title: Rate and driving force for protonation of aryl radical anions in ethanol.
abstract: Aryl radical anions created in liquid alcohols decay on the microsecond time scale by transfer of protons from the solvent. This paper reports a 4.5 decade range of rate constants for proton transfer from a single weak acid, ethanol, to a series of unsubstituted aryl radical anions, Ar-*. The rate constants correlate with free energy change, DeltaG(o), despite wide variations in the two factors that contribute to DeltaG(o): (a) the reduction potentials of the aryls and (b) the Ar-H* bond strengths in the product radicals. For aryl radical anions containing CH2OH substituents, such as 2,2'-biphenyldimethanol*- which is protonated with a rate constant of 3x10(9) s(-1), the faster rates do not fit well in the free energy correlation, suggesting a change in mechanism.
authors.affiliation: Chemistry Department, Brookhaven National Laboratory, Upton, New York 11973, USA.
authors.forename: Alison M
authors.initials: AM
authors.lastname: Funston
authors.forename: Sergei V
authors.initials: SV
authors.lastname: Lymar
authors.forename: Barbara
authors.initials: B
authors.lastname: Saunders-Price
authors.forename: Gidon
authors.initials: G
authors.lastname: Czapski
authors.forename: John R
authors.initials: JR
authors.lastname: Miller