Hydrogen abstraction from toluene by methyl radicals and the pressure dependence of the recombination of methyl radicals

1970 ◽  
Vol 48 (8) ◽  
pp. 1269-1272 ◽  
Author(s):  
A. N. Dunlop ◽  
R. J. Kominar ◽  
S. J. W. Price
Keyword(s):  
Pressure Dependence ◽  
Reasonable Agreement ◽  
Pressure Range ◽  
Hydrogen Abstraction ◽  
Methyl Radicals ◽  
Third Body ◽  
Kcal Mole

Using dimethylzinc, dimethylmercury, and trimethylbismuth as sources of methyl radicals, values of k1/k21/2[Formula: see text]have been calculated from 338 to 610 °C over the pressure range 4.5–204 mm. M is predominantly toluene. The observed pressure dependence of reaction [2] is in agreement with that found when M = benzene, but is somewhat greater, and the fall-off occurs at higher pressures, than for ethane dissociation. However, reasonable agreement is obtained if it is assumed that the efficiency of toluene as a third body in reaction [2] is about 1/10th that of ethane.Extrapolation to infinite pressure, where it is assumed that E2 = 0and A2 = 1013.34 cm3 mole−1 s−1, gives E1 = 8.0 ± 0.3 kcal mole−1 and A1 = 1011.07 cm3 mole−1 s−1.

Hydrogen abstraction by methyl radicals from benzene and the pressure dependence of the recombination of methyl radicals

1967 ◽  
Vol 45 (2) ◽  
pp. 157-159 ◽  
Author(s):  
M. Krech ◽  
S. J. W. Price
Keyword(s):  
Pressure Dependence ◽  
Pressure Range ◽  
Hydrogen Abstraction ◽  
Methyl Radicals ◽  
Kcal Mole ◽  
Pressure Region

With dimethyl mercury and dimethyl cadmium as sources of methyl radicals, values of k1/k21/2 for the reactions [Formula: see text] [Formula: see text]have been calculated from 471 to 527 °C over the pressure range 0.3 to 16.2 cm. Extrapolation to the effective infinite pressure region, where it is assumed that E2 = 0, gives E1 = 9.3 kcal mole−1, log A1 = 10.8 (cc mole−1 s−1).

THE REACTIONS OF TRIFLUOROMETHYL RADICALS WITH PROPANE, n-BUTANE, AND ISOBUTANE

1956 ◽  
Vol 34 (2) ◽  
pp. 103-107 ◽  
Author(s):  
P. B. Ayscough ◽  
E. W. R. Steacie
Keyword(s):  
Rate Constants ◽  
Hydrogen Abstraction ◽  
Activation Energies ◽  
Methyl Radicals ◽  
Kcal Mole

A study of the reactions of trifluoromethyl radicals, produced by the photolysis of hexafluoroacetone, with propane, n-butane, and isobutane has been made. The rate constants of the hydrogen-abstraction reactions have been determined at temperatures between 27 °C and 119 °C and the activation energies found to be 6.5 ± 0.5, 5.1 ± 0.3, and 4.7 ± 0.3 kcal./mole respectively. These values are compared with those obtained for the reactions with methane and ethane, and with the corresponding reactions of methyl radicals.

Mercury-photosensitized decomposition of dimethyl ether. Part III. The combination of radicals

1967 ◽  
Vol 45 (22) ◽  
pp. 2775-2783 ◽  
Author(s):  
Leon F. Loucks
Keyword(s):  
Dimethyl Ether ◽  
Rate Constant ◽  
Pressure Dependence ◽  
Rate Coefficient ◽  
Methyl Radicals ◽  
Methyl Ethyl ◽  
Methyl Radical ◽  
Unimolecular Decomposition ◽  
Third Body ◽  
Methyl Ethyl Ether

As part of the study of the mercury-photosensitized decomposition of dimethyl ether, the combination of methyl radicals has been investigated in the temperature range 200 to 300 °C and at pressures between 3 and 300 mm Hg. For pressures of less than 100 mm the second-order rate coefficient for the combination of methyl radicals shows a pressure dependence. The pressure dependence agrees qualitatively with that observed by others, but occurs at somewhat higher pressures. Calculations for the Kassel equation using the Arrhenius parameters for ethane decomposition and fitted to the pressure dependence of the methyl radical combination show that the number of effective modes for ethane decomposition is 8 or 9. Carbon dioxide was found to be a quite ineffective third body for energy transfer. The results for the mercury-photosensitized decomposition of dimethyl ether have also been analyzed to obtain information about the combination of methyl radicals with methoxymethyl radicals. The combination of these radicals becomes pressure dependent at pressures less than about 15 mm. Kassel integrations based on the rate constant [Formula: see text]for the unimolecular decomposition of methyl ethyl ether at the C—C bond, and fitted to the observed pressure dependence of the combination reaction, lead to s = 10 for these reactions.The rate constant for the abstraction of a hydrogen atom by a methyl radical from dimethyl ether was found to be [Formula: see text]

