THE KINETICS OF THE REACTION OF ATOMIC HYDROGEN WITH METHANE

1964 ◽  
Vol 42 (7) ◽  
pp. 1638-1644 ◽  
Author(s):  
J. W. S. Jamieson ◽  
G. R. Brown
Keyword(s):  
Activation Energy ◽  
Electric Discharge ◽  
Atomic Hydrogen ◽  
Flow System ◽  
Steric Factor ◽  
Primary Reaction ◽  
Kcal Mole ◽  
Hydrogen Atoms ◽  
Fast Flow ◽  
Kinetics Of

Reinvestigation of the reaction of hydrogen atoms, produced by electric discharge, with methane in a fast flow system has given an activation energy of 7.4 ± 1.1 kcal/mole and a steric factor of about 10−3 for the primary reaction, H + CH4 → H2 + CH3.

The decomposition of n -hexane II. By reaction with atomic hydrogen

1958 ◽  
Vol 243 (1235) ◽  
pp. 449-457
Keyword(s):  
Activation Energy ◽  
Atomic Hydrogen ◽  
Flow System ◽  
Product Distribution ◽  
Steric Factor ◽  
Hydrogen Atoms ◽  
Initial Product ◽  
Molecular Weights ◽  
Main Component ◽  
Product Fraction

The reaction of hexane with hydrogen atoms produced by mercury photosensitization, has been studied in a flow system at 300° C. About one-third of the products had molecular weights greater than that of hexane, and dodecane was the main component of this product fraction. Hydrogen: hexane ratios up to 55:1 were employed and in these conditions virtually all the quenching of excited mercury atoms was brought about by hydrogen. The activation energy and steric factor of the reaction C 6 H 14 + H = C 6 H 13 + H 2 are estimated at 6 kcal and 10 -4 , respectively. These values are in accord with those recently obtained for the corresponding reactions involving other n -paraffins. The initial product distribution was similar to that obtained in the mercury photosensitized decomposition of hexane and the findings suggest that products of lower molecular weight than hexane derive almost completely from thermal decomposition of hexyl radicals. ‘Atomic cracking’ appears to be of little importance at these high temperatures.

THE REACTION OF ACTIVE NITROGEN WITH ETHANOL

1965 ◽  
Vol 43 (4) ◽  
pp. 935-939 ◽  
Author(s):  
P. A. Gartaganis
Keyword(s):  
Flow System ◽  
Methyl Radicals ◽  
Kcal Mole ◽  
Hydrogen Atoms ◽  
Active Nitrogen ◽  
Condensed Discharge ◽  
Preliminary Study ◽  
Fast Flow ◽  
Ethyl Radicals ◽  
Water Hydrogen

The reaction of active nitrogen with ethanol has been investigated in the range 300 to 593 °K using a modified condensed-discharge Wood–Bonhoeffer fast-flow system. The only condensable products found in appreciable amounts were hydrogen cyanide and water. Hydrogen was the main noncondensable product. A very small amount of acetaldehyde was also formed along with traces of ethane, ethylene, methane, acetonitrile, cyanogen, and probably carbon monoxide. The overall activation energy is 3.4 kcal/mole. It is postulated that the mechanism consists of the formation of two fragments NC2H5 and OH, from which the condensable products result as follows:[Formula: see text]A number of products found in trace quantities are produced by concomitant reactions of the hydrogen atoms with methyl radicals, and with ethanol as well as by disproportionation of ethyl radicals to produce ethane and ethylene. A preliminary study of the reaction of active nitrogen with isopropanol indicated that the energy of activation is in line with the energies of activation of methanol and ethanol.

