Reactions of pyrazine radical anions in solution. I. Study of the kinetics of the dimerization of pyrazine radical anions

Abstract

The radical anions of pyrazine (pz-.) have been prepared at 294'K by reducing pyrazine (pz) with metallic potassium in 1,2-dimethoxyethane (dme). The resulting reactions of the radical anions are postulat'ed as being described by the equations: The e.s.r, and electronic absorption spectra of all pertinent species were recorded and examined. The kinetics of reaction (1) have been investigated in the dark as well as in light and values of the rate constants have been determined. I n light, reaction (1) did not conform strictly to second-order kinetics and this may be explained by an interaction of pyrazine with dme. The dimer dianion species (-pz-pz-, 2K7) was found to be stable in the dark but decayed slowly in light. This decay was found to exhibit first-order kmetics.