Radiation induced oxidation of some organic substances with molecular oxygen

Abstract

MANY studies deal with the radiation chemical oxidation of individual organic compounds. The oxidations of heptane, nonane [1, 2], iso-octane [3], di-isopropyl ether [4], unsaturated hydrocarbons [5, 6, 7] and cumene [8, 9] were investigated in detail. In 1958 N. A. Bakh and Tun TyarL'-ehzhen' [1, 2] by the example of oxidation of n-heptane and n-nonane, discovered temperature ranges in which processes of oxidation take place by different meehansisms: in the range of low temperatures by the radical non-chain mechanism, in the region of higher temperatures, by the radical chain mechanism. At sufficiently high temperatures, when processes of thermal oxidation can take place even without additional action, ionizing radiation reduces the induction period [10] and the effective activation energy [11]. This paper deals with processes which take place in each of the temperature ranges and with transition conditions from one mechanism of oxidation to another. According to the character of reactions, processes of oxidation can be differentiated as follows: genuine radiation processes correspond to the range of low temperatures, in which non-chain radical reactions take place; radiation-thermal processes correspond to the average temperature range and chain processes initiated by radiation are characteristic of those which are discontinued after irradiation; finally thermo-radiation processes taking place in the region of relatively high temperatures in which processes of thermal oxidation are accelerated by radiation. Genuine radiation oxidation. Radiation oxidation was studied in detail by oxidation of iso-octane, heptane, di-isopropyl ether and isoporopyl alcohol [12]. I t was found that, in the low temperature region the yield of oxidation products depends very little on temperature and is practically independent of dose rate. The effective activation energy of hydrogen peroxide formation in di-isopropyl ether is 1.1 kcal/mole, in iso-octane--0.6 kcal/mole. In view of the fact that the mechanism of formation of oxidation products have not been established with sufficient reliability, all discussion will be on the basis of hydrogen