Reactions of radicals. XXI. Relative rate constants for hydrogen abstraction by methyl radicals from substituted toluenes

1969 ◽  
Vol 34 (6) ◽  
pp. 2018-2020 ◽  
Author(s):  
William A. Pryor ◽  
Umberto Tonellato ◽  
Daniel L. Fuller ◽  
Sandra Jumonville
Keyword(s):  
Rate Constants ◽  
Relative Rate ◽  
Hydrogen Abstraction ◽  
Methyl Radicals ◽  
Relative Rate Constants ◽  
Substituted Toluenes

The addition of methyl radicals to ethylene, propylene, the butenes and higher 1-olefines

1957 ◽  
Vol 240 (1222) ◽  
pp. 396-407 ◽  
Keyword(s):  
Double Bond ◽  
Carbon Atom ◽  
Rate Constants ◽  
Relative Rate ◽  
Methyl Radicals ◽  
Active Hydrogen ◽  
Hydrogen Atoms ◽  
Methyl Group ◽  
Ethylene Propylene ◽  
Relative Rate Constants

The addition of methyl radicals to ethylene and its homologues in iso -octane solution was studied over the temperature range 55 to 85°C. The relative rate constants of addition to ethylene, propylene and iso -butene determined at 65°C are 34, 22 and 36 respectively. Taking into account the statistical factor of 2 for ethylene, we conclude that the increasing ease of addition for this series of olefines reflects the increasing stability of the produced radicals. The rates of addition to trans - and cis -butene-2 are significantly lower (6.9 and 3.4 respectively), indicating a steric hindrance resulting from the presence of a methyl group on the carbon atom on which the reaction takes place. Identical rates of addition were found for propylene, butene-1,pentene-1, 3 methyl butene-1, heptene-1, decene-1 and hexadecene-1, indicating that the rates of addition are not affected by the length and the shape of the hydro­carbon ‘tail’. The rates of abstraction of hydrogen atoms by methyl radicals were determined. It was found that the rate constants for active hydrogen ( α to C=C double bond) fall into three distinctive classes characterizing the primary, the secondary, and the tertiary hydrogen atoms.

Relative rate constants for abstraction of hydrogen by methyl radicals from ethane and from ethylene

1988 ◽  
Vol 66 (4) ◽  
pp. 578-583 ◽  
Author(s):  
S. I. Ahonkhai ◽  
M. H. Back
Keyword(s):  
Rate Constants ◽  
Relative Rate ◽  
Previous Measurement ◽  
Methyl Radicals ◽  
Lower Range ◽  
Thermal Reactions ◽  
Temperature Range ◽  
A Value ◽  
Relative Rate Constants

A method is described for the measurement of relative rate constants for abstraction of hydrogen by methyl radicals from ethane and from ethylene based on the effect of the addition of small quantities of ethane on the rates of formation of products in the thermal reactions of ethylene. The ratio of rate constants for reactions[Formula: see text]over the temperature range 673–733 K was given by the following expression:[Formula: see text](R = 1.987 cal mol−1 deg−1). Using a value of k4, from the literature the following expression was obtained for k3, over the same range of temperature:[Formula: see text]It was concluded that a previous measurement of k3 in a lower range of temperature was too close to the value of k4.

Kinetics of the successive chlorination of 1,2-dichloroethane in the liquid phase

1969 ◽  
Vol 22 (6) ◽  
pp. 1177 ◽  
Author(s):  
DS Caines ◽  
RB Paton ◽  
DA Williams ◽  
PR Wilkinson
Keyword(s):  
Liquid Phase ◽  
Rate Constants ◽  
Relative Rate ◽  
Stirred Tank ◽  
Continuous Stirred Tank Reactor ◽  
Alternative Pathways ◽  
Tank Reactor ◽  
Relative Rate Constants ◽  
Continuous Stirred Tank ◽  
Kinetics Of

Liquid 1,2-dichloroethane has been chlorinated by dissolved chlorine to a succession of chloroethanes up to the ultimate hexachloroethane. The results of both batch and continuous stirred tank reactor systems have been analysed by computer techniques to give a set of relative rate constants from which one can predict the product composition for a given chlorine uptake, the aim in this work being to optimize the production of tetrachloroethanes. An unusual feature of the kinetics is that 1,1,1,2- and 1,1,2,2-tetrachloroethanes provide alternative pathways between 1,1,2-trichloroethane and pentachloroethane.

