Oxidation of Hydrocarbons. VII. Kinetics of the Oxidation of Naphthalenes by Ruthenium Tetroxide

1975 ◽  
Vol 53 (19) ◽  
pp. 2865-2868 ◽  
Author(s):  
Udo A. Spitzer ◽  
Donald G. Lee
Keyword(s):  
Isotope Effect ◽  
Bond Cleavage ◽  
Initial Reaction ◽  
Second Order Reaction ◽  
Deuterium Isotope Effect ◽  
Ruthenium Tetroxide ◽  
First Order ◽  
Oxidation Of Hydrocarbons ◽  
Inverse Isotope Effect ◽  
Kinetics Of

The kinetics of the oxidation of naphthalene by ruthenium tetroxide have been investigated. When the reaction was monitored using an absorption band at 385 nm it was possible to detect two processes; the first, a rapid second-order reaction which yielded a ruthenium(VI) moiety, was followed by a much slower first-order decomposition of this intermediate. The initial reaction exhibited an inverse isotope effect when naphthalene-d8 was used as a substrate and was accelerated by the introduction of electron donating substituents. The decomposition of the intermediate was not sensitive to the presence of substituents, but involved carbon–hydrogen bond cleavage as indicated by the occurrence of a primary deuterium isotope effect.

The kinetics of proton and deuteron transfer from 4-nitrophenylnitromethane and l-(4-nitrophenyl)-l-nitroethane to 2,7-dimethoxy-l,8-bis(dimethylamino)naphthalene in acetonitrile solvent

1981 ◽  
Vol 59 (21) ◽  
pp. 3034-3038 ◽  
Author(s):  
Kenneth T. Leffek ◽  
Przemyslaw Pruszynski
Keyword(s):  
Isotope Effect ◽  
Reaction Rate ◽  
Significant Contribution ◽  
Reaction Parameters ◽  
Deuterium Isotope Effect ◽  
First Order ◽  
Enthalpy Of Activation ◽  
Deuteron Transfer ◽  
Slow Dissociation ◽  
Kinetics Of

4-Nitrophenylnitromethane reacts with 2,7-dimethoxy-1,8-bis(dimethylamino)naphthalene in acetonitrile in a bimolecular proton transfer, which shows a primary deuterium isotope effect, kH/kD = 12.2 at 25 °C. The large isotope effect on the enthalpy of activation, (ΔHD≠ – ΔHH≠) = 4.6 ± 0.3 kcal mol−1 is consistent with a significant contribution of proton tunnelling to the reaction rate of the protium substrate.The analogous reaction of 1-(4-nitrophenyl)-1-nitroethane with the same base in acetonitrile gives contrasting kinetics and reaction parameters. The reaction is first order, showing no dependence on base concentration. While the isotope effect kH/kD = 9.3 at 25 °C, the enthalpy of activation difference (ΔHD≠ – ΔHH≠) is only 0.5 ± 0.1 kcal mol−1. It is concluded that the 1-(4-nitrophenyl)-1-nitroethane undergoes a slow dissociation, with a very small dissociation constant, followed by a fast association with the base to yield the carbanion ion-pair.

THE KINETICS OF THE INHIBITED AUTOXIDATION OF TETRALIN

1964 ◽  
Vol 42 (10) ◽  
pp. 2324-2333 ◽  
Author(s):  
J. A. Howard ◽  
K. U. Ingold
Keyword(s):  
Isotope Effect ◽  
Chain Transfer ◽  
Square Root ◽  
Deuterium Isotope Effect ◽  
First Order ◽  
Oxidation Rates ◽  
First Order Kinetics ◽  
A Value ◽  
Root Relation ◽  
Kinetics Of

