Nonaqueous Electrocatalytic Oxidation of the Alkylaromatic Ethylbenzene by a Surface Bound Ruv(O) Catalyst

The catalyst [Ru(Mebimpy)(4,4'-((HO)(2)OPCH2)(2)bpy(OH2)](2+), where Mebimpy is 2,6-bis(1-methylbenzimidazol-2-yl)pyridine and 4,4'-((HO)(2)OPCH2)(2)bpy is 4,4'-bismethlylenephosphonato-2,2'-bipyridine, attached to nanocrystalline Sn(IV)-doped In2O3 (nanoITO) electrodes (nanoITOIRu(II)-OH22+) has been utilized for the electrocatalytic oxidation of the alkylaromatics ethylbenzene, toluene, and cumene in propylene carbonate/water mixtures. Oxidative activation of the surface site to nanoITO vertical bar Ru-v(O)(3+) is followed by hydrocarbon oxidation at the surface with a rate constant of 2.5 +/- 0.2 M-1 s(-1) (I = 0.1 M LiClO4, T = 23 +/- 2 degrees C) for the oxidation of ethylbenzene. Electrocatalytic oxidation of ethylbenzene to acetophenone occurs with a faradic efficiency of 95%. H/D kinetic isotope effects determined for oxidation of ethylbenzene point to a mechanism involving oxygen atom insertion into a C H bond of ethylbenzene followed by further 2e(-)/2H(+) oxidation to acetophenone.