Effects of Temperature and Added Hexachloroethane on the Radiolyses of Carbon Tetrachloride and Chloroform

Abstract

HC1 yields from irradiated chloroform are, for doses a t least as high as 1.3 X 1021 e.v. per gram, greater a t 70 i 4" than at 20". The initial G-value at the higher temperature is 31 compared wit! an average of 11.9 at 20'. Chlorine yields from irradiated carbon tetrachloride are slightly smaller a t i 0 f 4" than at 20 . The corresponding G-values are 0.58 and 0.65.The addition of hexachloroethane to carbon tetrachloride prior to irradiation causes a nearly linear decrease in G(cin) with per cent. hexachloroethane. The addition of hexachloroethane to chloroform rior to irradiation causes, a t low doses, an increase in G(Hc~) above that in pure chloroform. G(nci, in chloroform-hexachEroethane mixtures decreases with dose and above approximately 1 x 1021 e.v. per gram, becomes less than in pure chloroform. These results are discussed in terms of free radical mechanisms.

How radiolysis impacts astatine speciation?

“…A large number of reports have previously focused on chloroform radiolysis in various contexts and experimental conditions (Abadie, 1982;Bibler and Hyder, 1968;Chen et al, 1960;Johnston et al, 1961;Ottolenghi and Stein, 1961;Schulte et al, 1953;Werner and Firestone, 1965). These authors suggested that hydrogen chloride is the main product of chloroform radiolytic degradation.…”

“…However, all these publications (from the 50's to the 80's) gave equivocal radiolytic yield (G-yield) of generated hydrogen chloride because of differences in the experimental conditions. Either chloroform solutions purity were different which implies discrepancies in G-yield of HCl (Abadie, 1982;Chen et al, 1960;Johnston et al, 1961;Ottolenghi and Stein, 1961) or experimental conditions, for example various temperature, pressure or radiation dose rate (Bibler and Hyder, 1968;Johnston et al, 1961;Schulte et al, 1953;Werner and Firestone, 1965). For these reasons, we planned to revisit the experimental measurements of HCl yield during γ-ray experiments, more easy to be measured and close to the α ones, in specifically well-defined conditions in order to establish the potential quantities of HCl in routine production of astatine-211 solution during radiolabeling and production of [ 211 At]-astatinated radiopharmaceuticals.…”