The differences in current ratios serve as an indicator for the difference in catalytic activity of TEMPO towards the various substrates are shown in Figure . Isopropanol, a secondary alcohol, reacts much more slowly than the other substrates with primary alcohols. On the other hand, oxidation of acetaldehyde is kinetically facile, showing a current that is only slightly lower than that of ethanol, where oxidation of the alcohol is kinetically limiting despite the latter having the possibility of undergoing two catalytic cycles. Electronic effects are evident when comparing ethanol and trifluoroethanol; the highly electron-withdrawing trifluoro group should facilitate the removal of the alpha proton of the alcohol, which is reflected by a higher current ratio.