Liquid/liquid extraction of metal ions with a polythioether derivative in its reduced bis-mercapto form or its oxidized disulphide form

A linear tetrathioether with thiol groups at both ends, 3,6,9,12-tetrathio-12,14-tetradecanedithiol (TTTD), and its oxidized form, HTCH, a cyclic polythioether containing a disulphide group, were synthesized. The extraction of metal ions by HTCH in the presence of picrate ions is similar to that by a typical thiacrown, 1,4,7,10,13,16-hexathiacyclooctadecane, which has the same number of cyclic sulphur atoms, but is different from that with TTTD. Class ab metals and class b metals react with TTTD. However, most reaction products of these metals are not extracted but form precipitates, except for copper (II), which is ? 99% extracted. These results suggest that the selective separation of metals is possible by the combined use of HTCH and TTTD.