The oxidation of some alkylbenzenes by the hydroxyl radical, which is produced by the reaction of Fe2+ with H2O2 electrogenerated from O2 in aqueous solution, was carried out. In the reaction, Fe3+, generated by the above reaction, is also reduced to Fe2+ at the potential of reduction of O2. The reaction products are hydroxylated products of the aromatic rings and side-chain oxidation products. In the oxidation of toluene at [H+] = 0.2M, the yield of the former was higher than that of the latter, whereas the opposite was observed in the oxidations of ethylbenzene and cumene. From the results obtained at [H+] = 0.001M, it appears that α-hydrogen abstraction from the side chains by the hydroxyl radical might make a certain contribution to the formation of side-chain oxidation products. The current efficiencies at low concentration of Fe2+ were very high, and the yields of the corresponding alcohols were very low, indicating that the carbonyl compounds were produced by the reaction between intermediate radicals and O2 dissolved in the solution. The relatively high yield of the meta-isomer under O2 saturated in solution can be explained by the fast addition of O2 to hydroxycyclohexadienyl radical followed by elimination of HO2 to yield phenolic products. Although the influence on the addition of α-cyclodextrin to the electrolyte solution on the regio-selectivity of phenol formation was small, it was observed that the para-isomer forms are slightly high.
- Fenton's reagent
- hydroxyl radical
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Renewable Energy, Sustainability and the Environment
- Surfaces, Coatings and Films
- Materials Chemistry