Radiation Chemistry of Nitrogen and Sulfur Heterocyclics

The gamma radiolysis of nitrogen and sulfur heterocyclics having one or more nitrogen or sulfur atoms in five- and six-membered rings was studied. G values are given for the major gaseous products identified by gas chromatography for the radiolyses of pyrrole, pyrazole, imidazole, 1,2,4-triazole, tetrazole, pyrazine, pyrimidine, 1,3,5-triazine, benzotriazole, thiazole, isothiazole, and thiophene. The principal gaseous product formed during the γ-radiation of five- and six-membered nitrogen heterocyclics was hydrogen except that compounds having two adjacent nitrogen atoms in the ring produced large amounts of nitrogen and other gaseous products. When the N atoms are separated by carbon atoms, no nitrogen gas is produced and the G values for gas production are very low. Thiophene has greater stability to radiation than pyrrole as far as gas production is concerned. However, the introduction of a second heteroatom (nitrogen in the case of thiazole and isothiazole) in the five-membered ring containing sulfur (thiophene) does not change the radiosensitivity of the molecule. The nature of the free radicals formed by the irradiation of tetrazole at low doses (<tex-math>$1\times 10^{18}\ {\rm eV}/{\rm g}$</tex-math>) was studied by esr. Radical species of at least two types are produced.