An ab initio study of S(N)2 reactivity at C6 in hexopyranose derivatives. I. Influence of dipole-dipole interactions in the transition structure.
It is widely accepted that dipole-dipole interactions in the S(N)2 transition structure can play a dominant role in determining reaction rates. A model of this type was proposed some years ago to explain the remarkably low reactivity of galactopyranose-6-O-sulfonates toward S(N)2 displacement, and similar arguments have recently been restated in the context of gas-phase reactions. In this paper, we present ab initio calculations (B3LYP/6-31+G(d,p)) on model structures and an analysis of charge densities using the theory of atoms in molecules. We find that the maximum possible impact of local dipole-dipole interactions is insufficient to account for the observed reactivity differences.
Dawes
Richard
R
Department of Chemistry, University of Manitoba, Winnipeg, Manitoba R3T 2N2, Canada.
Gough
Kathleen M
KM
Hultin
Philip G
PG
D002241:Carbohydrates / Q000737:chemistry*; D002244:Carbon / Q000737:chemistry*; D003198:Computer Simulation; D008958:Models, Molecular; D015394:Molecular Structure
D002241:Carbohydrates; D002244:Carbon