THE THERMAL DECOMPOSITION OF ETHANE: PART I. INITIATION AND TERMINATION STEPS

1966 ◽  
Vol 44 (4) ◽  
pp. 505-514 ◽  
Author(s):  
M C. Lin ◽  
M. H. Back
Keyword(s):  
Thermal Decomposition ◽  
High Pressure ◽  
Rate Coefficients ◽  
First Order ◽  
Temperature Range ◽  
Order Rate ◽  
Ethyl Radical ◽  
Initiation Reaction ◽  
Ethyl Radicals

The rates of production of methane and butane in the pyrolysis of ethane have been measured over the temperature range 550–620 °C and at pressures of 40–600 mm. At high pressure the rates of formation of both products were first order in ethane, but below 200 mm the first-order rate coefficients decreased. The ratio of methane to butane was consistent with the interpretation that methane is a measure of the initiation reaction and that the combination and disproportionation of ethyl radicals is the main termination step. The order of the decomposition of the ethyl radical with respect to ethane varied between 0.38 and 0.59. The results are discussed in terms of the mechanism of the overall process.

THE THERMAL DECOMPOSITION OF ETHANE: PART II. THE UNIMOLECULAR DECOMPOSITION OF THE ETHANE MOLECULE AND THE ETHYL RADICAL

1966 ◽  
Vol 44 (20) ◽  
pp. 2357-2367 ◽  
Author(s):  
M. C. Lin ◽  
M. H. Back
Keyword(s):  
High Pressure ◽  
Rate Constant ◽  
Order Rate Constant ◽  
Methyl Radicals ◽  
Unimolecular Decomposition ◽  
First Order ◽  
Order Rate ◽  
Ethyl Radical ◽  
Lower Temperature ◽  
Ethyl Radicals

The rate of the elementary dissociation of ethane into two methyl radicals has been measured in its pressure-dependent region at temperatures from 913–999 °K and at pressures from 1–200 mm. The high-pressure first-order rate constant obtained by extrapolation was in agreement with that obtained at lower temperatures,[Formula: see text]Comparison with calculated Kassel curves showed that the best fit of the data was obtained with the Kassel parameter s = 12 ± 1. The high-pressure first-order rate constant for the decomposition of the ethyl radical was obtained by extrapolation of the data reported in Part I, assuming the rate constant for combination of ethyl radicals is independent of temperature.[Formula: see text]From the measured constant for the dissociation of ethane, the rate constant for the combination of methyl radicals was calculated and compared with the values measured in a lower temperature region. Differences in the values of the rate constants and in the shapes of the unimolecular falloff curves are discussed.

The Initial Stages of the Pyrolysis of Dimethyl Ether

1975 ◽  
Vol 53 (18) ◽  
pp. 2742-2747 ◽  
Author(s):  
Philip D. Pacey
Keyword(s):  
Dimethyl Ether ◽  
Rate Constant ◽  
Arrhenius Plot ◽  
Flow System ◽  
Order Rate Constant ◽  
Chain Termination ◽  
Rate Coefficients ◽  
First Order ◽  
Order Rate ◽  
Initiation Reaction

Dimethyl ether was pyrolized in a flow system at 782–936 K and 25–395 Torr with conversions from 0.2–10%. Product analyses were consistent with a simple Rice–Herzfeld mechanism with most chain termination by the recombination of CH3 radicals. The rate coefficients for both the initiation and termination reactions appeared to be slightly pressure dependent. The first-order rate constant for the initiation reaction,[Formula: see text]calculated from the rate of C2H6 formation, was k1 = 1015.0±0.5exp (−318 ± 8 kJ mol−1/RT) s−1, corresponding to ΔHf0(CH3O) = −5 ± 8 kJmol−1. Comparison of CH4 and C2H6 yields enabled calculation of the rate constant for the reaction of CH3 with dimethyl ether. From 373−936 K, the Arrhenius plot for this reaction is a curve.

Thermal decomposition of propylene oxide

1968 ◽  
Vol 46 (14) ◽  
pp. 2454-2456 ◽  
Author(s):  
T. J. Hardwick
Keyword(s):  
Thermal Decomposition ◽  
Free Radicals ◽  
Propylene Oxide ◽  
First Order ◽  
Temperature Range ◽  
Rate Expression ◽  
Order Rate ◽  
Common Precursor

In the temperature range 402–425 °C, propylene oxide in a toluene medium decomposes to form propionaldehyde (60–70%), acetone (14%), and free radicals (25%). The ratio of products is invarient with temperature, suggesting a common precursor to all three products. Propionaldehyde further decomposes into free radicals. The first order rate expression for propylene oxide disappearance is3.7 × 1012 e−51900/RT s−1.

THE KINETICS OF THE DECOMPOSITION REACTIONS OF THE LOWER PARAFFINS: III. PROPANE

1938 ◽  
Vol 16b (11) ◽  
pp. 411-419 ◽  
Author(s):  
E. W. R. Steacie ◽  
I. E. Puddington
Keyword(s):  
Thermal Decomposition ◽  
High Pressure ◽  
Excellent Agreement ◽  
Rate Constants ◽  
Initial Pressure ◽  
First Order ◽  
Decomposition Reactions ◽  
Order Rate ◽  
Products Of Reaction ◽  
Kinetics Of

The kinetics of the thermal decomposition of propane has been investigated over a temperature range from 551° to 602 °C. The limiting high pressure first order rate constants are given by[Formula: see text]The first order rate constants fall off strongly with increasing percentage decomposition, and the rate decreases with decreasing pressure in a manner similar to the rate decrease in the decomposition of the butanes.Analyses of the products of reaction at various stages show them to be independent of temperature over the range examined, but to be affected by the initial pressure. This effect is undoubtedly due to the secondary hydrogenation of some of the initial products. The analytical results are in excellent agreement with those of Frey and Hepp.

