Isotopieeffekte bei der Bildung von Natriumkryptaten

The distribution of activity of²²Na⁺ and²⁴Na⁺ in the heterogeneous equilibrium of a cationic exchange resin and the aqueous or methanolic solution was measured in order to evaluate an isotope effect. Using Li⁺-charged ion exchanger in methanol, an enrichment of²⁴Na was observed. If bicyclic aminopolyethers (221, 222) are present in the solution, this effect is not seen. This means that the complexing agents above carry out an enrichment themselves, as could be shown by calculating the corresponding elementary separation factor. The enrichment of²⁴Na on the ion exchanger was measured directly by using Cs⁺-charged exchangers. The analytical method applied is described, and the limits of error are discussed.