Rates of OH Radical Reactions. I. Reactions with H2, CH4, C2H6, and C3H8 at 295 K

1975 ◽  
Vol 53 (22) ◽  
pp. 3374-3382 ◽  
Author(s):  
R. P. Overend ◽  
G. Paraskevopoulos ◽  
R. J. Cvetanović
Keyword(s):  
Gas Phase ◽  
Rate Constants ◽  
Flash Photolysis ◽  
Hydrogen Abstraction ◽  
Resonance Absorption ◽  
Oh Radicals ◽  
Oh Radical ◽  
Absolute Rate ◽  
Absorption Spectrophotometry ◽  
Secondary Reactions

A fast flash photolysis kinetic spectrophotometer capable of measuring rates of up to 105 s−1 is described. The rates of hydrogen abstraction from H2, CH4, C2H6, and C3H8 by OH radicals at 295 ± 2 K, have been measured in the gas phase by hydroxyl resonance absorption spectrophotometry. The influence of secondary reactions on the measured rates and the derivation of the absolute rate constants is discussed in detail.The absolute rate constants in units of cm3 mol−1 s−1 were found to be: [Formula: see text][Formula: see text][Formula: see text] and [Formula: see text]

A kinetic study of the reactions of OH radicals with fluoroethanes. Estimates of C—H bond strengths in fluoroalkanes

1983 ◽  
Vol 61 (5) ◽  
pp. 861-865 ◽  
Author(s):  
Jean-Pierre Martin ◽  
George Paraskevopoulos
Keyword(s):  
Kinetic Study ◽  
Gas Phase ◽  
Rate Constants ◽  
Flash Photolysis ◽  
Oh Radicals ◽  
Bond Dissociation Energies ◽  
Time Resolved ◽  
Dissociation Energies ◽  
Bond Strengths ◽  
Vacuum Uv

A kinetic study of the reactions of OH radicals with a series of fluoroethanes in the gas phase is presented. OH radicals were generated by flash photolysis of H2O vapor in the vacuum uv (λ > 165 nm) and were monitored in absorption by time-resolved attenuation of resonance radiation at 308.15 nm [OH(A2Σ+ → X2Π)]. The following absolute rate constants (in units of 109 cm3mol−1 s−1 at the 95% confidence limit) were determined at [Formula: see text][Formula: see text][Formula: see text][Formula: see text][Formula: see text]From a linear correlation of the present and previously published rate constants with bond dissociation energies, the following quantities (in kcal mol−1 at 298 K) were estimated to be: D(CH3CHF—H) = 96.3 ± 1.5, D(CH2FCHF—H = 98.8 ± 1.0, D(CF3CHF—H) = 103.5 ± 1.0, D(CHF2CF2—H) = 103.0 ± 1.5, and [Formula: see text][Formula: see text]

The Rate-Constant of the Reaction of Hydroxyl Radicals With Methanol, Ethanol and (D3)Methanol

1986 ◽  
Vol 39 (11) ◽  
pp. 1775 ◽  
Author(s):  
PG Greenhill ◽  
BV Ogrady
Keyword(s):  
Hydroxyl Radicals ◽  
Rate Constant ◽  
Flash Photolysis ◽  
Hydrogen Abstraction ◽  
Reaction Scheme ◽  
Resonance Absorption ◽  
Rate Coefficients ◽  
Secondary Reactions ◽  
Temperature Ranges ◽  
Predominant Process

The rate coefficients for hydrogen abstraction by hydroxyl radicals from methanol and ethanol have been determined in the temperature ranges 260-803 K and 255-459 K respectively. Flash photolysis combined with resonance absorption detection of OH was used to obtain results which may be described by the Arrhenius expressions:   Methanol ��� k(T) = (8.0�1.9)×10-12 exp[-(664�88)K/T]cm3 s-1 ������� (1)   Ethanol ���� k(T) = (1.25�0.24)×10-11 exp[-(360�52)K/T]cm3 s-1 (2)  The results obtained for methanol are in excellent agreement with results obtained by other workers, but the Arrhenius parameters for ethanol are markedly different to those obtained in the only other study of the temperature dependence of this reaction. The rate constant for reaction with (D3)methanolhas been determined at 293 K: (D3)Methanol ����� k(293) = 5.0�0.2×10-13 cm3 s-1 (3) The presence of an isotope effect confirms that the predominant process is abstraction of hydrogen from the carbon rather than the oxygen. The results obtained for the reaction with ethanol were analysed by using a 21 reaction scheme to determine the effect of [OH]O and secondary reactions on k(T). The simulations indicate that secondary reactions involving OH are relatively unimportant in determining the bimolecular rate coefficients found in this study.

