Efficient oxidation of β‑carotene in μ-carbido diiron octapropyltetraazaporphyrin–tBuOOH system

Abstract The oxidative decomposition of β‑carotene mediated by μ-carbido diiron octapropyltetraazaporphyrin ([FeOPrTAP]2C)–tBuOOH system was investigated in benzene. Interaction between tBuOOH and the binuclear complex resulted in the generation of powerful high-oxidized species those are capable of oxidizing the employed substrate within the limits of several minutes. The explanation for such reactivity behavior involves the existence of a mixture of reactive intermediates in the reaction medium: more stable singly oxidized at the macrocyclic ligand π-cation radical as well as much more reactive dication species that is more contributing to the reaction rate. The introduction of imidazole into the coordination sphere of the initial diiron complex accelerates the β‑carotene destruction because of generation of a powerful high-oxidizing species, which is capable of oxidizing β‑carotene as well as the applied organic peroxide resulting in dioxygen release. Catalytic behavior of all the observed active intermediates was supported by recycling of the reaction under carotene adding. The quantitative characteristics of reactivity of studied systems were obtained and the possible reaction mechanisms were proposed.