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Kolbe electrolysis of mixtures of n‐butanoic with n‐hexanoic acid and propanoic with n‐hexanoic acid have been performed in aqueous solution at a smooth platinum anode. Typically, hexane production by the oxidation of butanoic acid, or butane production from propanoic acid, in aqueous solution is not observed to exceed a few percent. In the current work, significant increases of these products were observed. In addition, a substantial fraction of the remaining C3 or C4 acids reacted were converted to mixed alkane dimers with hexanoic acid. These results are interpreted by a model in which n‐hexanoic acid and its various oxidation products form a lipophilic layer at the anode surface which provides an environment where further oxidation to carbonium ions is disfavored. This model has been suggested previously to explain pressure effects on Kolbe electrolysis (1). This observation supports the feasibility of producing mixed linear alkanes for use as fuels and chemicals from mixed organic acids which may be produced by anaerobic fermentation of organic matter.

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Experiments have been run which demonstrate that electrochemical oxidation ofn-alkanoic acids (in the range of C4-C6) in aqueous solution at a smooth platinum anode gives higher yields of alkane dimer product when run at elevated pressures than an equivalent experiment at atmospheric pressure. This phenomenon has been observed over awide range of reaction conditions. A plausible explanation for this result is that under high pressure conditions, olefin accumulates at the anode surface which helps to prevent the water, required to stabilize intermediates in the formation of competitive products, from reaching the electrode surface.