Iron(III, II)-induced activation of dioxygen for the oxygenation of cyclohexene and related unsaturated hydrocarbons

Iron(II, III)-Catalyzed Oxidation of Limonene by Dioxygen

“…The formation of carvone and carveol is somewhat similar to our previously published results [43,47] on oxidation of unsaturated hydrocarbons, when the double bond was preserved and a ketene and an alcohol were the main products and only traces of an epoxide were formed. The present system, however, differs from the previous ones because of the formation of limonene oxide in large amount, which is comparable with the amount of ketone.…”

“…Voltammetric and UV-vis measurements show that limonene, even in the presence of dioxygen, reduces Fe(III)-complex to Fe(II) one, which is active catalysts. The reduction process of iron(III)-catalyst by substrates seems to occur relatively often, since it was also observed during the oxidation of cyclohexene [43] and N-alkylanilines [44]. Therefore, the phenomena should be taken into account in the processes, which use iron catalysts.…”

“…The formation of higher concentrations of the epoxide can be explained assuming that terpenes form more stable oxides than alkenes. In our previous paper on oxidations of alkenes by dioxygen catalyzed by [Fe II (bpy) 2 2+ ] solv [43] we postulated that the reactive species is an iron-hydroperoxo adduct. It is known that porphyrin iron-oxo adduct is responsible for alkene epoxidation [48,49].…”

“…Our ] MeCN } in base free acetonitrile activate dioxygen for oxidation of cyclohexene [43] to ketone and alcohol with relatively high yield. Moreover, the oxidized form of the catalyst is reduced by the substrate.…”

Electrochemical Catalytic Processes with Hydrogen Peroxide Showing Oxidative and Reductive Properties (Acting as Oxidant or Reductant)

“…We claimed that it was the first described case when HOOH acts as a reductant in electrochemical catalytic processes. In our investigations on activation of dioxygen and hydroperoxides Fe II (bpy) 3 2þ complex is frequently used as a catalyst [10,24,25]. Therefore, we have employed the complex as a redox system in electrochemical catalytic process.…”