title: Abnormal solvent effects on hydrogen atom abstractions. 1. The reactions of phenols with 2,2-diphenyl-1-picrylhydrazyl (dpph*) in alcohols.
abstract: Rate constants, k(ArOH/dpph*)(S), for hydrogen atom abstraction from 13 hindered and nonhindered phenols by the diphenylpicrylhydrazyl radical, dpph*, have been determined in n-heptane and a number of alcoholic and nonalcoholic, hydrogen-bond accepting solvents. Abnormally enhanced k(ArOH/dpph*)(S) values of have been observed in alcohols. It is proposed that this is due to partial ionization of the phenols and a very fast electron transfer from phenoxide anion to dpph*. The popular assessment of the antioxidant activities of phenols with dpph* in alcohol solvents will generally lead to an overestimation of their activities.
authors.affiliation: National Research Council, 100 Sussex Drive, Ottawa, Ontario, Canada, K1A 0R6. grzegorz.litwinienko@nrc.ca
authors.forename: Grzegorz
authors.initials: G
authors.lastname: Litwinienko
authors.forename: K U
authors.initials: KU
authors.lastname: Ingold