γ-Radiolysis of Aqueous Benzothiophene Solutions

Article abstract of DOI:10.1021/j150614a029

γ-Radiolysis of aqueous benzothiophene solutions saturated with N2O has been studied.In the absence of other reagents, the only products detected are 2- and 3-hydroxybenzothiophene and their corresponding lactonic and ketonic tautomers and a small amount of dimeric species.In the presence of potassium hexacyanoferrate or sodium hydroxide, however, products attributable to hydroxylation at all six available carbon sites are detected and dimer formation is reduced.Analysis of the experimental data suggests that both benzothiophene and its hydroxylation products are efficient scavengers for the radiation-produced OH radicals and that the initial yield of hydroxylation products is equal to that of hydroxyl radicals.Consistent with the electrophilic characteristics of the OH radical, k(OH+C8H6S):k(OH+C8H5SOH)=0.5+/-0.1.All six available carbon sites are capable of forming OH adducts, but the radicals formed by addition to the 4, 5, 6, and 7 positions tend to revert to the original compound or its ion in a neutral or acidic medium.In the case of the adducts formed by addition to the thiophene ring, on the other hand, the 3 position is seen to be favored, possibly as the result of the preservation of the aromatic benzene resonance structure.