HYDROGEN-BONDING EFFECTS IN THE EPOXIDATION OF PROPENOL WITH DIOXIRANES - A DFT COMPUTATIONAL STUDY

Potential energy surfaces for the epoxidations of 2-propen-1-ol with d ioxirane (DHD) and dimethyldioxirane (DMD) were investigated at the B3 LYP/6-31G level. Seven transition structures (TSs) were located for t he reaction of DHD. The four chemically more significant TSs were loca ted also for the reaction of DMD. Geometries and energies of two of th em clearly demonstrate that stabilizing hydrogen bonding interactions can be at work and that they involve both the dioxirane oxygens. Calcu lations indicate that the electron attracting effect of the allylic hy droxy group has a relatively small rate retarding effect. Calculations predict higher reactivity for propenol with respect to propene reacti on in gas phase but introduction of electrostatic solvation effects (a cetone, Tomasi model) leads to reactivity reversal in substantial agre ement with experimental data. (C) 1998 Elsevier Science Ltd. All right s reserved.