Protonation of the reduced species in irradiated acetonitrile

The rate of the reaction of the radiolytically produced reduced species in acetonitrile with various protic solutes (alcohols and water) was measured by the competition method and by directly following the rate of disappearance of the reduced species in pulse radiolytic experiments. The rate constants thus obtained were correlated with the pK_a of the protic additives. This correlation leads to the conclusion that the reaction occurs via a proton transfer. Temperature effect studies on the rate of this reaction lead to the conclusion that the reactive species is the dimer anion radical (CH₃CN)^-₂.