Petroleum complexes of metalloporphyrins and their dioxygen adducts

Porphyrin is the most studied tetrapyrrole-based compound. The cavity of porphyrin contains four pyrrolic nitrogen’s that are well suited to binding the majority of metal ions to form metalloporphyrin. The present work is devoted to the formation of petroleum-derived dioxygen and metalloporphyrin adducts in receptor compartments. Cyclodextrin is used as the receptor. It was determined that the oxidation reaction was selective and highly efficient, and that the clathrate compound was produced through noncovalent bonds. Cobalt, iron, nickel and manganese porphyrins have been shown to form dioxygen adducts with molecular oxygen. The structure and properties of dioxygen and metalloporphyrin adducts were studied for the first time. The dependence of the metalloporphyrin oxidation product yield on the number of receptors, reaction time, temperature, pressure, and nature of the solvent was studied. The above dependence shows that, unlike other metalloporphyrins, manganese-containing porphyrins are converted to dioxygen adducts with a high efficiency of 88 %. Based on experimental data, the equilibrium constant for the formation of dioxygen and petroleum metalloporphyrin adducts was calculated for the first time. It has been shown that the value of the equilibrium constant for the formation of adducts in the presence of the receptor exceeds the value of the equilibrium constant for oxygen reactions in the absence of the receptor by 4–5 points. In all metalloporphyrin complexes, a correlation in the formation of the peroxide structure of dioxygen adducts was established, which was confirmed by the presence in the IR spectrum of specific absorption bands characteristic of the fragment O2-2. Synthetic dioxygen adducts of metalloporphyrin compounds are of great interest because they transport synthetic oxygen.