Results 291 to 300 of about 101,916 (337)
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Quantum effects and isotope effects in chemical kinetics
International Journal of Chemical Kinetics, 1979AbstractThe relations of quantum and kinetic isotope effects are investigated using the exact quantum corrections to the collision and activated complex theories. The latter are computed for the collinear three‐atomic reaction H2+ H → H + H2and the related isotopic reactions using realistic potential energy surfaces.
S. G. Christov, M. Parlapanski
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The kinetic isotope effect in the photochlorination of methane
Tetrahedron, 1963The kinetic isotope effect for the photochemically initiated chlorination of methane-d/sub 2/ was determined. The value is k /sub H//k/sub D/ = 12.1 at 0 deg C, and the variation with temperature is given by k/sub H//k/sub D/= 1.09 exp (1300/RT). The results are considered in terms of a semiempirical potential energy surface, and the general subject of
K.B. Wiberg, E.L. Motell
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Kinetic Isotope Effect in the Bromination of Dimethylaniline
Nature, 1959THE recent account by Shilov and Weinstein1 of a kinetic isotope effect in the iodination of some aromatic amines prompts us to report the observation of a similar effect in the bromination of dimethylaniline.
S. F. Mason, P. G. Farrell
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Influence of Substituents on Kinetic Isotope Effects
Journal of the American Chemical Society, 1996The E2 reactions of methyl- and fluoro-substituted ethyl chlorides with CH3-, NH2-, OH-, F-, SH-, and Cl- have been investigated at the MP2/6-31+G(d) level of theory for probing whether kinetic isotope effects are related to the geometry of the transition stucture.
Frank Jensen +2 more
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The kinetic isotope effect in the search for deuterated drugs
Drug News & Perspectives, 2010The kinetic isotope effect has long been exploited by physical organic chemists to study reaction mechanisms due to its effect on reaction rates when cleavage of a C-isotope bond is rate determining. Medicinal chemists have also used the deuterium kinetic isotope effect to slow the cytochrome P450 metabolism of the deuterated versions of drug ...
Liming Shao, Michael C Hewitt
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Kinetic Isotope Effects on Dehalogenations at an Aromatic Carbon
Environmental Science & Technology, 2008In order to interpret the observed isotopic fractionation it is necessaryto understand its relationship with the isotope effect(s) on steps that occur during the conversion of the initial reactant to the final product. We examine this relationship from the biochemical point of view and elaborate on the consequences of the assumptions that it is based ...
Rafał Kamiński +5 more
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Kinetic Isotope Effects on Chemical Reactions
2009This chapter describes a number of examples of kinetic isotope effects on chemical reactions of different types (simple gas phase reactions, SN2 and E reactions in solution and in the gas phase, α and β secondary isotope effects, etc.). These examples are used to illustrate many aspects of the measurement, interpretation, and theoretical calculation of
W. Alexander Van Hook +2 more
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The kinetic isotope effect in the rearrangement of neopentylchlorocarbene
Tetrahedron Letters, 1993Abstract The kinetic isotope effect for the 1,2∼H/1,2∼D shift of neopentylchlorocarbene ranges from 2.5–3.5.
Weiguo Liu +3 more
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Kinetic isotope effects calculated with the instanton method
Journal of Computational Chemistry, 2011AbstractThe ring‐opening reaction of the cyclopropylcarbinyl radical proceeds via heavy‐atom tunneling at low temperature. We used instanton theory to calculate tunneling rates and kinetic isotope effects with on‐the‐fly calculation of energies by density functional theory (B3LYP).
Judith B. Rommel +2 more
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6 Kinetic Isotope Effects in Enzymic Reactions
1970During the conversion of one molecule to another, new bonds are formed, old bonds broken, and other bonds experience changes, either transient or permanent, in their hybridization. Isotopic substitution can have a profound influence on the energetics of these bonding changes.
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