Radiolysis of methylcyclohexane. IV. Effects of carbon tetrachloride and nitrous oxide in the vapor phase

Abstract

There is a radiation-induced chain reaction in methylcyclohexane (MCH) – CCl4mixtures in the vapor phase at 110° and 380 Torr. The chain-propagation products are chloroform and methylcyclohexylchloride (Gmax ≈ 40) and the chain-termination products are mainly methylcyclohexene (MC), bimethylcyclohexyl (C14), and hexachloroethane, depending on the composition of the mixture. At CCl4concentrations < 1 mole%, HCl is formed mainly by reaction of Cl−with positive ions, e.g. Cl− + C7H14+ → HCl + C7H13. The value of the ratio G(MC)/G(C14) is 8 ± 1 in pure MCH and in the mixtures up to 44 mole% CCl4.There is a radiation-induced chain reaction in MCH–N2O mixtures in the vapor phase. At 110° and 380 Torr, G(N2) = 22, G(MC) = 16, and G(C14) = 1.6, independent of N2O concentration between 2 and 10 mole%. The G-values are independent of MCH pressure between 50 and 520 Torr. Product formation is inhibited by the addition of SF6or DI. The half-life of the ion N2O−with respect to decomposition to N2 + O−is 10−4–10−3s under these conditions. It is suggested that the mechanism contains the reactions[Formula: see text][Formula: see text]Reaction [24] is slightly exothermic. Reaction [25] is exothermic if the electron affinity of N2O is greater than that of C7H13.