The process of lipid peroxidation (LPO) plays an extremely important role in the human body due to the fact that its uncontrolled development can lead to oxidative stress and a number of serious diseases. The traditional approach to the analysis of the mechanism and kinetics of LPO is based on the well-known ideas that emerged from the study of radical-chain oxidation of hydrocarbons in a homogeneous medium. However, the distinctive feature of LPO is that this process is heterogeneous and the processes of diffusion of active intermediates between the aqueous and hydrocarbon phases should play a significant role in it. In the present work, an attempt has been made to theoretically estimate the contribution of these processes to the oxidation kinetics of model substances used in practice in the study of LPO. In the course of the calculations, a quantum chemical and kinetic analysis of the role of hydroperoxyl radical in the radical-chain mechanism of oxidation of methyl linoleate in micelles was carried out. The molecular dynamics method shows the important role of changing the dynamic rigidity of a hydrocarbon fragment of a chain during the formation of a peroxyl radical and hydroperoxyl group during the oxidation of a substrate in a heterogeneous medium. Quantum chemical calculations of the thermodynamics of reactions involving $${{{\text{HO}}_{2}}^{ \cdot }}$$
 radicals and the effects of their solvation made it possible to estimate the kinetic constants of the reaction rates. Using kinetic modeling, their relative contribution to the oxidation kinetics was revealed. In this case, it is possible to explain a number of anomalies associated with the oxidation of polyunsaturated fatty acids and their esters in micelles compared with their oxidation in a homogeneous hydrocarbon medium.

Quantum chemical evaluation of the role of $${{{\text{HO}}_{2}}^{ \cdot }}$$ HO 2 · radicals in the kinetics of the methyl linoleate oxidation in micelles

The enthalpy change of disproportionation reaction of nitroxyl and peroxyl radicals was calculated by the DFT B3LYP/cc-pVDZ method. The regeneration of the corresponding hydroxylamine during the oxidation of unsaturated compounds inhibited by nitroxyl radicals is shown to be associated with the disproportionation of the nitroxyl and peroxyl radicals.

Quantum-chemical analysis of the disproportionation of nitroxyl and peroxyl radicals in oxidizing organic compounds

The Role of Solvation in the Kinetics and the Mechanism of Hydroperoxide Radicals Addition to π‐Bonds of 1,2‐Diphenylethylene and 1,4‐Diphenylbutadiene‐1,3

The rate constants and kinetic coefficients of inhibition (fkin) for olefins oxidized with the transition metal compounds (Mn) were measured by highly sensitive microvolumometry at 323 K in combination with kinetic modeling. The cyclic mechanism of the reactions of hydroxyl radicals with Mn leading to the multiple chain termination was confirmed as indicated by the observed effect of long-term inhibition of the oxidation of the substrates with Mn and obtained values of fkin > 102.

Catalytic inhibition of olefin oxidation with Mn and Cu compounds

The kinetics of oxidation (323 K) of bicycloolefins from the norbornene series: norbornene, vinylnorbornene, ethylidenenorbornene, and norbornadiene, inhibited by phenols (PhOH), aromatic amines (AmH), transition metal compounds (Men), or stable nitroxyl radicals of the piperidine series (>NO·), in chlorobenzene solutions have been studied. It has been found that the phenols are single-action inhibitors, whereas the amines, the transition metals, and the nitroxyl radicals repeatedly terminate oxidation chains. The results are explained in terms of phenomenology of the bicycloolefin oxidation process associated with the fact that peroxide radicals attack different reaction centers (π- and α-CH bonds), thereby resulting in the formation of different types of chain carrier radicals: low-molecular-weight hydroperoxide and polyperoxide radicals.

The mechanism of inhibited oxidation of norbornene series bicycloolefins

На основе экспериментальных результатов посоокислению винильных соединений с использованием программы кинетического моделирования «Кинетика2012» рассчитаны значенияконстант скорости присоединения к πсвязямданных соединений ряда перекисных радикалов. Показано, что донорный/акцепторный характер заместителя в αположении двойной связи винильного мономера существенно влияет наего реакционную способность. Получены удовлетворительные корреляции с использованиемσ

A. I. Rusakov

Papers

The mechanism of inhibited oxidation of norbornene series bicycloolefins

The reactivity of oxygenate vinyl monomers in radical addition reactions