STANDARD OXIDATION POTENTIALS OF METHYLBENZENES IN ACETONITRILE

Combined use of ultramicroelectrodes and of an ultrafast potentiostat equipped with on-line ohmic drop compensation has allowed the determination of standard oxidation potentials for a series of methlybenzenes (E(Bz-CH3)0) = 1.58 (hexamethylbenzene), 1.69 (pentamethylbenzene), 1.77 V (1,2,3,4-tetramethylbenzene) vs. a saturated calomel electrode). These values are used to evaluate absolute rate constants for the deprotonation of the corresponding cation radicals by a series of pyridine bases. These latter values compare satisfactorily with those determined previously by time-resolved spectroscopy.