Consecutive reactions in the thermal decomposition of phenylalkyldiazirines

1977 ◽  
Vol 55 (20) ◽  
pp. 3596-3601 ◽  
Author(s):  
Michael T. H. Liu ◽  
Barry M. Jennings
Keyword(s):  
Thermal Decomposition ◽  
Kinetic Parameters ◽  
Diazo Compounds ◽  
First Order ◽  
Temperature Range ◽  
Decomposition Reactions ◽  
Consecutive Reactions ◽  
Rate Processes ◽  
Subsequent Decomposition

The thermal decomposition of phenyl-n-butyldiazirine and of phenylmethyldiazirine in DMSO and in HOAc have been investigated over the temperature range 80–130 °C. The intermediate diazo compounds, 1-phenyl-1-diazopentane and 1-phenyldiazoethane respectively have been detected and isolated. The decomposition of phenyl-n-butyldiazirine and the subsequent decomposition of its product, 1-phenyl-1-diazopentane, are an illustration of consecutive reactions. The kinetic parameters for the isomerization and decomposition reactions have been determined. The isomerization of phenylmethyldiazirine to 1-phenyldiazoethane is first order and probably unimolecular but the kinetics for the subsequent reactions of 1-phenyldiazoethane are complicated by several competing rate processes.

THE THERMAL DECOMPOSITION OF PERACETIC ACID IN AROMATIC SOLVENTS

1963 ◽  
Vol 41 (7) ◽  
pp. 1826-1831 ◽  
Author(s):  
F. W. Evans ◽  
A. H. Sehon
Keyword(s):  
Thermal Decomposition ◽  
Rate Constant ◽  
Peracetic Acid ◽  
First Order ◽  
Aromatic Solvents ◽  
Temperature Range ◽  
Polymeric Compounds

The thermal decomposition of peracetic acid in toluene, benzene, and p-xylene was studied over the temperature range 75–95°C. The main products of decomposition were found to be CH4, CO2, CH3COOH; small amounts of methanol, phenols, and polymeric compounds were also detected.The rate of the overall decomposition was first order with respect to peracetic acid, and the results could be explained by postulating the participation of the two simultaneous reactions:[Formula: see text] [Formula: see text]The rate constant of reaction (1) was independent of the solvent, whereas k2 was dependent on the solvent. The ratio k2/k1 was about 10.

Models to Determine First-Order Rate Coefficients from Single-Well Push-Pull Tests

Ground Water ◽  
2006 ◽  
Vol 44 (2) ◽  
pp. 275-283 ◽  
Author(s):  
Martin H. Schroth ◽  
Jonathan D. Istok
Keyword(s):  
Rate Coefficients ◽  
First Order ◽  
Order Rate ◽  
Single Well ◽  
Pull Tests

ADDITION OF ETHYL RADICALS TO ETHYLENE

1957 ◽  
Vol 35 (7) ◽  
pp. 588-594 ◽  
Author(s):  
J. A. Pinder ◽  
D. J. Le Roy
Keyword(s):  
Activation Energy ◽  
Reaction Zone ◽  
Addition Reaction ◽  
Steric Factor ◽  
Square Root ◽  
Temperature Range ◽  
Ethyl Radical ◽  
Ethyl Radicals

The addition of ethyl radicals to ethylene has been studied in the temperature range 58° to 123 °C. The radicals were produced by the mercury photosensitized decomposition of hydrogen in the presence of ethylene, and the rate of the addition reaction was measured in terms of the rate of formation of n-hexane by the combination of ethyl and butyl radicals. Corrections were made for the non-uniformity of radical concentrations in the reaction zone. Assuming a negligible activation energy for the combination of two ethyl radicals, the activation energy for the addition reaction is 5.5 kcal. per mole; the steric factor, relative to the square root of the steric factor for ethyl radical combination, is 5.0 × 10−5.

Pyrolysis of Trifluoroacetaldehyde

1973 ◽  
Vol 51 (14) ◽  
pp. 2292-2296 ◽  
Author(s):  
Michael T. H. Liu ◽  
Leon F. Loucks ◽  
Robert C. Michaelson
Keyword(s):  
Thermal Decomposition ◽  
High Pressure ◽  
Free Radicals ◽  
Rate Equation ◽  
Pressure Dependence ◽  
Inert Gas ◽  
Order Process ◽  
First Order ◽  
Pressure Region ◽  
High Pressure Region

The thermal decomposition of trifluoroacetaldehyde has been studied over the 460–520 °C temperature range, and at pressures from 4 to 400 mm Hg. The experimental rate equation in the high-pressure region is of the form: Rate = k[CF3CHO]3/2 where[Formula: see text]The results are consistent with a mechanism initiated by a first order process and terminated by a second order recombination of two CF3 free radicals. At lower pressures (40 mm Hg), the ratio of kinit/kterm is pressure dependent and the overall order increases. The effects of added inert gas confirm this pressure dependence.

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