Comparison of column chromatographic and precipitation methods for the purification of a macrocyclic polyether extractant

Column chromatography on aminopropyl-derivatized silica and precipitation o f a complex with perchloric acid have been evaluated as methods for the pur ification of di-tert-butylcyclohexano-18-crown-6 (DtBuCH18C6), a compound f requently employed for the selective extraction of strontium from acidic ni trate media. Both methods are shown to provide a simple and effective means of eliminating inactive sample components (i.e., impurities or stereoisome rs incapable of extracting strontium) from the crown ether and enriching th e material in 4(z),4'(2) cis-syn-cis DtBuCH18C6, a stereoisomer capable of highly efficient strontium extraction.