Anthralin: Primary Products of Its Redox Reactions

One-electron reduction significantly enhances the ability of anthralin, 1, to act as a hydrogen atom donor.
On annealing of an MTHF glass in which the radical anion of anthralin, 1•-, is generated radiolytically,
this species decays mainly by loss of H• to give the anthralyl anion, 2-. On the other hand, radicals
formed on radiolysis of matrices that are suitable for the generation of radical anions or cations are
capable to abstract H• from anthralin to give the anthralyl radical, 2•. Both 2- and 2• are obtained
simultaneously by mesolytic cleavage of the radical anion of the anthralin dimer. Contrary to general
assumptions, the anthralyl radical is found to be much more reactive toward oxygen than the anion. All
intermediates are characterized spectroscopically and by reference to quantum chemical calculations.
Attempts to generate the radical cation of anthralin by X-irradiation of an Ar matrix containing anthralin
led also to significant formation of its radical anion, i.e., anthralin acts apparently as an efficient electron
trap in such experiments.