Oxidation of Higher Alcohols and Aldehydes

When introduced into the solution at potentials of the double layer region, alcohols and aldehydes containing more than one carbon atom cause [4, 39, 84, 85] the potential to become less positive. After passing through a minimum, the potential remains unchanged or becomes more positive. In contrast to methanol, the potential may move into the positive direction again. If the substances are added close to (7 = 0, gas bubble formation is observed. The evolution of gases proceeds actively at first and slows down with time. It is very small when a steady-state potential 

The behavior of formaldehyde differs in some aspects from that of higher aldehydes. After adding formaldehyde, potentials below 0.1 V are established as for methanol. It was proposed [39] that the hydrogenation of formaldehyde proceeds in sulfuric acid solution only until methanol is formed. Chemisorbed species similar to those formed in the presence of methanol or formic acid are produced at open circuit [58] and by anodic oxidation [40] of formaldehyde. 

Evolution of gases is not observed during the steady-state oxidation of alcohols and alhydes in acid and alkaline electrolytes. The i — U curve 1 in Fig. 66 was measured [39] on platinized platinum during an anodic sweep with 5mV/sec in 0.5M C2H5OH- -0.05M H2SO4. It represents nearly the steady-state i—U curve. Curve 2 is the Tafel line resulting 

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