THE REACTION OF ACTIVE NITROGEN WITH METHANOL

1963 ◽  
Vol 41 (5) ◽  
pp. 1097-1103 ◽  
Author(s):  
M. J. Sole ◽  
P. A. Gartaganis
Keyword(s):  
Hydrogen Cyanide ◽  
Flow System ◽  
Main Reaction ◽  
Kcal Mole ◽  
Hydrogen Atoms ◽  
Active Nitrogen ◽  
Steric Factors ◽  
Additional Water ◽  
Fast Flow ◽  
Methane Carbon

The reaction of active nitrogen with methanol has been investigated at several temperatures in the range 30 to 480 °C using a fast-flow system. The only condensable products found in appreciable amounts were water and hydrogen cyanide. The overall activation energy is 3.0 and 3.2 kcal/mole and the steric factors 1.3 × 10−3 and 2.1 × 10−3 for streamline and turbulent flow respectively.It is postulated that the mechanism consists of the initial formation of a collision complex, [NCH3OH], which breaks down to two fragments, NCH3 and OH, from which the two condensable products are formed,[Formula: see text]Attack of the methanol molecules by hydrogen atoms resulting from the main reaction occurs to a lesser extent and is responsible for the production of small quantities of methane, carbon monoxide, and additional water.

THE REACTION OF NITROGEN ATOMS WITH HYDROGEN ATOMS

1962 ◽  
Vol 40 (2) ◽  
pp. 240-245 ◽  
Author(s):  
C. Mavroyannis ◽  
C. A. Winkler
Keyword(s):  
Atomic Hydrogen ◽  
Molecular Hydrogen ◽  
Pressure Range ◽  
Flow System ◽  
Hydrogen Bromide ◽  
Hydrogen Atoms ◽  
Active Nitrogen ◽  
Reaction Tube ◽  
Fast Flow ◽  
Hydrogen Stream

The reaction has been studied in a fast-flow system by the addition of atomic hydrogen to active nitrogen. Hydrogen atom concentrations were estimated from the maximum destruction of hydrogen bromide in the atomic hydrogen stream. The nitrogen atom consumption, in the reaction mixture, was determined by addition of nitric oxide at different positions along the reaction tube. A lower limit of 4.87 ± 0.8 × 1014 cc2mole−2sec−1 was derived for the rate constant of the reaction of nitrogen atoms with hydrogen atoms, over the pressure range 2.5 to 4.5 mm, in an unheated reaction tube, poisoned with phosphoric acid. No reaction between nitrogen atoms and molecular hydrogen was observed, even at 350 °C.

Kinetics of the Reaction of Atomic Hydrogen with Vinyl Chloride

1971 ◽  
Vol 49 (7) ◽  
pp. 1023-1026
Author(s):  
J. S. Tanner ◽  
J. W. S. Jamieson
Keyword(s):  
Hydrogen Chloride ◽  
Vinyl Chloride ◽  
Electric Discharge ◽  
Atomic Hydrogen ◽  
Reaction Rate ◽  
Hydrogen Atoms ◽  
Specific Reaction Rate ◽  
Flow Rates ◽  
Different Temperatures ◽  
Kinetics Of

The reaction of hydrogen atoms, produced by electric discharge, with vinyl chloride vapor has been studied at four widely different temperatures. Since the maximum yields of HCl at both 328 and 494 °C exceeded the flow rates of atomic hydrogen, the reaction was observed to have limited chain characteristics. The products were hydrogen chloride, ethylene, methane, and ethane. The specific reaction rate for HCl production was found to be about [Formula: see text] and that for production of ethylene plus ethane was found to be about [Formula: see text].

Vulcanization of Elastomers. 23. The Chemical Kinetics of Vulcanization Reactions and The Physical Properties of The Vulcanizates. I

1960 ◽  
Vol 33 (2) ◽  
pp. 335-341
Author(s):  
Walter Scheele ◽  
Karl-Heinz Hillmer
Keyword(s):  
Activation Energy ◽  
Physical Properties ◽  
Chemical Kinetics ◽  
Kcal Mole ◽  
First Order ◽  
Equilibrium Swelling ◽  
Kinetics Of ◽  
Kinetics Of Vulcanization ◽  
Limiting Value ◽  
Good Agreement

Abstract As a complement to earlier investigations, and in order to examine more closely the connection between the chemical kinetics and the changes with vulcanization time of the physical properties in the case of vulcanization reactions, we used thiuram vulcanizations as an example, and concerned ourselves with the dependence of stress values (moduli) at different degrees of elongation and different vulcanization temperatures. We found: 1. Stress values attain a limiting value, dependent on the degree of elongation, but independent of the vulcanization temperature at constant elongation. 2. The rise in stress values with the vulcanization time is characterized by an initial delay, which, however, is practically nonexistent at higher temperatures. 3. The kinetics of the increase in stress values with vulcanization time are both qualitatively and quantitatively in accord with the dependence of the reciprocal equilibrium swelling on the vulcanization time; both processes, after a retardation, go according to the first order law and at the same rate. 4. From the temperature dependence of the rate constants of reciprocal equilibrium swelling, as well as of the increase in stress, an activation energy of 22 kcal/mole can be calculated, in good agreement with the activation energy of dithiocarbamate formation in thiuram vulcanizations.

