Electrolysis of Aromatic Compounds

In the aliphatic series the carboxylic acids furnish the principal material of electrolysis. This is due to the reactive-ness of their anions, which readily split off carbonic acid, thus affording manifold syntheses. In the aromatic series, however, the nitro-compounds are the more interesting, on account- of their easy rcducibility and the importance of their reduction products. The facts which give to electrochemical reduction pre-eminence over oxidation have already been explained in 

Single oxidation processes have, however, also become important. Besides the oxidability of easily oxidizahle substances, for instance aniline, or easily oxidizable groups like methyl, the peculiar reaction which seems to occur very frequently in the electrical oxidation in sulphuric acid, and which consists of the entrance of oxygen into the benzene nucleus, must be emphasized. Hydrocarbons, phenols, quin-ones, and azo-compounds seem to behave alike in this respect. 

Electrolytic substitutions furnish a further general point of view. 

Although the substitution processes afforded by the action of the primarily discharged anion of an inorganic salt upon an organic body are to be included among the simpler reactions, the results obtained so far in this domain have been very scanty, especially in regard to aromatic substances. The above-mentioned investigations of Elbs and Hertz, as well as those of Forster and Mewes on the electrolytic preparation of iodoform, 

Benzene.—Re nard,1 by the anodical action of the current in.an alcohol-sulphuric-acid solution of benzene with platinum anodes, obtained a body melting at 171° which Gattormunn and Friedrichs2 recognized later as hydroquinone. The hitter is also formed (Kempf3) if a mixture of benzene and n 1() T sulphuric acid is electrolyzed at lead-peroxide anodes and lead or zinc cathodes. Quinone is first produced at the anode with the aid of the lead peroxide. It is then reduced at the cathode to hydroquinone. 

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