THE REACTION OF METHYL RADICALS WITH ACETALDEHYDE

1955 ◽  
Vol 33 (4) ◽  
pp. 699-704 ◽  
Author(s):  
R. E. Dodd
Keyword(s):  
Rate Constant ◽  
Methyl Radicals

The rates of formation of methane and ethane in the photodecomposition of acetaldehyde have been measured between 391 and 564 °K. The rate constant for the reaction[Formula: see text]was found to be[Formula: see text]

The reaction of hydrogen atoms with ethylene

1970 ◽  
Vol 316 (1527) ◽  
pp. 575-591 ◽  
Keyword(s):  
Hydrogen Atom ◽  
Rate Constant ◽  
Recombination Reaction ◽  
Methyl Radicals ◽  
Methyl Radical ◽  
Hydrogen Atoms ◽  
Ethyl Radical ◽  
Cracking Reaction ◽  
Computer Calculations ◽  
First Time

A detailed study has been made of the products from the reaction between hydrogen atoms and ethylene in a discharge-flow system at 290 ± 3 K. Total pressures in the range 8 to 16 Torr (1100 to 2200 Nm -2 ) of argon were used and the hydrogen atom and ethylene flow rates were in the ranges 5 to 10 and 0 to 20 μ mol s -1 , respectively. In agreement with previous work, the main products are methane and ethane ( ~ 95%) together with small amounts of propane and n -butane, measurements of which are reported for the first time. A detailed mechanism leading to formation of all the products is proposed. It is shown that the predominant source of ethane is the recombination of two methyl radicals, the rate of recombination of a hydrogen atom with an ethyl radical being negligible in comparison with the alternative, cracking reaction which produces two methyl radicals. A set of rate constants for the elementary steps in this mechanism has been derived with the aid of computer calculations, which gives an excellent fit with the experimental results. In this set, the values of the rate constant for the addition of a hydrogen atom to ethylene are at the low end of the range of previously measured values but are shown to lead to a more reasonable value for the rate constant of the cracking reaction of a hydrogen atom with an ethyl radical. It is shown that the recombination reaction of a hydrogen atom with a methyl radical, the source of methane, is close to its third-order region.

THE REACTION BETWEEN METHYL RADICALS AND ISOBUTANE

1961 ◽  
Vol 39 (10) ◽  
pp. 1920-1928 ◽  
Author(s):  
A. R. Blake ◽  
J. F. Henderson ◽  
K. O. Kutschke
Keyword(s):  
Rate Constant ◽  
Apparent Rate Constant ◽  
Methyl Radicals

It has been confirmed that the apparent rate constant for the reaction between methyl radicals, produced by the photolysis of deuterated acetone, and isobutane increases with decreasing isobutane pressure. An explanation is proposed to account for this observation suggesting that the production of methane by disproportionation between methyl and t-butyl radicals was not negligible as has been assumed previously.

The Rate-Constant for the Recombination of Methyl Radicals

1986 ◽  
Vol 39 (8) ◽  
pp. 1257 ◽  
Author(s):  
NL Arthur ◽  
JC Biordi
Keyword(s):  
Experimental Data ◽  
High Pressure ◽  
Rate Constant ◽  
Rate Constants ◽  
The Other ◽  
Methyl Radicals ◽  
Experimental Conditions ◽  
Temperature Range ◽  
Best Value ◽  
Limiting Value

Rate constants for the recombination of CH3 radicals have been measured by means of the rotating sector technique in the temperature range 373- 463 K, and at a pressure of 30 Torr . CH3 radicals were produced by the photolysis of acetone, and the experimental data were fitted to sector curves generated from Shepp's theory. The results give kb = (2.81�0.22)×1013 cm3 mol-1 s-1, which, under the chosen experimental conditions, is close to its high-pressure limiting value. A comparison is made with the other values of the rate constant reported in the literature, and a best value is suggested.

The Oxidation of Formyl Radicals

1974 ◽  
Vol 29 (2) ◽  
pp. 251-255 ◽  
Author(s):  
N. Washida ◽  
Richard I. Martinez ◽  
Kyle D. Bayes
Keyword(s):  
Steady State ◽  
Rate Constant ◽  
Reaction Times ◽  
Initial Growth ◽  
Methyl Radicals ◽  
Absolute Rate ◽  
Atmospheric Reactions ◽  
Low Concentrations ◽  
Absolute Rate Constant ◽  
State Concentration

Steady state concentrations of formyl radicals were measured with a photoionization mass spectrometer. The reaction of ethylene with oxygen atoms in a system free of O2 was used to form CHO and CH3. Preliminary experiments showed that the reaction of methyl radicals did not interfere with the CHO measurements. By using low concentrations of O and short reaction times, it was possible to observe the initial growth of the CHO concentration. From the rate of approach of CHO to its steady state concentration, the absolute rate constant for the reaction O + CHO was determined to be (2.1+0.4)×10-10 cm3 molecule-1 sec-1. Addition of molecular oxygen to this system caused a decrease in the steady state CHO concentration, due to the reaction, CHO+O2→HO2+C0 as was suggested by Groth and coworkers in 1938. The rate constant for this reaction was calculated to be (5.7±1.2)×10-12 cm3 molecule-1 sec-1. The importance of these rate constants for combustion and atmospheric reactions are discussed briefly.

