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

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.