Gas-Phase Radiolysis of n-Butane

Abstract

The γ‐ray radiolysis of n‐C₄D₁₀–n‐C₄H₁₀–I₂ mixtures has been investigated in the presence and in the absence of inert gases. Benzene has been added in a few experiments. In the direct and in the inert gas sensitized radiolyses, more than 95% of the propane is formed via the hydride transfer reaction: $${\mathrm{sec-C}}_3{\mathrm{H}}_7^{+}+{\mathrm{C}}_4{\mathrm{H}}_{10}\to {\mathrm{C}}_3{\mathrm{H}}_8+{\mathrm{C}}_4{\mathrm{H}}_9^{+}.$$ Part of the ethane, ethylene, and propylene can be ascribed to hydride transfer reactions involving C₂H₅⁺, C₂H₃⁺, and C₃H₅⁺, respectively. The yield of these fragments relative to that of the C₃H₇⁺ increases with the recombination energy of the added inert gas. A few photochemical and radiolytic experiments using CH₃CH₂CD₂CD₃ have been carried out in order to elucidate the mechanism of the molecular detachment processes. It can be calculated from the results that the relative yields of the fragments produced in the direct radiolysis do not exactly agree with those deduced from the mass spectrometric cracking pattern obtained at 70 eV. The discrepancy is largest for the fragments produced at a high appearance potential. The data also indicate that, in the radiolysis, the contribution of neutral excited molecule decomposition may be considerably less important than recently reported by Beck and Niehaus for pressures around 10^—5 mm Hg.