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.

Primary kinetic isotope effect in the gas phase photochlorination of ethyl chloride-1-d1

1984 ◽  
Vol 62 (5) ◽  
pp. 899-906 ◽  
Author(s):  
Jan Niedzielski ◽  
T. Yano ◽  
E. Tschuikow-Roux
Keyword(s):  
Activation Energy ◽  
Gas Phase ◽  
Isotope Effect ◽  
Ground State ◽  
Rate Constants ◽  
Kinetic Isotope Effect ◽  
Kinetic Isotope ◽  
Primary Reference ◽  
Hydrogen Deuterium ◽  
Increasing Temperature

The abstraction of hydrogen/deuterium from CH3CHDCl by ground state chlorine atoms produced photolytically from Cl2 has been investigated at temperatures betwen 280 and 368 K. The relative rates for the internal competition[Formula: see text]are found to conform to an Arrhenius rate law:[Formula: see text]These data, taken together with the external competition results for the C2H5Cl/CH3CHDCl system, in conjunction with the competitive results using CH4 as a primary reference, have yielded the rate constants (cm3 s−1):[Formula: see text]The relatively weak primary kinetic isotope effect, kH/kD, decreases with increasing temperature from 1,855 at 280 K to 1.66 at 365 K. The results are compared with those obtained based on the BEBO method. While both the trend and the magnitude of the kinetic isotope effect are satisfactorily predicted, the activation energy is not.

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]

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]

An experimental study of the reactivity of the hydroxide anion in the gas phase at room temperature, and its perturbation by hydration

1981 ◽  
Vol 59 (11) ◽  
pp. 1615-1621 ◽  
Author(s):  
Scott D. Tanner ◽  
Gervase I. Mackay ◽  
Diethard K. Bohme
Keyword(s):  
Experimental Study ◽  
Proton Transfer ◽  
Gas Phase ◽  
Rate Constants ◽  
Room Temperature ◽  
Gas Phase Reactions ◽  
Flowing Afterglow ◽  
Hydroxide Anion

Flowing afterglow measurements are reported which provide rate constants and product identifications at 298 ± 2 K for the gas-phase reactions of OH− with CH3OH, C2H5OH, CH3OCH3, CH2O, CH3CHO, CH3COCH3, CH2CO, HCOOH, HCOOCH3, CH2=C=CH2, CH3—C≡CH, and C6H5CH3. The main channels observed were proton transfer and solvation of the OH−. Hydration with one molecule of H2O was observed either to reduce the rate slightly and lead to products which are the hydrated analogues of the "nude" reaction, or to stop the reaction completely, k ≤ 10−12 cm3 molecule−1 s−1. The reaction of OH−•H2O with CH3—C≡CH showed an uncertain intermediate behaviour.

Reactions of trifluoromethyl radicals. V. Hydrogen abstraction from methyl acetate and methyl (2H3)Acetate

1980 ◽  
Vol 33 (7) ◽  
pp. 1437
Author(s):  
NL Arthur ◽  
PJ Newitt
Keyword(s):  
Isotope Effect ◽  
Rate Constants ◽  
Methoxy Group ◽  
Methyl Acetate ◽  
Kinetic Isotope Effect ◽  
Hydrogen Abstraction ◽  
Activation Energies ◽  
Temperature Range ◽  
Kinetic Isotope ◽  
Acetyl Group

Hydrogen abstraction by CF3 radicals from CH3COOCH3 and CD3COOCH3 has been studied in the temperature range 78-242°, and data have been obtained for the reactions: CF3 + CH3COOCH3 → CF3H+[C3H5O2] �������������(3) CF3 + CH3COOCH3 → CF3H+CH2COOCH3������������ (4) CF3 + CD3COOCH3 → CF3D+CD2COOCH3������������ (6) CF3 + CD3COOCH3 → CF3H+CD3COOCH2������������ (7) The corresponding rate constants, based on the value of 1013.36 cm3 mol-1 S-1 for the recombination of CF3 radicals, are given by (k in cm3 mol-1 s-1 and E in J mol-1): logk3 = (11.52�0.05)-(35430�380)/19.145T ���� (3)logk4 = (11.19�0.07)-(34680�550)/19.145T ���� (4)logk6 = (11.34�0.06)-(46490�490)/19.145T ���� (6)logk7 = (11.26�0.05)-(36440�400)/19.145T ���� (7)At 400 K, 59% of abstraction occurs from the acetyl group, and 41 % from the methoxy group. The kinetic isotope effect at 400 K for attack on the acetyl group is 25, due mainly to a difference in activation energies.

Rate constants for the gas–phase reactions of OH radicals with ethylene and halogenated ethylene compounds

1976 ◽  
Vol 65 (11) ◽  
pp. 4771-4777 ◽  
Author(s):  
Carleton J. Howard
Keyword(s):  
Gas Phase ◽  
Rate Constants ◽  
Oh Radicals ◽  
Gas Phase Reactions

Rate constants of the gas-phase reactions of OH radicals withtrans-2-hexenal,trans-2-octenal, andtrans-2-nonenal

2009 ◽  
Vol 41 (7) ◽  
pp. 483-489 ◽  
Author(s):  
Tingting Gao ◽  
Jean M. Andino ◽  
Carlos C. Rivera ◽  
Misaela Francisco Márquez
Keyword(s):  
Gas Phase ◽  
Rate Constants ◽  
Oh Radicals ◽  
Gas Phase Reactions

Rate constants for the gas-phase reaction of OH radicals with a series of ketones at 299 ± 2 K

1982 ◽  
Vol 14 (8) ◽  
pp. 839-847 ◽  
Author(s):  
Roger Atkinson ◽  
Sara M. Aschmann ◽  
William P. L. Carter ◽  
James N. Pitts
Keyword(s):  
Gas Phase ◽  
Rate Constants ◽  
Oh Radicals ◽  
Phase Reaction ◽  
Gas Phase Reaction
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