Hydrogen abstraction by methyl radicals in glasses

1984 ◽  
Vol 78 ◽  
pp. 175 ◽  
Author(s):  
Takahisa Doba ◽  
Keith U. Ingold ◽  
Willem Siebrand ◽  
Timothy A. Wildman
Keyword(s):  
Hydrogen Abstraction ◽  
Methyl Radicals

THE REACTION OF METHYL RADICALS WITH FORMALDEHYDE

1959 ◽  
Vol 37 (9) ◽  
pp. 1462-1468 ◽  
Author(s):  
A. R. Blake ◽  
K. O. Kutschke
Keyword(s):  
Activation Energy ◽  
Kinetic Analysis ◽  
Addition Reactions ◽  
Methyl Radicals ◽  
Kcal Mole ◽  
A Value ◽  
Abstraction Reaction ◽  
Butyl Peroxide

The pyrolysis of di-t-butyl peroxide has been reinvestigated and used as a source of methyl radicals to study the abstraction reaction between methyl radicals and formaldehyde. At low [HCHO]/[peroxide] ratios the system was simple enough for kinetic analysis, and a value of 6.6 kcal/mole was obtained for the activation energy. At higher [HCHO]/[peroxide] ratios the system became very complicated, possibly due to the increased importance of addition reactions.

Hydrogen abstraction from neopentane by methyl radicals

1969 ◽  
pp. 1241 ◽  
Author(s):  
J. A. Kerr ◽  
D. Timlin
Keyword(s):  
Hydrogen Abstraction ◽  
Methyl Radicals

The homogeneous conversion of methane to higher hydrocarbons in the presence of ethylene in the temperature range 925–1023 K

1991 ◽  
Vol 69 (1) ◽  
pp. 37-42 ◽  
Author(s):  
Alain R. Bossard ◽  
Margaret H. Back
Keyword(s):  
Hydrogen Abstraction ◽  
Homogeneous System ◽  
Catalytic Reactions ◽  
The Other ◽  
Methyl Radicals ◽  
Temperature Range ◽  
Vinyl Radicals ◽  
Conversion Of Methane ◽  
Radical Distribution ◽  
Higher Hydrocarbons

Mixtures of ethylene and methane have been pyrolyzed in the temperature range 925–1023 K for the purpose of converting methane to higher hydrocarbons. Addition of methane to thermally-reacting ethylene increases the rate of formation of propylene but decreases the rates of formation of the other major products, ethane, acetylene, and butadiene. Hydrogen abstraction from methane is a major propagation reaction and causes a shift in the radical distribution from ethyl and vinyl radicals, the main radicals in the pyrolysis reactions of ethylene alone, to methyl radicals, which lead to the formation of propylene. At 1023 K with a pressure of ethylene of 6.5 Torr and of methane of 356 Torr, 1.5 mol of methane is converted to higher molecular weight products for every mole of ethylene reacted. The rate of conversion of methane in the homogeneous system is lower than in catalytic reactions but the product is entirely hydrocarbon and no methane is lost to carbon monoxide or carbon dioxide. Key words: methane, ethylene, kinetics, pyrolysis, fuels.

Aromatic oxidation by cobaltic acetate in acetic acid

1969 ◽  
Vol 47 (3) ◽  
pp. 387-392 ◽  
Author(s):  
Koichiro Sakota ◽  
Yoshio Kamiya ◽  
Nobuto Ohta
Keyword(s):  
Activation Energy ◽  
Electron Transfer ◽  
Acetic Acid ◽  
Bond Energy ◽  
Hydrogen Abstraction ◽  
Steric Factor ◽  
Benzyl Acetate ◽  
Kcal Mole ◽  
First Order ◽  
Reversible Electron Transfer

A detailed kinetic study of oxidation of toluene and its derivatives by cobaltic acetate in 95 vol% acetic acid is reported. The reaction was found to be profoundly affected by a steric factor and rather insensitive to the C—H bond energy. The order of reactivities of various alkylbenzenes is quite reversal to that of hydrogen abstraction reactions. The reaction was of first-order with respect to toluene, of second-order with respect to cobaltic ion and of inverse first-order with respect to cobaltous ion. The oxidation by cobaltic ion seems to proceed via an initial reversible electron transfer from toluene to cobaltic ion, yielding [Formula: see text] which is oxidized into benzyl acetate by another cobaltic ion. The apparent activation energy for toluene was found to be 25.3 kcal mole−1, and the same activation energy was found for ethylbenzene, cumene, diphenylmethane, and triphenylmethane.

Hydrogen abstraction from methane and its fluoro derivatives by methyl radicals

1987 ◽  
pp. 211-213 ◽  
Author(s):  
Emma Wünsch ◽  
José M. Lluch ◽  
Antonio Oliva ◽  
Juan Bertrán
Keyword(s):  
Hydrogen Abstraction ◽  
Methyl Radicals ◽  
Fluoro Derivatives
Sign in / Sign up

Export Citation Format

Share Document