A simple, self‐consistent electrostatic model for quantitative prediction of the activation energies of four‐center reactions. II.*

Abstract

A simple electrostatic model of point dipoles is used which permits direct calculation of the activation energies for the addition of the molecules H₂O, H₂S, H₃N, and H₃P to olefins. These calculated values agree with the known experimental data to within ±2 kcal/mole on the average. It was found that the best fit could be obtained with a polar transition state that corresponded to a reduction in bond order from 1 to ½ for the bond‐breaking coordinates and an increase in bond order from 0 to 0.18 for the bond‐forming coordinates. The replacement of a hydrogen atom of the species H₂O, H₂S, H₃N, or H₃P by a polarizable methyl group is expected to stabilize the charge on the central atoms. The following stabilization energies for the pairs H₂OCH₃OH, H₂SCH₃SH, H₃NCH₃NH₂, H₃PCH₃PH₂ were calculated: −4.8 kcal/mole, −0.7 kcal/mole, −1.9 kcal/mole, −0.8 kcal/mole, respectively.