Synthesis and study of the extraction properties ofnew phosphorus-containing extractants of heavy metals

Abstract: The metallurgical industry is one of the cornerstones of contemporary chemical science and industry and it is developing rapidly in many countries. The widespread introduction of metal extraction, concentration and separation as the most productive methods entails the need to search for and create new effective metal extractants. Among the compounds, suitable for use as extractants, the most widespread are organic phosphites and phosphates, which allow performing extraction processes with good selectivity and efficiency. The purposes of this article include finalizing the optimal synthesis conditions and developing larger batches of 4,5-dimethyl-2-(2,2,2-trifluoroethoxy)-1,3,2-dioxaphospholane and 5,5-dimethyl-2-(2,2,3,3,4,4,5,5- octafluoropentoxy)-1,3,2-dioxaphosphorinane, and study of the extraction properties of the obtained phosphorus- containing heterocyclic compounds in the separation of uranium from the commercial desorbate. The synthesis of new representatives of the indicated polyfluoroalkylated five- and six-membered heterocyclic phosphorus compounds was conducted using the interaction of 2-chloro-1,3,2-dioxaphospholane with trifluoroethanol and the substitution–cyclization reaction of polyfluoroalkylated dichlorophosphite with 2,2-dimethyl- 1,3-propanediol. Reactions easily proceed in triethylamine–hexane or pyridine–diethyl ether systems at temperatures ranging between minus ten to room temperature, with the output of target heterocycles of 53–57%. The studies of extraction properties of synthesized poly-fluorinealkylated dioxaphospholane and dioxaphosphorinane show that the use of these phosphorus-containing heterocyclic compounds as extractants allows extracting a technically valuable metal up to 12.4 and 15.2%, respectively. Nitric and sulfuric acid solutions of commercial desorbate of hydrometallurgical production in Kazakhstan were used as feedstock in the extraction process.