Deuterium isotope effect on the kinetics of aquation of dichloro(β,β′,β″-triaminotriethylamine)cobalt(III) ion

1972 ◽  
Vol 6 ◽  
pp. 401-402 ◽  
Author(s):  
Sybil G. Zipp ◽  
Stanley K. Madan
Keyword(s):  
Isotope Effect ◽  
Deuterium Isotope Effect ◽  
Kinetics Of

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.

Kinetics of the hydrolysis of thiochloroformate esters in pure water

1970 ◽  
Vol 48 (4) ◽  
pp. 522-527 ◽  
Author(s):  
A. Queen ◽  
T. A. Nour ◽  
M. N. Paddon-Row ◽  
K. Preston
Keyword(s):  
Isotope Effect ◽  
Structural Changes ◽  
Pure Water ◽  
Activation Parameters ◽  
Deuterium Isotope Effect ◽  
Hydro Carbon ◽  
Electron Donation ◽  
Kinetics Of ◽  
Hydrolysis Of

The effects of structural changes on the rates of hydrolysis of a series of thiochloroformate esters in water have been investigated. The reactivity is enhanced by increased electron donation by the hydro carbon group. These results, the activation parameters for the hydrolysis of methyl thiochloroformate and the solvent deuterium isotope effect, are shown to be consistent with the operation of the SN1 mechanism.

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.

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