The γ-Ray Induced Oxidation of Aromatic Hydrocarbons in Liquid Dinitrogen Oxide

Abstract

Abstract The γ-ray induced oxidation of aromatic hydrocarbons has been studied in liquid dinitrogen oxide, mainly at −18°C. Various mixing ratios of dinitrogen oxide and four aromatic hydrocarbons have been examined. The main oxygen-containing products observed were the corresponding phenols and benzyl alcohols. The kinetic analysis showed that ionic species, probably N2O− ions, are the main precursors at low mole fractions of dinitrogen oxide and that oxygen atoms become important with an increase in the mole fraction. 1-Butene was used as a scavenger of oxygen atoms. The following rate constant ratios were obtained for the reactions of oxygen atoms and N2O− ions: k(O+toluene)/k(O+1-butene)=0.02, k(O+toluene)/k(O+benzene)=2.0, and k(N2O−+1-butene)/k(N2O−+toluene)=2.5. The relative rates for the formation of the corresponding phenols and benzyl alcohols through ionic reactions from aromatic hydrocarbons were obtained as follows: benzene, 1.0; toluene, 2.5; p-xylene, 2.2; 1,3,5-trimethylbenzene, 3.1. These values are quite different from the relative rate constants of the reactions of oxygen atoms with these aromatic hydrocarbons.