INFLUENCE OF CONSTANT MAGNETIC FIELD ON THE INITIATION OF CHAIN OXIDATION OF UNSATURATED COMPOUNDS
The kinetic parameters of the effect of a constant magnetic field (0,3 - 0,6 T) on the initiation of radical chain oxidation of unsaturated compounds and their saturated analogs were obtained by the method of highly sensitive microvolumometry at 343 K. This effect begins to manifest itself at values of magnetic induction >0,3 T, and at 0,6 T it increases the initiation rate (Wi) by about 1,5 times. It also increases with chain length grows. These results indicate that an increase in the magnetic field strength leads to an increase in the release of radicals into the volume from the solvent cell. Quantum chemical analysis using the density functional theory in the DFT B3LYP/6-311G** approximation showed that the influence of the magnetic field strength on Wi turns out to be significant, since the probability of triplet-singlet conversion in the radical pair, which is initially in the triplet state, decreases. In this case, the probability of the reverse process, the singlet-triplet transition, should increase accordingly. In ordinary organic molecules, the excited triplet level has much higher energy than the main singlet level, and spin-forbidden singlet- triplet transitions are unlikely. In the presence of a constant magnetic field, the probability of the S-T+ and S-T- transitions will increase. An increase in the magnetic field strength (ME) increases the efficiency of the release of radicals from the cell, which leads to an increase in the initiation rate. The absolute values of the ME for unsaturated compounds and their saturated analogs are close, which is logical to associate with the same reaction centers of their alkyl and, accordingly, peroxyl radicals.