Determination of the bond dissociation energy, D(CH3Hg—CH3), by the toluene carrier method

1969 ◽  
Vol 47 (6) ◽  
pp. 991-994 ◽  
Author(s):  
R. J. Kominar ◽  
S. J. Price
Keyword(s):  
Thermal Decomposition ◽  
Excellent Agreement ◽  
Rate Constant ◽  
Pressure Range ◽  
Arrhenius Equation ◽  
Flow System ◽  
Methyl Radicals ◽  
Exponential Factors ◽  
Pressure Independent

The thermal decomposition of Hg(CH3)2 has been studied in a toluene carrier flow system over the pressure range 4.5 to 323 mm at temperatures of 422 to 527 °C. The Arrhenius equation for the pressure independent region,[Formula: see text]is in excellent agreement with earlier work on the fully inhibited decomposition at lower temperatures. The region of fall off of the unimolecular rate constant is in agreement with a classical Kassel calculation using s = 16−18, but the rate of fall off requires the use of a curve with s = 3, displaced five log units to the left. This is consistent with the previous results for the dissociation of ethane into two methyl radicals and is further evidence of the inability of the classical Kassel equation to represent the behavior of systems with high pre-exponential factors.

Determination of the Bond Dissociation Energy D(C2H5Hg—C2H5) by the Toluene Carrier Method

1971 ◽  
Vol 49 (20) ◽  
pp. 3367-3374 ◽  
Author(s):  
A. C. Lalonde ◽  
S. J. W. Price
Keyword(s):  
Excellent Agreement ◽  
Arrhenius Equation ◽  
Flow System ◽  
Material Balance ◽  
Partial Solution ◽  
Complete Analysis ◽  
Product Analysis ◽  
Good Material ◽  
Good Agreement

The pyrolysis of diethylmercury has been studied in a toluene carrier flow System from 601 to 673 °K using total pressures of 1.04 to 7.75 mm. The progress of the reaction was followed by measuring the amounts of unreacted alkyl. Partial solution of butane in the toluene condensed at the outlet of the reactor made full product analysis difficult. Complete analysis in a number of runs did yield a good material balance between alkyl decomposed and [Formula: see text].[Formula: see text][Formula: see text][Formula: see text][Formula: see text]The Arrhenius equation for reaction 1, log k1(s−1) = 15.4 − (45 700 ± 1 000)/2.3 RT, is in excellent agreement with that estimated by Benson and O'Neal. Based on a number of simplifying approximations, log k3(cm3mol−1s−1) = 10.9 − (9 300 ± 2 000)/2.3 RT. The estimated disproportionation to combination ratio, K5/K4 = 0.09 – 0.12 is in good agreement with earlier work.Approximate correction of E1 to absolute zero yields D(C2H5Hg—C2H5) = 43.7 kcal mol−1 and therefore by difference D(Hg—C2H5) = 6.5 kcal mol−1.

The Rate of Recombination of H Atoms in the Presence of NH3

1973 ◽  
Vol 51 (22) ◽  
pp. 3771-3773 ◽  
Author(s):  
L. Teng ◽  
C. A. Winkler
Keyword(s):  
Rate Constant ◽  
Pressure Range ◽  
Flow System ◽  
Carrier Gas ◽  
A Value ◽  
Fast Flow

The rate constant for the homogeneous recombination of H atoms in the presence of NH3, with He as carrier gas, has been determined at 298°K in a fast flow system, over the pressure range 1.50 to 4.55 Torr, using e.s.r. technique. A value of either 4.00 × 1016 or 5.14 × 1016 cm6 mol−2 s−1 was calculated, depending upon the rate constant taken, or estimated, from the literature for the recombination in the presence of helium.

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.

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]

THE PYROLYSIS OF TRIMETHYLTHALLIUM

1965 ◽  
Vol 43 (7) ◽  
pp. 1961-1967 ◽  
Author(s):  
M. G. Jacko ◽  
S. J. W. Price
Keyword(s):  
Activation Energy ◽  
Rate Constant ◽  
Total Pressure ◽  
Flow System ◽  
Total Darkness ◽  
Methyl Radicals ◽  
Kcal Mole ◽  
Homogeneous Process ◽  
Carrier Flow ◽  
Reaction Proceeds

The pyrolysis of trimethylthallium has been studied in a toluene carrier flow system from 458 to 591 °K using total pressures from 5.6 to 33.0 mm. The progress of the reaction was followed by measuring the amount of methane, ethane, ethylene, and ethylbenzene formed and, in 21 runs, by direct thallium analysis. All preparative and kinetic work was carried out in total darkness where possible. A shielded 10 W lamp was used when some illumination was necessary.The decomposition is approximately 80% heterogeneous in an unconditioned vessel and 14–27% heterogeneous in a vessel pretreated with hot 50% HF for 10 min. The reaction proceeds by the simple consecutive release of three methyl radicals. The rate constant depends only slightly on the total pressure in the system so that the activation energy of the homogeneous process, 27.4 kcal/mole, may be equated to D[(CH3)2Tl—CH3].

