TRANSIENTS FORMED DURING REDUCTION OF POLYNUCLEAR AROMATICS - A PULSE-RADIOLYSIS STUDY

Pulse radiolysis studies of the reduction of polynuclear aromatic hydr ocarbons naphthalene, anthracene, pyrene and pentacene (ArH) with solv ated electron and H atom have been carried out on the nanosecond time scale, using 7 MeV electron pulses in polar organic solvents, both pro tic and aprotic. Kinetic results of reactions of ArH with e-solv show high reactivity (k ca. 10(10) dm3 mol-1 s-1) to form the respective ra dical anions (ArH.-), with increasing yields in the presence of primar y low molecular weight aliphatic amines and alcohols. In an attempt to follow the individual radical anion reactivity in these solvents, the ir decay to form the respective monohydro radicals (ArH2.) were observ ed. The measured pseudo-first-order formation rate constants of the re spective ArH2. (k(f) ca. 10(5) to 10(3) s-1) indicate that, in the pre sence of dissolved alkali metal in THF and amines/ammonia, as in the B irch synthesis, the reduction of these hydrocarbons follows this mecha nism.