Absolute rate constants for the gas-phase reaction of OH radicals with cyclohexane and ethane at 295 K

1986 ◽  
Vol 128 (2) ◽  
pp. 168-171 ◽  
Author(s):  
Ole J. Nielsen ◽  
Jette Munk ◽  
Palle Pagsberg ◽  
Alfred Sillesen
Keyword(s):  
Gas Phase ◽  
Rate Constants ◽  
Oh Radicals ◽  
Phase Reaction ◽  
Absolute Rate ◽  
Gas Phase Reaction

Rates of OH radical reactions. VII. Reactions of OH and OD radicals with n-C4H10, n-C4D10, H2 and D2, and of OH with neo-C5H12 at 297 K

1980 ◽  
Vol 58 (20) ◽  
pp. 2146-2149 ◽  
Author(s):  
George Paraskevopoulos ◽  
Wing S. Nip
Keyword(s):  
Gas Phase ◽  
Rate Constants ◽  
Room Temperature ◽  
Kinetic Isotope Effect ◽  
Flash Photolysis ◽  
Deuterium Atom ◽  
Oh Radicals ◽  
Confidence Limits ◽  
Kinetic Isotope ◽  
Absorption Technique

Absolute rate constants of hydrogen and deuterium atom abstraction by OH and OD radicals from n-C4H10, n-C4D10, H2 and D2, and by OH radicals from neo-C5H12 have been measured at room temperature in the gas phase using the flash photolysis-resonance absorption technique. The rate constants in units of cm3 mol−1 s−1 were found to be:[Formula: see text]The quoted errors are the 95% confidence limits. A kinetic isotope effect was observed when hydrogen was replaced by deuterium in the paraffin and H2, whereas there was no significant effect when OH was replaced by OD.

The reactions of O(3P) with acetonitrile and propionitrile

1995 ◽  
Vol 73 (5) ◽  
pp. 666-674 ◽  
Author(s):  
Suzanne Budge ◽  
John M. Roscoe
Keyword(s):  
Hydrogen Atom ◽  
Gas Phase ◽  
Rate Constant ◽  
Rate Constants ◽  
Hydrogen Atom Abstraction ◽  
Absolute Rate ◽  
Analytical Results ◽  
Absolute Rate Constant ◽  
Secondary Reactions ◽  
The Absolute

The reactions of O(3P) with acetonitrile and propionitrile have been studied kinetically in the gas phase as a function of temperature and nitrile concentration. The rate constants obtained experimentally for the consumption of O(3P) in these reactions, in the units L mol−1 s−1, obey the following relations: O + acetonitrile: In k = 20.98 ± 0.23 − 2100 ± 200/T; and O + propionitrile: In k = 21.01 ± 0.19 − 1900 ± 200/T. Mechanisms are discussed in which the reaction is initiated by hydrogen atom abstraction and in which initiation is by addition of O(3P) to the nitrile, followed by decomposition of the addition complex. The kinetic and analytical results are best explained by the mechanism in which the reactions are initiated by RCN + O → R + OCN. In the case of the reaction with acetonitrile, the absolute rate constant is smaller than the experimental value by a factor of 7 ± 20%, independent of temperature, as a result of secondary reactions. Keywords: kinetics, reactions of O(3P) with nitriles.

The gas-phase reaction of hydrazine and ozone: A nonphotolytic source of OH radicals for measurement of relative OH radical rate constants

1983 ◽  
Vol 15 (7) ◽  
pp. 619-629 ◽  
Author(s):  
Ernesto C. Tuazon ◽  
William P. L. Carter ◽  
Roger Atkinson ◽  
James N. Pitts
Keyword(s):  
Gas Phase ◽  
Rate Constants ◽  
Oh Radicals ◽  
Phase Reaction ◽  
Oh Radical ◽  
Gas Phase Reaction

Kinetics and Products of the OH Radical-Initiated Reaction of 1,4-Butanediol and Rate Constants for the Reactions of OH Radicals with 4-Hydroxybutanal and 3-Hydroxypropanal

2010 ◽  
Vol 44 (2) ◽  
pp. 707-713 ◽  
Author(s):  
Sherri A. Mason ◽  
Janet Arey ◽  
Roger Atkinson
Keyword(s):  
Rate Constants ◽  
Oh Radicals ◽  
Oh Radical
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