10027-72-2Relevant articles and documents
Mechanism of the Ozonolysis of Ethylene-Acetaldehyde Mixtures
Choe, Jong-In,Painter, M. Kimberly,Kuczkowski, Robert L.
, p. 2891 - 2895 (1984)
Ethylene-1,1-d2 was ozonized in the presence of acetaldehyde.The yields of ethylene ozonide-d0, -d2, and -d4 and propylene ozonide-d0, and -d2 were determined by proton NMR, microwave spectroscopy, and manometric measurements.The ratio of propylene ozonide-d0/propylene ozonide-d2 decreased as the concentration of acetaldehyde increased.This indicates that an inverse kinetic secondary isotope effect is associated with the recombination reactions of the carbonyl oxide (Criegee intermediate).A kinetic model was employed to describe the Criegee reaction mechanism and to estimate the final product ratios.This model resulted in quantitative estimates of the KSIE for the carbonyl oxide, the relative dipolarophilicity of formaldehyde and acetaldehyde, and the cage effect upon primary ozonide decomposition.The inverse KSIE for the carbonyl oxide and formaldehyde in their recombination reaction is consistent with a concerted process.
Kinetic and Mechanistic Study of the Self Reaction of CH3OCH2O2 Radicals at Room Temperature
Jenkin, Michael E.,Hayman, Garry D.,Wallington, Timothy J.,Hurley, Michael D.,Ball, James C.,et al.
, p. 11712 - 11723 (1993)
The UV absorption spectrum and kinetics of the self reaction of CH3OCH2O2 at 298 K have been studied using both the modulated photolysis of Cl2/CH3OCH3/O2/N2 mixtures and the pulse radiolysis of SF6/CH3OCH3/O2 mixtures.The spectrum, characterized in the range 200-290 nm, is in good agreement with the single published determination.The observed second-order removal kinetics of CH3OCH2O2, k5obs, were found to be sensitive to both the variation of total pressure (17-760 Torr) and the composition of the reaction mixtures: 2CH3OCH2O2 -> 2CH3OCH2O + O2 (5a); -> CH3OCHO + CH3OCH2OH + O2 (5b).The kinetic studies and a detailed product investigation using long path length FTIR spectroscopy (T = 295 K; Cl2/CH3OCH3/O2/N2 system) provide evidence to support a mechanism involving the rapid thermal decomposition of CH3OCH2O by H atom ejection occurring in competition with the reaction with O2: CH3OCH2O (+M) -> CH3OCHO + H (+M) (6); CH3OCH2O + O2 -> CH3OCHO + HO2 (4).The complications in the measured values of k5obs in the present studies, and those reported previously, are believed to occur as a direct result of formation of H atoms from reaction 6.Accordingly, a pressure-independent value of k5 = (2.1 +/- 0.3)E-12 cm3 molecule-1 s-1 is derived for the elementary rate coefficient at 298 K, with identical values of the branching ratio α = k5a/k5 = 0.7 +/- 0.1 determined independently from the FTIR product studies and the modulated photolysis experiments.As part of this work, the rate coefficient for the reaction of Cl atoms with CH3OCH2Cl was found to be (2.9 +/- 0.2)E-11 cm3 molecule-1 s-1.
Dimethyl Ether Oxidation: Kinetics and Mechanism of the CH3OCH2 + O2 Reaction at 296 K and 0.38-940 Torr Total Pressure
Sehested, J.,Moegelberg, T.,Wallington, T. J.,Kaiser, E. W.,Nielsen, O. J.
, p. 17218 - 17225 (1996)
The title reaction was studied at 296 K and 0.38-940 Torr total pressure using a FTIR smog chamber technique.The overall rate constant for reaction of CH3OCH2 radicals with O2 may be written, k1 = kRO2 + kprod, where kRO2 is the rate constant for peroxy radical production and kprod is the rate constant for the production of other species from reaction 1. k1 was measured relative to the pressure independent reaction of CH3OCHJ2 radicals with Cl2 (k4).There was no discernible effect of pressure on k1 in the range 200 - 940 Torr.Between 200 and 2 Torr total pressure k1 decreased by approximately a factor of 2.For pressures below 2 Torr k1 was again independent of pressure.The reaction proceeds via the formation of an activated complex, CH3OCH2O2(excit.), that is either collisionally stabilized to form the peroxy radical, CH3OCH2O2, or undergoes intramolecular H-atom abstraction followed by decomposition to give two formaldehyde molecules and an OH radical: CH3OCH2 + O2 ->/ CH3OCH2O2 + M, CH3OCH2O2(excit.) -> CH2OCH2O2H(excit.) -> 2HCHO + OH.The products from this reaction were studied as a function of total pressure.The molar yield of formaldehyde increased from RO2,0/k4 = (1.97 +/- 0.28)E-19 cm3 molecule-1, kRO2,infinite/k4 = 0.108 +/- 0.004, and kprod.0/k4 = (6.3 +/- 0.5)E-2 where kRO2.0 and kRO2.infinite are the overall termolecular and bimolecular rate constants for formation of the CH3OCH2O2 radical and kprod.0 represents the bimolecular rate constant for the reaction of CH3OCH2 radicals with O2 to yield formaldehyde in the limit of low pressure.These data and absolute rate data from the literature were used to derive a rate constant for the reaction of CH3OCH2 radicals with Cl2 of (1.00 +/- 0.16)E-10 cm3 molecule-1 s-1.The results are discussed in the context of the use of dimethyl ether as an alternative diesel fuel.
