For the mechanism of decarboxylation reactions, all textbooks show electrons moving from the πC=O bond. However, the most electron-donating bond orbital in the carbonyl group is expected to be the lone pair(s) on the oxygen. Thus, orbital theory with delocalization from a lone pair may be more appropriate than delocalization from the πC=O orbital. We confirmed our idea by theoretical calculations. In the TS, if we use 2-substituted

A new picture of the reaction mechanism of peracid epoxidation of olefins is proposed from the perspective of bond interaction. In contrast to the mechanism from the perspective of electronic theory, which includes the movement of an electron from the -bond to the negatively charged oxygen atom, the olefin is initially protonated and then migrates to the oxygen atom.