Thus, the electron transfer mechanism can account for rates which are higher than the rate one might expect by simply correlating rate with one solvent property. Foti et al. also discovered this fast electron-transfer reaction between phenols and DPPH . While hydrogen atom transfer was dominant in nonpolar solvents most of the time, electron transfer still occurred if the radical was strongly oxidizing, as with Cl 3 COO•. Reactions proceeding via the electron-transfer mechanism should be faster in polar solvents.