I. I. Moiseev

Mechanism of the inhibition of oxidation reactions by metal complexes. 9. Effect of coordination on the stoichiometry of chain rupture by aromatic amines

Conclusions1.By coordinating nickel(II) ions with the amino groups of anthranilic acid, it is possible to increase the stoichiometric coefficient for chain rupture in the oxidation of alcohols and aliphatic amines.2.By studying the initiated oxidation of cyclohexanol, n-octanol, and cyclohexylamine at 75–90°C, it has been possible to estimate stoichiometric coefficients and rate constants for chain rupture by complexes of nickel(II) with derivatives of anthranilic acid, by free ligands, and by diphenylamine derivatives.

Mechanism of the inhibition of oxidation by metal complexes

Conclusions1.A study has shown that tin tetraiodide repeatedly breaks the oxidation chains in the initiated oxidation of isopropylbenzene at 50–75‡C. Inhibition involves stoichiometric chain rupture through homolytic substitution of the iodine of SnI4 by peroxyl radicals, followed by multiple chain rupture by molecular iodine and alkyl iodides in processes involving alkyl and peroxyl radicals.2.Stoichiometric coefficients and rate constants have been determined for the reactions of peroxyl and alkyl radicals with SnI4 and molecular iodine, respectively.

The mechanism of oxidation inhibition by metal complexes 2. The effect of substituents in the schiff-base imine component on the antioxidant properties of copper salicylaldiiminates

Conclusions1.The copper bis(salicylaldiiminate)s are involved in repeated chain rupture acts in the course of the oxidation of cyclohexylamine by α-aminoperoxide radicals.2.Measured by the initiated oxidation method, the rate constants for one-electron oxidation and reduction of α-aminoperoxide radicals by Cu(I) and Cu(II) complexes diminish with an increase in the electron-donor activity of the substituent in the imine component of the coordinated Schiff base.3.Measured in this same way, the rate constant for chain rupture in the p,p′-substituted diphenylamines increases with an increase in the electron-donor activity of the substituent.

Mechanism of oxidation inhibition by metal complexes

1. n nIn oxidizing at 95–210°C, pentaerythrite esters of monocarboxylic acids follow a radical-chain mechanism with second-power chain breaking. Rate constants for chain extension and breaking have been determined; as have rate constants for hydroper oxide breakdown into free radicals. Effective rate constant for chain extension and breaking have been determined at 115°C. n n n n n2. n nA rate constant has been determined for cumene peroxide initiation at 110–140°C.