Benzene electrolytic oxidation

Anthracene-benzene biplanemers (119) were prepared through the electrolytic oxidative decarboxylation of (4 + 4) photocycloadducts between substituted anthracenes and 1,2-dihydrophthalic anhydrides [165,166] (Scheme 36). Chemiluminescence was observed for 119 only in the solid state at > 120°C, but not in a liquid phase, whereas 119 (X = F or Cl, Y = Z = H) were not chemiluminescent [167], Efficient chemiluminescence was observed in the photocycloreversion of all biplanemers tested in both phases. 

Hydro-quinol may be synthesized by any of the general methods. Of special interest is its synthesis by the electrolytic oxidation of benzene. It crystallizes in colorless prisms, m.p. 170°. With ferric chloride it gives no color reaction, but is oxidized to quinone, the same oxidation occurring in the air in alkaline solutions. It reduces Fehling s solution and its important use is as a reducing agent in photography. 

The further oxidation of phenol may also result in the formation of catechol, C,iH4(OH) (1 2). The transformation may be effected by fusion with sodinm hydroxide.85 The snbstance may also be obtained by oxidizing benzene with hydrogen peroxide in the presence of ferrous sulfate88 and by reducing o-benzoquinone with aqueous sulfurous acid in the cold.81 Quinol may be prepared from phenol by oxidation with potassium persulfate in alkaline solution.38 It can also be obtained directly from benzene by the electrolytic oxidation of an alcohol solution to which... 

It is often possible to convert aromatic hydrocarbons directly into quinones. According to a German patent376 / -benzoquinone is obtainable in 50-55% yield by heating benzene with moist lead dioxide in 100% sulfuric acid at 56° for 5 min, then pouring the mass on ice and extracting the quinone with chloroform this quinone can also be prepared by electrolytic oxidation of benzene, in 65% yield.377... 

Wallach found that azoxybenzene in presence of acids rearranges into 4-hydroxyazobenzene, but his main work was on terpenes, on which he published 126 papers. He studied limonene (and its tetrabromide), pinene, and terpineol. Limonene tetrabromide was independently discovered by Guillaume Adolphe Renard (Rouen 10 May 1846-April 1919), who also obtained methylcyclohexane from rosin spirit, and worked on the electrolytic oxidation of alcohol, turpentine, benzene, toluene, etc. (1880 f.). 

In 1859, Friedel electrolytically oxidized acetone and found a mixture of formic, acetic, and carbonic acids with evolution of carbon dioxide and oxygen at the anode in an acetone-sulfuric acid mixture. Further studies on ketones were not reported until 1931, when a similar study was carried out resulting in the formation of methane, ethane, and unsaturated hydrocarbons, in addition to carbon dioxide and oxygen at platinum anodes. The first anodic oxidation of benzene was reported in 1880, with the observation that the electrolytic oxidation of benzene in an ethanolic-sulfuric acid medium yielded unidentifiable substances. A few years later Gotterman and Friedrichs reported that hydrocarbons were obtained from the anodic oxidation of benzene in alcoholic-sulfuric acid solution at platinum anodes. 

The combination of anodic oxidation of benzene using the Ag(I)/Ag(II) mediator with cathodic oxidation of benzene using the Cu(I)/Cu(II) mediator in a single electrolytic cell produces p-benzoquinone selectively in both the anodic and the cathodic chambers [242]. Silver-mediator promoted electrooxidation of hydrocarbon has been attempted [243]. The kinetics of indirect oxidation of catechol and L-dopa with IrCl6 has been studied in polymer-coated glassy carbon [244]. 

Fig. 9.25. (a) Tafel plots of numerous reactions reduction of benzene, oxidation of Cu in solid electrolyte, reduction of NOj in molten salt, reduction of Fe CNJg,... 

FIG. 31. (a) Current voltage curve of the PbOi anode in electrolytes without and saturated with benzene and (b) potential dependence of current efficiency of benzene oxidation. 

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