Magnetic Field Effect on the Oxidation of Unsaturated Compounds by Molecular Oxygen

Abstract

A quantum-chemical analysis of the effect of a constant magnetic field on radical formation in the processes of chain oxidation of organic compounds by molecular oxygen is presented. The calculation of the total electronic energies and thermodynamic functions of the compounds involved in the reactions was performed by the density functional method with the hybrid exchange-correlation functional of Becke, Lee, Yang and Parr DFT B3LYP/6-311G** using the NWChem software package. The effect of the magnetic field on the individual stages of chain oxidation is associated with the evolution of radical pairs. It is assumed that the dipole–dipole interaction in a radical pair is not averaged by the diffusion of radicals and should be taken into account. To a large extent, the magnetic field effect (MFE) value is influenced by the ratio between the relaxation time of the oscillatory-excited state in the radical pair (tvib) and the relaxation time of the inter-combination transitions (tst). Although the developed technique refers to liquid-phase reactions, it can be used to study the MFE for oxidation of biologically significant compounds in multiphase systems, such as micelles, liposomes and membranes.

Influence of a Constant Magnetic Field on the Mechanism of Adrenaline Oxidation

“…In accordance with [11,[25][26][27][28], the influence of a magnetic field increases the disproportionation rate constant of superoxide radicals, lowers their concentration, which leads to a drop in W. By intercepting O 2…”

“…The spin state of a radical pair can change due to spin evolution, for example, due to the Zeeman interaction of electron spins with an environment (with magnetic field, in this case [2,9,33,34]). In accordance with [2,9,11,[26][27][28]33,34], magnetic field reduces the probability of recombination and cross-recombination of radical pairs. Therefore, the oxidation rate should increase with increase in field strength.…”

“…Based on the above literature data [2,9,11,17,18,[25][26][27][28], it can be assumed that the magnetic field influence on the processes of auto-and initiated oxidation is expected to be realized for different key reactions and/or their probable superposition. In accordance with this assumption, the experimental approach to the studied transformations of adrenaline and analysis of the magnetic field effect was also formed.…”

“…The magnetic field effect (MFE) was determined as the ratio of the rates of initiated oxidation W 0 (H) in the applied magnetic field B = 0.3-0.6 T and in Earth's natural magnetic field W 0 (0): MFE = W 0 (H)/W 0 (0). Experiment details and installation design are described in our previous works [11,[25][26][27][28].…”

“…Almost no direct quantitative study of the kinetics of radical-chain oxidation of adrenaline by molecular oxygen has been carried out; there are no data on the effect of a magnetic field on this process. Although, this process has been studied in detail for other organic compounds and interpreted within the framework of the theory of radical pairs [8,9,11,[25][26][27][28].…”