924-52-7Relevant articles and documents
Relative-rate study of thermal decomposition of the 2-butoxyl radical in the temperature range 280-313 K
Libuda,Shestakov,Theloke,Zabel
, p. 2579 - 2586 (2007/10/03)
The competition between thermal decomposition (kdis) and reaction with O2 (kO2) has been studied for the 2-butoxyl radical in a newly built 210 L photoreactor constructed of quartz. 2-Butoxyl radicals were generated by continuous 254 nm photolysis of 2-butoxyl iodide in the presence of O2 and NO, using N2 as a buffer gas. Reaction educts and products were analysed by long-path (29 m) IR absorption using an FTIR spectrometer. The ratio kdis/kO2 was derived from the product ratios of acetaldehyde and butanone, corrected for small amounts of side products. At 280, 298, and 313 K and a total pressure of 1 bar (M = O2 + N2), kdis/kO2 was determined at O2 partial pressures between 100 and 1000 mbar. At all temperatures, there was a systematic increase of (kdis/kO2)eff ≡ (Δ[CH3CHO]corr × [O2]) / (2 × Δ[CH3C(O)CH2CH3]) with the partial pressure of O2 which possibly is the result of an additional O2 independent source of acetaldehyde (≈8% of the 2-butoxyl radicals reacting by either of the two competing pathways at 298 K, 1 bar). Pressure-dependence studies between 100 and 1000 mbar support the hypothesis that the additional acetaldehyde originates from the formation of 6-10% chemically activated 2-butoxyl radicals in the temperature range 280-313 K. Correction of (kdis/kO2)eff for the O2 independent yield of acetaldehyde results in kdis/kO2 = (6.8 ± 1.4) × 1017, (2.3 ± 0.5) × 1018, and (5.5 ± 1.1) × 1018 molecule cm-3 at 279.8, 298.2, and 313.5 K, respectively, leading to the Arrhenius expression kdis/kO2 = (2.0 ± 0.5) × 1026exp(-45.4 kJ mol-1/RT) molecule cm-3 at a total pressure of 1 bar. This temperature dependence of kdis/kO2 implies that, depending on temperature, either thermal decomposition or reaction with O2 is the major loss process of 2-butoxyl radicals under the conditions of the lower troposphere. Using literature values for kO2, kdis = 3.9 × 1012exp(-47.1 kJ mol-1/RT) s-1 is derived for a total pressure of 1 bar (M = N2 + O2), which compares very favourably with a recent theoretical estimate (ab initio + RRKM) by Somnitz and Zellner (H. Somnitz and R. Zellner, Phys. Chem. Chem. Phys., 2000, 2, 1907).
Formation of Organic Nitro-compounds in Flowing H2O2+NO2+N2+Organic Vapour Systems. Part 3.-Effects of O2 Addition on H2O2+NO2+N2+Alkane Systems
Baulch, Donald L.,Campbell, Ian M.,Chappel, Jonathan M.
, p. 617 - 628 (2007/10/02)
The effects of oxygen on the product distribution from the surface-initiated reactions in flowing mixtures of H2O2, NO2, N2 and RH, where RH=ethane, propane, n-butane and n-pentane, at 298 K have been studied.In the absence of O2, the principal products are the corresponding nitroalkane, alkyl nitrite and alkyl nitrate.In the presence of sufficiently large concentrations of O2, the predominant product is the alkyl nitrate and the only other products of significance, in some cases, are the corresponding carbonyl compounds.The variation of the product yields with / gives values for the rate-constant ratios k8/(k3+k4) for reaction at both primary and secondary radical sites:.Possible mechanisms by which the products are formed are discussed.
Alkyl Nitrate Formation from the NOx-Air Photooxidations of C2-C8 n-Alkanes
Atkinson, Roger,Aschmann, Sara M.,Carter, William P. L.,Winer, Arthur M.,Pitts, James N.
, p. 4563 - 4569 (2007/10/02)
The yields of alkyl nitrates formed in the NOx-air photooxidations of the homologous series of n-alkanes from ethane through n-octane have been determined at 299 +/- 2 K and 735 torr total pressure for two different chemical systems.Alkyl peroxy radicals were generated by reaction of the n-alkanes with OH radicals (generated from the photolysis of methyl nitrite in air) or Cl atoms (from photolysis of Cl2 in air).The alkyl nitrate yields obtained from the two systems, corrected for secondary reactions, were in agreement within the experimental errors and increased monotonically with the carbon number of the n-alkane, from x-air photooxidations of the large n-alkanes.
