Probing the Redox Reactivity of Alkyl Bound Astatine: A Study on the Formation and Cleavage of a Stable At–C Bond

The formation of a stable alkyl At-C bond occurs during the shipment of ²¹¹At on a 3-octanone-impregnated column and the reactivity of ²¹¹At stripped from columns has been studied. The ²¹¹At could not be recovered from the 3-octanone organic phase using nitric acid or sodium hydroxide, even up to 10 and 15.7 M, respectively. Several reducing and oxidizing agents, including hydrazine, hydroxylamine, ascorbic acid, ceric ammonium nitrate, potassium permanganate, sodium hypochlorite, and calcium hypochlorite were used to promote the recovery of ²¹¹At. The most effective reducing agent was hydroxylamine, where ∼70% of the ²¹¹At was recovered, while among oxidizing agents ceric ammonium nitrate, potassium permanganate, and sodium hypochlorite all showed near quantitative recovery of ²¹¹At. These results indicate an At-C bond is being formed during the shipment of the column and a redox reaction is required for bond cleavage to occur. DFT calculations have been used to propose several products of an AtO⁺-3-octanone reaction, with 4-astato-5-hydroxy-octa-3-one being the most probable.