Thermal decomposition of citraconic anhydride

1971 ◽  
Vol 24 (4) ◽  
pp. 771 ◽  
Author(s):  
NJ Daly ◽  
F Ziolkowski
Keyword(s):  
Carbon Dioxide ◽  
Thermal Decomposition ◽  
Gas Phase ◽  
Rate Constant ◽  
Arrhenius Equation ◽  
Volume Ratio ◽  
Reaction Vessel ◽  
First Order ◽  
First Order Kinetics ◽  
Citraconic Anhydride

Citraconic anhydride decomposes in the gas phase over the range 440- 490� to give carbon dioxide, carbon monoxide, and propyne which undergoes some polymerization to trimethylbenzenes. The decomposition obeys first-order kinetics, and the Arrhenius equation ������������������� k1 = 1015.64 exp(-64233�500/RT) (s-1) describes the variation of rate constant with temperature. The rate constant is unaffected by the addition of isobutene or by increase in the surface/volume ratio of the reaction vessel. The reaction appears to be unimolecular and if a diradical intermediate is involved it may not be fully formed in the transition state.

Determination of Conditions for the Suppression of CH3 + Sb(CH3)2→Sb(CH3)3 and Evaluation of D[(CH3)2Sb—CH3]

1972 ◽  
Vol 50 (7) ◽  
pp. 966-971 ◽  
Author(s):  
S. J. W. Price ◽  
J. P. Richard
Keyword(s):  
Activation Energy ◽  
Least Squares ◽  
Flow System ◽  
Heterogeneous Reaction ◽  
Methyl Radicals ◽  
Product Analysis ◽  
Temperature Range ◽  
Carrier Flow

The pyrolysis of trimethylantimony has been studied in a toluene carrier flow system over the temperature range 690–803 °K (total pressures 3.6–173.4 mm, contact times 1.0–13.5 s, decomposition 3.9–89.5%). The progress of the reaction was followed by measuring the amount of methane, ethane, and ethylbenzene formed. In 23 runs the undecomposed alkyl was also determined. The quantity found was in agreement with that expected from the product analysis if three methyl radicals are released for each molecule undergoing reaction. No heterogeneous reaction was detected.Deuterium labeling led to the conclusion that regeneration of the parent alkyl occurred during the course of the decomposition. This regeneration reaction was effectively eliminated by working at toluene pressures above 150 mm. Least squares analysis of the results obtained under conditions where regeneration should not be important givenLog10k/s−1 = 15.33 − (55 900 ± 1 000)/2.3RTThe activation energy should be a good approximation to D[(CH3)2Sb—CH3].Significant decomposition of SbCH3 probably does not occur. It seems most likely that free Sb is formed via 2Sb(CH3) → Sb(CH3)2 + Sb.

Methods for studying radical polymerization. Part. II. The volumetric and spectrophotometric determination of the rate constant of thermal decomposition of azo initiators

Polimery ◽  
2002 ◽  
Vol 47 (01) ◽  
pp. 22-29 ◽  
Author(s):  
JERZY SZAFKO ◽  
BARBARA PABIN-SZAFKO ◽  
KAROLINA ONDERKO ◽  
EWA WISNIEWSKA
Keyword(s):  
Thermal Decomposition ◽  
Radical Polymerization ◽  
Spectrophotometric Determination ◽  
Rate Constant ◽  
Azo Initiators

Determination of the rate constant of reaction of N(4S32) with NO2 using resonance fluorescence in a discharge flow system

1982 ◽  
Vol 69 (3) ◽  
pp. 381-388 ◽  
Author(s):  
Yoko Ono ◽  
Michael A.A. Clyne
Keyword(s):  
Rate Constant ◽  
Flow System ◽  
Resonance Fluorescence ◽  
Discharge Flow

Determination of D[(CH3)3Pb—CH3] by the Toluene Carrier Method

1972 ◽  
Vol 50 (16) ◽  
pp. 2639-2641 ◽  
Author(s):  
K. M. Gilroy ◽  
S. J. Price ◽  
N. J. Webster
Keyword(s):  
Least Squares ◽  
Flow System ◽  
Methyl Radicals ◽  
Product Analysis ◽  
Method Of Least Squares ◽  
Temperature Range ◽  
Carrier Flow

The pyrolysis of tetramethyl lead has been studied in a toluene carrier flow system over the temperature range 671–753 °K (contact times 0.72–1.67 s, 3–77% decomposition). The reaction was followed by measuring the amount of methane, ethane, and ethylbenzene formed. Comparison of the extent of reaction based on product analysis and on alkyl recovery indicates that approximately four methyl radicals are released for each molecule undergoing reaction 1.[Formula: see text]The method of least squares gives k1 = 5.0 × 1014 exp (−49 400/RT) sB1 with an estimated uncertainty of ± 1 000 cal mol−1 in E1. Under the conditions used E1 should be a reasonable measure of D[(CH3)3Pb—CH3].

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