RECOMBINATION OF OPPOSITELY CHARGED AQUEOUS CLUSTER IONS USING ELECTROSTATICALLY MERGED ION BEAMS

1996 ◽  
Vol 03 (01) ◽  
pp. 655-660 ◽  
Author(s):  
B. PLASTRIDGE ◽  
K.A. COWEN ◽  
D.A. WOOD ◽  
M.H. COHEN ◽  
J.V. COE
Keyword(s):  
Rate Constants ◽  
Cluster Size ◽  
Collision Energy ◽  
Relative Rate ◽  
Center Of Mass ◽  
Cluster Ions ◽  
Charged Cluster ◽  
Relative Rate Constants ◽  
Oppositely Charged ◽  
Electrostatic Quadrupole

A new method for studying cluster-cluster interactions is introduced which involves merging mass-selected beams of oppositely charged cluster ions with an electrostatic quadrupole deflector. Recombination is monitored by measuring the rate of fast neutral production. Relative rate constants have been measured for the reaction of H 3O+( H 2 O )n+ OH −( H 2 O )m as a function of cluster size (m=n=0–3), which display a pronounced enhancement with clustering. Relative rate constants have also been measured as a function of center-of-mass collision energy for a heavily clustered reaction (n=3, m=3) and a lightly clustered reaction (n=1, m=0) revealing that clustering produces a dramatic change in the reaction mechanism.

REACTION OF OXYGEN ATOMS WITH BUTADIENE

1960 ◽  
Vol 38 (11) ◽  
pp. 2187-2195 ◽  
Author(s):  
R. J. Cvetanović ◽  
L. C. Doyle
Keyword(s):  
Pressure Dependence ◽  
Rate Constants ◽  
Room Temperature ◽  
Relative Rate ◽  
Excess Energy ◽  
General Mechanism ◽  
Arrhenius Parameters ◽  
Heats Of Reaction ◽  
Relative Rate Constants ◽  
Oxygen Atoms

Reaction of oxygen atoms with 1,3-butadiene has been investigated at room temperature. It is found that it conforms to the general mechanism established previously for the analogous reactions of monoolefins. Only 1,2-addition occurs, and the addition products, butadiene monoxide and 3-butenal, possess excess energy when formed as a result of high heats of reaction. The pressure dependence of the formation of the addition products yields the values of the "lifetimes" of the initially produced "hot" molecules. The relative rate constants have been determined at 25 and 127 °C and from these the relative values of the Arrhenius parameters have been calculated.

Untersuchung konkurrierender Reaktionen in strömenden Kohlenwasserstoff-Gemischen / Investigation of Competing Reactions in Flowing Mixtures of Hydrocarbons

1974 ◽  
Vol 29 (4) ◽  
pp. 642-649 ◽  
Author(s):  
R. Laupert ◽  
G. von Bünau
Keyword(s):  
Rate Constants ◽  
Atomic Hydrogen ◽  
Relative Rate ◽  
Experimental Conditions ◽  
Kinetic Evaluation ◽  
Alkyl Radicals ◽  
Relative Rate Constants ◽  
Flow Apparatus ◽  
Competing Reactions

The reactions of atomic hydrogen with propene, butene-2, and trimethylethylene, and with mixtures of these olefins with ethylene have been studied using flow apparatus. It was found that under the experimental conditions intermediate alkyl radicals reacted practically only with atomic hydrogen. This made possible a kinetic evaluation of the results yielding numerical values of several relative rate constants of competing intermediate reactions.

Hydrogen Isotope Exchange in 2-Butanone. Further Measurements and Some Comments

1972 ◽  
Vol 50 (19) ◽  
pp. 3239-3241 ◽  
Author(s):  
R. A. Cox ◽  
J. W. Thorpe ◽  
J. Warkentin
Keyword(s):  
Acetic Acid ◽  
Temperature Dependence ◽  
Rate Constants ◽  
Hydrogen Isotope ◽  
Isotope Exchange ◽  
Relative Rate ◽  
Aqueous Media ◽  
Acetate Buffer ◽  
Isokinetic Temperature ◽  
Relative Rate Constants

The ratio of rate constants for exchange at the methylene and methyl positions of butanone, [Formula: see text], is shown to be near 1.69 in 1:1 acetic acid–acetate buffer; nearly twice the value (0.86) for deuterioxide catalysis at 54.8°. Methods of obtaining rate constants for acetate catalysis from composite rates (acetate and deuterioxide), or from rates in buffered media, are shown to be adequate for estimating rate ratios.Detailed temperature dependence of the relative rate constants for either system is not yet available but the effects are known to be small. For butanone enolizations the isokinetic temperature is in the neighborhood of 35°, when reaction is catalyzed by deuterioxide in aqueous media.

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