How vitamin E scavenges DPPH radicals in polar protic media

Abstract

Although three mechanisms, i.e., one-step H-atom transfer (HAT), sequential proton-loss–electron-transfer (SPLET) and stepwise electron-transfer–proton-transfer (ET–PT), have been proposed to elucidate the 1,1-diphenyl-2-picrylhydrazyl radical (DPPH˙) scavenging of 2,2,5,7,8-pentamethyl-6-hydroxychroman (PMHC), a vitamin E model, in methanol, our theoretical analysis indicates that the former two processes are more probable than the latter one.