Calculations of Substituent and Solvent Effects on the Kinetic Isotope Effects of Menshutkin Reactions

2003 ◽  
Vol 68 (21) ◽  
pp. 8232-8235 ◽  
Author(s):  
Emilia Owczarek ◽  
Wojciech Kwiatkowski ◽  
Michał Lemieszewski ◽  
Adam Mazur ◽  
Michał Rostkowski ◽  
...  
Keyword(s):  
Solvent Effects ◽  
Isotope Effects ◽  
Kinetic Isotope Effects ◽  
Kinetic Isotope

Solvent effects on SN2 transition state structure. II: The effect of ion pairing on the solvent effect on transition state structure

1989 ◽  
Vol 67 (2) ◽  
pp. 345-349 ◽  
Author(s):  
Kenneth Charles West Away ◽  
Zhu-Gen Lai
Keyword(s):  
Transition State ◽  
Solvent Effects ◽  
Isotope Effects ◽  
Ion Pairs ◽  
Kinetic Isotope Effects ◽  
Ion Pair ◽  
State Structure ◽  
Butyl Chloride ◽  
Transition State Structure ◽  
Kinetic Isotope

Identical secondary α-deuterium kinetic isotope effects (transition state structures) in the SN2 reaction between n-butyl chloride and a free thiophenoxide ion in aprotic and protic solvents confirm the validity of the Solvation Rule for SN2 Reactions. These isotope effects also suggest that hydrogen bonding from the solvent to the developing chloride ion in the SN2 transition state does not have a marked effect on the magnitude of the chlorine (leaving group) kinetic isotope effects. Unlike the free ion reactions, the secondary α-deuterium kinetic isotope effect (transition state structure) for the SN2 reaction between n-butyl chloride and the solvent-separated sodium thiophenoxide ion pair complex is strongly solvent dependent. These completely different responses to a change in solvent are rationalized by an extension to the Solvation Rule for SN2 Reactions. Finally, the loosest transition state in the reactions with the solvent-separated ion pair complex is found in the solvent with the smallest dielectric constant. Keywords: ion pairs, transition state, solvent effects, nucleophilic substitution, isotope effects.

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