Phenylacetate, electrolysis

Carbocations can also be generated during the electrolysis, and they give rise to alcohols and alkenes. The carbocations are presumably formed by an oxidation of the radical at the electrode before it reacts or diffuses into solution. For example, an investigation of the electrolysis of phenylacetic acid in methanol has led to the identification of benzyl methyl ether (30%), toluene (1%), benzaldehyde dimethylacetal (1%), methyl phenylacetate (6%), and benzyl alcohol (5%), in addition to the coupling product bibenzyl (26%). ... 

It may be that ultrasonic enhancement of mass transport sweeps the intermediate radicals that have escaped the electrode back to the electrode surface where they are further oxidized, although this would depend upon radical lifetimes. Direct enhancement of the second electron transfer to give the cation while species remain in first contact with the electrode would be complicated by the decarboxylation step after the first electron transfer, and also by an observation of weak electrochemiluminescence (ECL) from the electrolysis cell in phenylacetate electrooxidation (see Section 5.2) [215]. This is enhanced by ultrasound, as are a number of other ECL systems. This suggests that at least a proportion of the reaction pathway involves benzyl radicals which escape the electrode, although the sonoelectrochemilumines-cence reaction conditions of low carboxylate concentration, low current density, and presence of electrolyte salt are different to those for the preparative electrolyses. 

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