The specifics of the antioxidant action mechanism of cyclopentane anneled tetrahydroquinolines

The kinetics and mechanism of the antioxidant action of 4-(3-chlorophenyl)-3a,4,5,9b-tetrahydro-3H-cyclopenta[c]quinoline (5), 4-ethoxycarbonyl-8-fluoro-3a,4,5,9b-tetrahydro 3H-cyclopenta[c]quinolone (6), 4-ethoxycarbonyl-3a,4,5,11b-tetrahydro-3H-cyclopenta[c][1,7]phenantroline (7) have been studied in a model reaction of radical-chain oxidation of 1,4-dioxane by oxygen of air. Kinetic characteristics in the form of rate constants have been obtained, quantitatively characterizing the effectiveness of their antioxidant action. The nature of the active centers of the molecules in the series of compounds studied as antioxidants responsible for the elementary act of chain termination in oxidizing 1,4-dioxane has been established. The results obtained allow for the establishment of the mechanism of the antioxidant action of a wide class of quinoline derivatives, including those molecules possessing two or more active centers, and also enable the quantitative estimation of the contribution of each of the active centers of such molecules to the rate of the elementary stage of chain termination in the reaction of oxidation of organic compounds, and also opens up new perspectives in the creation of biologically active substances with desired properties.