A method for the direct determination of the rate constants for radical-radical interactions in the gas phase II. The rate constant for the recombination of methyl radicals

1957 ◽  
Vol 243 (1232) ◽  
pp. 130-142 ◽  
Keyword(s):  
Gas Phase ◽  
Rate Constant ◽  
Room Temperature ◽  
Direct Determination ◽  
Theoretical Interpretation ◽  
Methyl Radicals ◽  
Gas Phase Reactions ◽  
A Value ◽  
Acetone Vapour

The technique outlined in part I of this paper has been employed to study the photo­sensitized decomposition of acetone vapour. A theoretical interpretation of the non-stationary state applied to non-chain photochemical gas phase reactions with second-order termination has been given and the effects of non-homogeneous absorption of radiation have been considered. A value has been obtained for the rate constant for the recombination of methyl radicals in the gas phase at room temperature.

Photolyse du méthyl-2-butène-1, du méthyl-3-butène-1 et du cis-pentène-2 à 174, 163 et 147 nm

1979 ◽  
Vol 57 (8) ◽  
pp. 863-869 ◽  
Author(s):  
Guy J. Collin ◽  
Hélène Deslauriers ◽  
Sylvain Auclair
Keyword(s):  
Double Bond ◽  
Photon Energy ◽  
Rate Constant ◽  
Pressure Effect ◽  
Low Pressure ◽  
Decomposition Process ◽  
Fragmentation Process ◽  
Quantum Yields ◽  
Methyl Radicals ◽  
Hydrogen Atoms

Photolysis of 2-methyl-1-butene (M2B1), cis-2-pentene (CP2), and 3-methyl-1-butene (M3B1) has been systematically studied at 163 nm. Pressure effect has been measured at 147, 163, and 174 nm. The main fragmentation process of the photoexcited olefine is the C—C split of the bond located in position β relative to the double bond:[Formula: see text] α-Methallyl radicals obtained in the M3B1 and CP2 photolysis decompose partly at low pressure, giving rise to the formation of 1,3-butadiene and hydrogen atoms. β-Methallyl radicals decompose also at low pressure into allene and methyl radicals. Butadiene and allene quantum yields follow the Stern–Volmer law, and this allows us to determine the ratio of the rate constant of dissociation relative to the rate constant of stabilization, kd/ks, through collision of the α- and β-methallyl radicals. From these values, we conclude that the excess of photon energy is not statistically distributed into the fragments, and that the decomposition process follows one (or several) particular law(s).

The Reaction of Methyl Radicals with Neopentane

1973 ◽  
Vol 51 (15) ◽  
pp. 2415-2422 ◽  
Author(s):  
Philip D. Pacey
Keyword(s):  
Rate Constant ◽  
Flow Reactor ◽  
Arrhenius Plot ◽  
Reactor System ◽  
Methyl Radicals ◽  
Temperature Ranges ◽  
Initiation Reaction ◽  
Good Agreement

Neopentane was pyrolyzed in a flow reactor system at 793–953 K and 20–400 mm Hg. The rate constant for the initiation reaction,[Formula: see text]calculated from the observed C2H6 yield, was 1017.7±0.3 exp (−356 ± 6 kJ mol−1/RT)s−1, in good agreement with earlier determinations in other temperature ranges. The rate constant of the reaction,[Formula: see text]calculated from the observed CH4 and C2H6 yields, was 1010.5 ± 0.1 exp (−67 ± 2 kJ mol−1/RT) 1 mol−1 s−1, four to ten times faster than predicted on the basis of earlier work at 404–608 K. From 404–953 K, the Arrhenius plot for this reaction is strongly curved.

The Reaction of Methyl Radicals with Molecular Hydrogen

1974 ◽  
Vol 52 (21) ◽  
pp. 3665-3670 ◽  
Author(s):  
Peter C. Kobrinsky ◽  
Philip D. Pacey
Keyword(s):  
Rate Constant ◽  
Molecular Hydrogen ◽  
Arrhenius Plot ◽  
Flow System ◽  
Methyl Radicals

Mixtures of neopentane and hydrogen were pyrolyzed in a flow system at 826–968 K and 27–400 mm Hg. Measurements of the yields of CH4 and C2H6 at various conditions enabled calculation of the rate constant for[Formula: see text]at 926 and 829 K. The Arrhenius plot of these and earlier measurements from 372 to 1370 K is a curve, which can be represented by[Formula: see text]

Sign in / Sign up

Export Citation Format

Share Document