Role of the V-(V)/O-1(2) complex in oxidative reactions in the H2O2/V-(v)/AcOH system: Oxidation of alkenes and anthracenes

Anthracene and its alkyl derivatives undergo oxidation in the V-(V)/H2O2/Ac OH system via a nonradical mechanism through the intermediate formation of the vanadium(V) complex with singlet dioxygen as a ligand. The O-1(2) molec ule is transferred from this complex to an unsaturated substrate. The free singlet dioxygen O-1(2)((1)Delta (g)) is almost inactive toward anthracene in AcOH solution. Consequently, the vanadium(V) complex with singlet dioxyg en is the only oxidant species active in the reaction. The ratio between th e rate constant of the reaction of this complex with 2-ethylanthracene and the rate constant of its deactivation is an order of magnitude greater than the ratio between the rate constant of the reaction of dissolved free sing let dioxygen with the same substrate and the rate constant of its deactivat ion (physical quenching).