Additivity of contributions to secondary deuterium kinetic isotope effects and their Arrhenius preexponential factors. Method of fitting model calculations to experimental data

1973 ◽  
Vol 95 (5) ◽  
pp. 1355-1365 ◽  
Author(s):  
Mary E. Schnieder ◽  
Marvin J. Stern
Keyword(s):  
Experimental Data ◽  
Isotope Effects ◽  
Kinetic Isotope Effects ◽  
Model Calculations ◽  
Kinetic Isotope ◽  
Fitting Model

Model Calculations of Kinetic Isotope Effects in Nucleophilic Substitution Reactions

1974 ◽  
Vol 52 (6) ◽  
pp. 903-909 ◽  
Author(s):  
Jan Bron
Keyword(s):  
Transition State ◽  
Isotope Effects ◽  
Benzyl Bromide ◽  
Kinetic Isotope Effects ◽  
Substitution Reactions ◽  
Model Calculations ◽  
Kinetic Isotope ◽  
Proposed Model ◽  
Standard Reaction ◽  
Deuterium Isotope Effects

The results of calculations indicate that a previously proposed model for the transition state in "borderline" substitution reactions can be generalized and, as a result, the observed differences in the carbon-13 and deuterium isotope effects of SN1, SN2, and "borderline" reactions rationalized. Although the conclusions may apply more generally, the standard reaction investigated is the solvolysis of benzyl bromide. The importance of resonance interaction with the phenyl ring, the significance of the product- or reactant-like character of the transition state, and the influence of the magnitude of force constants in determining isotope effects are examined. The temperature dependence of kinetic isotope effects in solvolysis is also investigated.

scholarly journals Inverse kinetic isotope effects in the charge transfer reactions of ammonia with rare gas ions

2021 ◽  
Author(s):  
Andriana Tsikritea ◽  
Kibum Park ◽  
Paul Bertier ◽  
Jérôme Loreau ◽  
Timothy P Softley ◽  
...  
Keyword(s):  
Experimental Data ◽  
Charge Transfer ◽  
Isotope Effects ◽  
Kinetic Isotope Effects ◽  
Data Models ◽  
Transfer Reactions ◽  
Rare Gas ◽  
Complex Chemical ◽  
Kinetic Isotope ◽  
Charge Transfer Reactions

In the absence of experimental data, models of complex chemical environments rely on predicted reaction properties. Astrochemistry models, for example, typically adopt variants of capture theory to estimate the reactivity...

Calculation of kinetic isotope effects in formation of carbon dioxide from a diester of oxalic acid

1967 ◽  
Vol 45 (24) ◽  
pp. 3045-3047 ◽  
Author(s):  
J. Warkentin ◽  
D. M. Singleton
Keyword(s):  
Experimental Data ◽  
Carbon Dioxide ◽  
Oxalic Acid ◽  
Isotope Effects ◽  
Kinetic Isotope Effects ◽  
Isotopic Abundance ◽  
Partial Decomposition ◽  
Kinetic Isotope

Equations for the calculation of isotope effects (k12/k13 and k16/k18) in the concerted twobond thermolysis of oxalates are presented. The equations are developed for material of low isotopic abundance such that the presence of doubly labelled molecules can be ignored. No assumption is made about the distribution of 18O between the carbonyl and ether functions, other than that the distribution is known. The experimental data required are the ratios CO246/CO244, and CO245/CO244, corrected for the presence of 17O and 14C, in the CO2 obtained from partial decomposition and in the CO2 from total decomposition and the fractional extent of reaction.

Model calculations of isotope effects. IX. Origin of large hydrogen and carbon isotope effects in the deprotonation of 2-nitropropane by pyridine bases

1983 ◽  
Vol 36 (8) ◽  
pp. 1521
Author(s):  
DJ McLennan
Keyword(s):  
Transition State ◽  
Isotope Effects ◽  
Kinetic Isotope Effects ◽  
Bond Orders ◽  
Model Calculations ◽  
Kinetic Isotope ◽  
Pyridine Bases ◽  
State Models ◽  
Experimental Findings ◽  
Large Primary

The abnormally large primary hydrogen and carbon kinetic isotope effects found in the deprotonation of 2-nitropropane by hindered pyridine bases are investigated by means of model calculations. Transition-state models have been varied between tight and loose extremes, and between carbanion-like and nitronate-like structures. The only models that reproduce the experimental findings are those in which the sum of the bond orders to the transferring proton is less than unity (loose transition states) and which are subject to tunnelling corrections.

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