyl bromide leads to oxi dative dissolution of the DMP-Sn to DMP+ and Sn(0). The rate of mediat ed reduction was experimentally determined from the dissolution rate o f the DMP-Sn film. The rate constants for 12 phenyl bromides studied s o far were evaluated through the application of the Langmuir-Hinshelwo od model for unimolecular surface reaction. The trend in rate constant s in relation to the properties of the PhBr molecules was discussed.