Secondary a-deuterium kinetic isotope effect

Secondary a-deuterium kinetic isotope effect proved to be very useful in distinguishing between the organic reaction mechanisms of dissociative (S]sj 1) and associative (Sj 2) types. A. Streitwieser, Jr. et al. and K. C. Westa- 

INFLUENCE OF TUNNELING ON THE PRIMARY AND SECONDARY KINETIC ISOTOPE EFFECTS 

the wave function in front of the potential barrier is  

The reflected wave appears in front of the potential barrier, part of the wave function corresponding to Behind the potential barrier, the wave 

The rapidly established equilibrium in proton transfer reactions shows the proton s ability of tunneling. 

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What concerns us here are three topics addressing the fates of bromonium ions in solution and details of the mechanism for the addition reaction. In what follows, we will discuss the x-ray structure of the world s only known stable bromonium ion, that of adamantylideneadamantane, (Ad-Ad, 1) and show that it is capable of an extremely rapid degenerate transfer of Br+ in solution to an acceptor olefin. Second, we will discuss the use of secondary a-deuterium kinetic isotope effects (DKie) in mechanistic studies of the addition of Br2 to various deuterated cyclohexenes 2,2. Finally, we will explore the possibility of whether a bromonium ion, generated in solution from the solvolysis of traAU -2-bromo-l-[(trifluoromethanesulfonyl)oxy]cyclohexane 4, can be captured by Br on the Br+ of the bromonium ion, thereby generating olefin and Br2. This process would be... 

Secondary a-deuterium kinetic isotope effects (KIEs) have been widely used to determine the mechanism of SN reactions and to elucidate the structure of their transition states (Shiner, 1970a Westaway, 1987a). Some of the significant studies illustrating these principles are presented in this section. 

This solvation rule for 5n2 reactions can be useful in predicting the influence of a change in solvent on the structure of activated complexes. It is in agreement with studies involving leaving group heavy atom and secondary a-deuterium kinetic isotope effects, as well as theoretical calculations of solvent effects on transition-state structures. Possible limitations of this solvation rule have been discussed see [498] and relevant references cited therein. 

For a theoretical study of the relationship between the structure of Sn2 transition states cind secondary a-deuterium kinetic isotope effects, see Poirier, R. A. Wang, Y. Westaway, K. C. /. Am. 

Secondary a-deuterium kinetic isotope effect and tunneling... 

In reactions where the secondary a-deuterium kinetic isotope effect (a-D KIE) was substantial (20% per one D, or more) the mechanism was found to be dissociative (Sj.jl), with the transition state similar to the carbonium ion. Small a-KIE were found in nucleophilic substitutions of the associative type (8 2). In these substitutions amounted to about 1.00 (no isotope... 

SECONDARY a-DEUTERIUM KINETIC ISOTOPE EFFECT AND THE STRUCTURE OF FERROCENYLMETHYL CARBOCATION TYPE TRANSITION STATE... 

High secondary a-deuterium kinetic isotope effects for the primary carhon-oxygen cleavage in formolysis and acetolysis of dideuterioferrocenylmethyl henzoate... 

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