The kinetics of the inhibition of the autoxidation of tetralin by 2,6-di-t-butyl-4-methylphenol, phenol, and 4-methoxyphenol have been investigated at 65 °C. The highly hindered 2,6-di-t-butyl-4-methylphenol follows simple first order kinetics and exhibits a normal deuterium isotope effect (kH/kD = 10). The kinetics with phenol are complicated by the fact that the phenoxy radical can abstract a hydrogen atom from both tetralin and its hydroperoxide. This leads to oxidation rates which are inversely proportional to the square root of the phenol concentration. The deuterium isotope effect has about the value to be expected in view of this square root relation. The kinetics with 4-methoxyphenol result from chain transfer and from chain termination by the coupling of 4-methoxyphenoxy radicals. The isotope effect varies between zero and a value that approaches the upper limit of about 10 at low inhibitor concentrations.

scholarly journals The alcoholysis of 1,2,2-trimethylpropyl-methylfluorophosphonate

2000 ◽  
Vol 65 (12) ◽  
pp. 857-866
Author(s):  
Mladjen Micevic ◽  
Slobodan Petrovic
Keyword(s):  
Kinetic Data ◽  
Reaction Rate ◽  
Frequency Factor ◽  
Reaction Rate Constant ◽  
Order Reaction ◽  
Activation Entropy ◽  
Second Order Reaction ◽  
Third Order ◽  
First Order ◽  
Kinetics Of

The alcoholysis of 1,2,2-trimethylpropyl-methylfluorophosphonate (soman) was examined with a series of alkoxides and in corresponding alcohols: methanol, ethanol, 1-propanol, 2-propanol, 2-methoxyethanol and 2-ethoxyethanol. Soman reacts with the used alkoxides in a second order reaction, first order in each reactant. The kinetics of the reaction between 1,2,2-trimethylpropyl-methylfluorophosphonate and ethanol in the presence of diethylenetriamine was also examined. A third order reaction rate constant was calculated, first order in each reactant. The activation energy, frequency factor and activation entropy were determined on the basis of the kinetic data.

Studies in the Vulcanization of Rubber. III—Kinetics of Vulcanization of Rubber with Sulfur and Selenium

1930 ◽  
Vol 3 (4) ◽  
pp. 650-659
Author(s):  
John T. Blake
Keyword(s):  
Molecular Weight ◽  
Order Reaction ◽  
Order Equation ◽  
Second Order Reaction ◽  
Experimental Conditions ◽  
Mathematical Basis ◽  
First Order ◽  
Kinetics Of ◽  
Kinetics Of Vulcanization

Abstract A procedure for the determination of combined selenium in rubber has been evolved. The rate of combination of selenium and rubber has been ascertained under certain conditions and shown to follow a first-order equation. A minimum value for the molecular weight of rubber has been estimated. The formation of hard rubber under chosen experimental conditions has been put on a mathematical basis and has been shown to follow a second-order reaction. The soft- and hard-rubber reactions have been shown qualitatively to be successive reactions and the function of accelerators has been discussed. The theory explains the anomalous results obtained by previous investigators.

KINETIC STUDIES ON THE HYDROLYSIS OF BENZOYLCHOLINE BY HUMAN SERUM CHOLINESTERASE

1956 ◽  
Vol 34 (1) ◽  
pp. 637-653 ◽  
Author(s):  
W. Kalow ◽  
K. Genest ◽  
N. Staron
Keyword(s):  
Kinetic Studies ◽  
Reaction Rates ◽  
Serum Cholinesterase ◽  
Initial Reaction ◽  
Ultraviolet Spectrophotometry ◽  
First Order ◽  
Low Concentrations ◽  
Kinetics Of ◽  
Hydrolysis Of ◽  
Substrate Concentrations

Benzoylcholine stands out from other known substrates of serum cholinesterase because of its high apparent affinity for this enzyme combined with a rapid rate of destruction. The reaction kinetics of the hydrolysis of benzoylcholine can be studied by ultraviolet spectrophotometry, since the absorbance decreases in proportion to the concentration of substrate. Kinetic data obtained by measuring initial reaction rates, and by analyzing continuous hydrolysis curves, are the same within the range of experimental error. The enzymatic data are compatible with the assumption that in the presence of high substrate concentrations a complex consisting of esterase and two substrate molecules is formed. This complex is hydrolyzed more slowly than the complex containing one molecule of substrate which is formed at low concentrations of benzoylcholine. Alkaline hydrolysis of benzoylcholine follows the kinetics of a first order reaction.

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