Tocopherol- and Ascorbic Acid–Inhibited Radical Chain Oxidation of Tetrahydrofuran

Abstract

The role of ascorbic acid and α-tocopherol in the radical chain oxidation of tetrahydrofuran at 309 K was studied. The reaction was initiated by \(2,2{\kern 1pt} '\)-azobisisobutyronitrile. The rate of the process was monitored by oxygen consumption. The rate constant of the reaction of the tetrahydrofuran peroxyl radical with α-tocopherol was measured to be k₇ = (2.9 ± 0.6) × 10⁵ L mol^–1 s^–1. The effect of an aqueous solution of ascorbic acid on the rate of tetrahydrofuran oxidation was studied. The rate constant of the reaction of the tetrahydrofuran peroxyl radical with ascorbic acid was measured to be k₇ = (10.2 ± 1.0) × 10⁴ L mol^–1 s^–1. The effect of ascorbic acid on the α-tocopherol-inhibited oxidation of tetrahydrofuran was examined. It was shown that, when both inhibitors are used together, the induction period is equal to the sum of the induction periods of the individual compounds. The effective inhibition rate constant in this case is k₇ = (2.5 ± 0.5) × 10⁵ L mol^–1 s^–1.