The decomposition of dimethyl peroxide and the rate constant for CH3O + O2 → CH2O + HO2

Abstract

The decomposition of dimethyl peroxide (DMP) was studied in the presence and absence of added NO₂ to determine rate constants k₁ and k₂ in the temperature range of 391–432°K: The results reconcile the studies by Takezaki and Takeuchi, Hanst and Calvert, and Batt and McCulloch, giving log k₁(sec⁻¹) = (15.7 ± 0.5) ‐ (37.1 ± 0.9)/2.3 RT and k₂ ≈ 5 × 10⁴M⁻¹· sec⁻¹. The disproportionation/recombination ratio k_7b/k_7a = 0.30 ± 0.05 was also determined: When O₂ was added to DMP mixtures containing NO₂, relative rate constants k₁₂/k_7a were obtained over the temperature range of 396–442°K: A review of literature data produced k_7a = 10^9.8±0.5M⁻¹·sec⁻¹, giving log k₁₂(M⁻¹·sec⁻¹) = (8.5 ± 1.5) ‐ (4.0 ± 2.8)/2.3 RT, where most of the uncertainty is due to the limited temperature range of the experiments.