Insect blood-brain barrier: a radioisotope study of the kinetics of exchange of a liposoluble molecule (n-butanol)

1976 ◽  
Vol 64 (1) ◽  
pp. 119-130
Author(s):  
M. V. Thomas
Keyword(s):  
Activation Energy ◽  
Temperature Sensitivity ◽  
Nerve Cord ◽  
Previous Investigation ◽  
Time Course ◽  
Kcal Mole ◽  
Similar Time ◽  
Kinetics Of ◽  
Butanol Concentration ◽  
Good Agreement

About 90% of the butanol uptake by the cockroach abdominal nerve cord washed out with half-times of a few seconds, in good agreement with an electrophysiological estimate, and the temperature sensitivity suggested an activation energy of 3 Kcal mole-1. The remaining activity washed out far more slowly, with a similar time course to that observed in a previous investigation which had not detected the fast fraction. Its size was similar to the non-volatile uptake, and was considerably affected by the butanol concentration and incubation period. It apparently consisted of butanol metabolites, which could be detected by chromatography.

Reactions of free radicals with aromatic compounds in the gaseous phase. I. Kinetics of the reaction of methyl radicals with toluene

1964 ◽  
Vol 17 (12) ◽  
pp. 1329 ◽  
Author(s):  
MFR Mulcahy ◽  
DJ Williams ◽  
JR Wilmshurst
Keyword(s):  
Flow System ◽  
Methyl Radicals ◽  
Methyl Radical ◽  
Hydrogen Atoms ◽  
Methyl Group ◽  
Benzyl Radical ◽  
Toluene Molecule ◽  
Benzyl Radicals ◽  
Butyl Peroxide ◽  
Kinetics Of

The kinetics of abstraction of hydrogen atoms from the methyl group of the toluene molecule by methyl radicals at 430-540�K have been determined. The methyl radicals were produced by pyrolysis of di-t-butyl peroxide in a stirred-flow system. The kinetics ,agree substantially with those obtained by previous authors using photolytic methods for generating the methyl radicals. At toluene and methyl-radical concentrations of about 5 x 10-7 and 10-11 mole cm-3 respectively the benzyl radicals resulting from the abstraction disappear almost entirely by combination with methyl radicals at the methylenic position. In this respect the benzyl radical behaves differently from the iso-electronic phenoxy radical, which previous work has shown to combine with a methyl radical mainly at ring positions. The investigation illustrates the application of stirred-flow technique to the study of the kinetics of free-radical reactions.

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.

Kinetics of the addition of acids to olefins with and without boron fluoride catalysis

1967 ◽  
Vol 45 (1) ◽  
pp. 11-16 ◽  
Author(s):  
G. A. Latrèmouille ◽  
A. M. Eastham
Keyword(s):  
Activation Energy ◽  
Acetic Acid ◽  
Apparent Activation Energy ◽  
Trifluoroacetic Acid ◽  
Similar Rate ◽  
Ethylene Dichloride ◽  
Kcal Mole ◽  
Rate Law ◽  
Boron Fluoride ◽  
Kinetics Of

Isobutene reacts readily with excess trifluoroacetic acid in ethylene dichloride solution at ordinary temperatures to give t-butyl trifluoroacetate. The rate of the reaction is given, within the range of the experiments, by the expression d[ester]/dt = k[acid]2[olefin], and the apparent activation energy is about 6 kcal/mole. The rate of addition is markedly dependent on the strength of the reacting acid and is drastically reduced in the presence of mildly basic materials, such as dioxane. The boron fluoride catalyzed addition of acetic acid to 2-butene can be considered to follow a similar rate law, i.e. d[ester]/dt = k[acid·BF3]2[olefin], but only if some assumptions are made about the position of the equilibrium [Formula: see text]since only the 1:1 complex is reactive.

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