Oxidation of methyl oleate induced by 60Co γ-radiation. Part 1.—Pure methyl oleate

Abstract

The ⁶⁰Co γ-radiation-induced oxidation of pure methyl oleate at dose rates below 1.3 × 10¹⁸ eV 1.^–1sec^–1 has been shown to occur by a chain mechanism in which the O₂ absorbed is quantitatively converted to hydroperoxide at conversions up to about 8 %. The reaction has an overall activation energy of 6.4 kcal/mole, and involves a temperature-independent production of initiating radicals from methyl oleate with a G-value of 5.36. HO₂· radicals do not participate in the initiation reaction since the yield of radiolytic hydrogen(G= 1.01) from methyl oleate is unaffected by the presence of O₂. The appearance of a peak in the absorption spectrum at 219 mµ is attributed to α,β-unsaturated ketones produced in the chain-termination reaction. The rate of oxidation of methyl oleate dissolved in methyl stearate, for which G_radical was 5.24, increases linearly with the solute concentration.