3170-61-4Relevant academic research and scientific papers
Experimental and Theoretical Studies of the C2H5 + O2 Kinetics
Wagner, Albert F.,Slagle, Irene R.,Sarzynski, Dariusz,Gutman, David
, p. 1853 - 1886 (1990)
The thermal reaction between C2H5 and O2, which yields both C2H5O2 and C2H4 + H2O has been studied both experimentally and theoretically.The experiments were conducted in a heatable tubular reactor coupled to a photoionization mass spectrometer.C2H5 was p
Tropospheric degradation chemistry of HCFC-123 (CF3CHCl2): A proposed replacement chlorofluorocarbon
Hayman,Jenkin,Murrells,Johnson
, p. 421 - 437 (2007/10/03)
HCFC-123 has been proposed as a replacement for some of the fully halogenated chlorofluorocarbons and other chlorinated hydrocarbons, which are being phased out under the Montreal Protocol. This paper reports laboratory studies which were undertaken to determine kinetic and mechanistic parameters of reactions involved in the atmospheric degradation of HCFC-123 and the use of these parameters in a 2D global model of the troposphere to evaluate the yields of products formed in the degradation. The experimental studies have made use of the laser flash photolysis technique with time-resolved ultra-violet absorption spectroscopy for the kinetic measurements and broad-band ultra-violet absorption spectroscopy for product characterization. Rate coefficients have been determined for the self-reaction of CF3CCl2O2 as (3.6 ± 0.5) x 10-12 cm3 mol-1 s-1 and for its reactions with HO2 and NO as (1.9 ± 0.7) x 10-12 cm3 mol-1 s-1 and (1.5-2.0) x 10-11 cm3 mol-1 s-1, respectively, at room temperature. Kinetic data have also been obtained for the reaction of CF3CCl2O2 with C2H5O2 and two channels have been identified; CF3CCl2O2 + C2H5O2 → CF3CCl2O + C2H5O + O2 k = (9 (-5+9) x 10-13 cm3 mol-1 s-1 and CF3CCl2O2 + C2H5O2 → CF3CCl2OH + CH3CHO + O2, k = (3.6 ± 0.5) x 10-12 cm3 mol-1 s-1. Studies undertaken using the Cl-initiated oxidation of HCFC-123 suggest that trifluoroacetyl chloride, CF3COCl, is the major product of the gas-phase degradation. The kinetic and mechanistic data have been used to formulate a chemical module of the degradation of HCFC-123 in the troposphere. The module has been incorporated into a 2D model of the global troposphere so that the potential atmospheric impact of using HCFC-123 can be assessed. HCFC-123 has been proposed as a replacement for some of the fully halogenated chlorofluorocarbons and other chlorinated hydrocarbons, which are being phased out under the Montreal Protocol. This paper reports laboratory studies which were undertaken to determine kinetic and mechanistic parameters of reactions involved in the atmospheric degradation of HCFC-123 and the use of these parameters in a 2D global model of the troposphere to evaluate the yields of products formed in the degradation. The experimental studies have made use of the laser flash photolysis technique with time-resolved ultra-violet absorption spectroscopy for the kinetic measurements and broad-band ultra-violet absorption spectroscopy for product characterization. Rate coefficients have been determined for the self-reaction of CF3CCl2O2 as (3.6±0.5)×10-12 cm3 mol-1 s-1 and for its reactions with HO2 and NO as (1.9±0.7)×10-12 cm3 mol-1 s-1 and (1.5-2.0)×10-11 cm3 mol-1 s-1, respectively, at room temperature. Kinetic data have also been obtained for the reaction of CF3CCl2O2 with C2H5O2 and two channels have been identified; CF3CCl2O2+C2H5O2→CF3CCl$ -2$/O+C2 H5O+O2, k = (9-5+9)×10-13 cm3 mol-1 s-1 and CF3CCl2O2+C2H5O2→CF3CCl$ -2$/OH+CH3 CHO+O2, k = (3.6±0.5)×10-12 cm3 mol-1 s-1. Studies undertaken using the Cl-initiated oxidation of HCFC-123 suggest that trifluoroacetyl chloride, CF3COCl, is the major product of the gas-phase degradation. The kinetic and mechanistic data have been used to formulate a chemical module of the degradation of HCFC-123 in the troposphere. The module has been incorporated into a 2D model of the global troposphere so that the potential atmospheric impact of using HCFC-123 can be assessed.
A Kinetic Study of the Reaction between Ethylperoxy Radicals and HO2
Maricq, M. Matti,Szente, Joseph J.
, p. 2078 - 2082 (2007/10/02)
Flash photolysis-time-resolved UV spectroscopy is used to measure the rate constant for the C2H5O2 + HO2 reaction over the temperature range of 210-363 K.The radicals are generated by photolysis of F2 in the presence of H2 and ethane.The rate constant for the F + C2H6 reaction is measured relative to the F + H2 reaction to be k1 = (7.1+2.1-1.6)*10-10e(-347+/-69)/T cm3 s-1.In order to ascertain time-resolved concentrations, the HO2 UV absorption cross section and its self-reaction rate constant have been remeasured.The UV cross section is in good agreement with previous reports, with ?max = 0.041 Angstroem2 at 203 nm.The self-reaction rate constant of k5 = (2.8+/-0.5)*10-13e(594+/-55)/T cm3 s-1 is in excellent agreement with the currenty recommended value.The rate constant for the C2H5O2 + HO2 reaction is k7 = (6.9+2.1-1.6)*10-13e(702+/-69)/T cm3 s-1.This result is discussed with regard to the discrepancy which exists between the two previous measurements of this rate constant.
Rate Constants for Reduction of substituted Methylperoxyl Radicals by Ascorbate Ions and N,N,N',N'-tetramethyl-p-phenylenediamine
Neta, P.,Huie, R. E.,Mosseri, S.,Shastri, L. V.,Mittal, J. P.,et al.
, p. 4099 - 4104 (2007/10/02)
Absolute rate constants (k) for reduction of substituted methylperoxyl radicals by ascorbate ions and by TMPD (N,N,N',N'-tetramethyl-p-phenylenediamine) in aqueous solutions have been determined by pulse radiolysis.The rate constants vary from 1E6 to 1E9 M-1 s-1, increasing as the electron-withdraving capacity of the substituent on the peroxyl group increases.Linear correlations are observed between log k and the Taft substituents ?* for a wide variety of substituents, but not all substituents fit the same line.In the case of ascorbate as reductant, the points for peroxyl radicals that contain halogens on the α-carbon lie on a different line (ρ*=0.41) than that for the other substituents (ρ*=1.25).In the case of TMPD there are alsotwo families of peroxyl radicals: Those comprimising the electron-donating groups Me through t-Bu (ρ=5.6) and those containing electron-withdrawing substituents (ρ*=0.64).
