Reactivity and selectivity of reactions of small radicals with a multifunctional heterocyclic molecule: 3-(mercaptoethyl)chinazoline-2,4-(1H,3H)dione

Using pulse radiolysis, we studied the reactions of small radicals (e(aq)(- ), OH., N-3(.), and (CH2OH)-C-.) with 3-(mercaptoethyl)chinazoline-2,4-(1H, 3H) in aqueous solution. Whereas the solvated electron adds selectively to the carbonyl group near the aromatic moiety, the hydroxyl radical reacts by addition to the aromatic ring as well as by H abstraction at >N(l)H and -S H groups. Also, azide radicals nonspecifically oxidize the aromatic ring, t he thiol group, or the thiolate anion and the amine group at N-(l), as iden tified by subsequent radical products. In contrast, hydroxymethyl radicals (derived from methanol) abstract hydrogen selectively at the thiol group. T he thiyl radical formed was used to study the kinetics of H abstraction in the bisallylic positions of linolenic acid. Product transient identificatio n was performed by kinetic analysis as well as by comparison with reactions of molecules with structures less complex than that of the title compound, exhibiting relevant functional groups.