Phenol radical cations and phenoxyl radicals in electron transfer from the natural phenols sesamol, curcumin and trolox to the parent radical cations of 1‐chlorobutane

Abstract

AbstractThe free electron transfer from sesamol, curcumin and trolox to solvent (1‐chlorobutane) radical cations was studied. The solutes (ArOH) react with BuCl⋅+ at diffusion‐controlled rates (∼1010 dm3 mol−1 s−1) resulting, simultaneously, in phenol‐type radical cations (ArOH⋅+) and phenoxyl radicals (ArO⋅) with an ArOH⋅+/ArO⋅ ratio > 1;1. It was found that the kinetics are markedly affected by the different substituents on the aromatic ring of ArOH⋅+. The various ArOH⋅+ react with triethylamine with rate constants of ∼109 dm3 mol−1 s−1, whereas ethanol and dioxane are ineffective as cation scavengers. The effect of substituents on the electron transfer and the ArOH⋅+/ArO⋅ ratio is discussed on the basis of experimental data and quantum chemical calculations. Copyright © 2004 John Wiley & Sons, Ltd.