Kinetics of Coordinate Bond Formation. IV. Kinetic Isotope Effect in the Reaction NH3+BF3

1961 ◽  
Vol 34 (3) ◽  
pp. 712-714 ◽  
Author(s):  
G. B. Kistiakowsky ◽  
C. E. Klots
Keyword(s):  
Isotope Effect ◽  
Kinetic Isotope Effect ◽  
Bond Formation ◽  
Kinetic Isotope ◽  
Coordinate Bond ◽  
Kinetics Of

Atmospheric chemistry of ethers, esters, and alcohols on the lifetimes, temperature dependence, and kinetic isotope effect: an example of CF3CX2CX2CX2OX with OX reactions (X = H, D)

RSC Advances ◽  
2016 ◽  
Vol 6 (42) ◽  
pp. 36096-36108 ◽  
Author(s):  
Feng-Yang Bai ◽  
Xu Wang ◽  
Yan-Qiu Sun ◽  
Rong-Shun Wang ◽  
Xiu-Mei Pan
Keyword(s):  
Temperature Dependence ◽  
Isotope Effect ◽  
Atmospheric Chemistry ◽  
Theoretical Basis ◽  
Kinetic Isotope Effect ◽  
Kinetic Isotope ◽  
Kinetics Of ◽  
Sound Theoretical Basis

Mechanisms and kinetics of the reaction of CF3CX2CX2CX2OX with OX (X= H, D) radical are investigated on a sound theoretical basis.

Allosteric control of pyrimidine transport in Hymenolepis diminuta: an unusual kinetic isotope effect

Parasitology ◽  
1983 ◽  
Vol 87 (2) ◽  
pp. 289-293 ◽  
Author(s):  
G. L. Uglem ◽  
R. K. Dupre ◽  
J. P. Harley
Keyword(s):  
Isotope Effect ◽  
Kinetic Isotope Effect ◽  
Pyrimidine Ring ◽  
Hymenolepis Diminuta ◽  
Absorption Kinetics ◽  
Allosteric Control ◽  
Kinetic Isotope ◽  
Sigmoidal Kinetics ◽  
Kinetics Of ◽  
Initial Uptake

SUMMARYA thymine–uracil transport system is present in the plasma membrane brush-border of the tapeworm, Hymenolepis diminuta. The relation between initial uptake and substrate concentration of either thymine or uracil was sigmoidal when 2-14C-labelled substrates were used. In contrast, absorption kinetics of methy 1-14C- and 3H-labelled substrates were hyperbolic. Since there was no metabolism of the labelled substrates during the incubation period, these differences indicate that the sigmoidal kinetics of pyrimidine transport in this organism is an isotope effect associated with the presence of the 14C label at the 2 position in the pyrimidine ring.

Acid and Base Catalysis in the Oxidation of 6,7,8-Trimethyllumazine. II. Kinetics and Mechanism

1974 ◽  
Vol 52 (23) ◽  
pp. 3884-3894 ◽  
Author(s):  
Ross Stewart ◽  
Kiyotaka Oyama
Keyword(s):  
Isotope Effect ◽  
Kinetic Isotope Effect ◽  
Base Catalysis ◽  
Methyl Group ◽  
General Base ◽  
Kinetic Isotope ◽  
Conjugate Acid ◽  
Acid And Base ◽  
Rate Plot ◽  
Kinetics Of

The kinetics of the oxidation of 6,7,8-trimethyllumazine, 1, by permanganate in aqueous solution is examined. The pH–rate plot shows a minimum at pH 3.5 and there is catalysis by buffers. Above pH 3.5 the 7-keto compound, 5, is produced by a general base catalyzed route the rate of which is identical to that of the reaction that causes exchange at the 7-methyl group. The kinetic isotope effect for oxidation of the 7-CD3 compound is 6.89 at 31.4°.Below pH 3.5 scission of the pyrazine ring occurs, there is a small isotope effect, and the rate is somewhat faster than that observed for exchange of the 7-methyl group. There appear to be three routes leading to product; one, a permanganate-independent reaction catalyzed by general acids, a second which is also permanganate independent and involves hydration of the substrate, and a third which is permanganate dependent and involves attack by permanganate on the conjugate acid of the substrate.The utility of oxidation as a means of locating hydration sites in heterocyclic compounds is discussed and some comments are made on the mechanism of the enzymic oxidation of the ribityl analog of 1.

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