The reaction of methoxy radicals with nitric oxide and nitrogen dioxide

By allowing dimethyl peroxide (10^?4M) to decompose in the presence of nitric oxide (4.5 × 10^?5M), nitrogen dioxide (6.5 × 10^?5M) and carbon tetrafluoride (500 Torr), it has been shown that the ratio k₂/k_2′ = 2.03 ± 0.47: CH₃O + NO → CH₃ONO (reaction 2) and CH₃O + NO₂ → CH₃ONO₂ (reaction 2′). Deviations from this value in this and previous work is ascribed to the pressure dependence of both these reactions and heterogeneity in reaction (2). In contrast no heterogeneous effects were found for reaction (2′) making it an ideal reference reaction for studying other reactions of the methoxy radical. We conclude that the ratio k₂/k_2′ is independent of temperature and from k₁ = 10^10.2±0.4M^?1 sec^?1 we calculate that k_2′ = 10^9.9±0.4M^?1 sec^?1. Both k₂ and k_2′ are pressure dependent but have reached their limiting high-pressure values in the presence of 500 Torr of carbon tetrafluoride. Preliminary results show that k₄ = 10.^9.0±0.6 10^?4.5±1.1/ΘM^?1 sec^?1 (Θ = 2.303RT kcal mole^?1) and by k₄ = 10^8.6±0.6 10^?2.4±1.1/ΘM^?1 sec^?1: CH₃O + O₂ → CH₂O + HO₂ (reaction 4) and CH₃O + t-BuH → CH₃OH + (t-Bu) (reaction 4′).