Species with multicenter H-bonding in isomerization of peracetic acid into corresponding dioxirane

The ab initio quantum chemical methods are applied to investigate mutual transformations of peracetic acid and 3-methyl-1,2-dioxirane-3-ol. It is for the first time found that the peroxycarboxylic group proton is bonded simultaneously to three oxygen atoms as in both tautomers as well in the activated complex. Furthermore, it is found that the suitable tautomeric transition 'coordinate' has a complex character and can't be reduced to simple proton mode. Both peculiarities are substantial for tautomeric transition mechanism and make doubtful the adopted mechanism of olefin epoxidation since for both reactions the proton transfer stage is common.