CHROMOGENIC AND FLUOROGENIC GROWN ETHER COMPOUNDS FOR THE SELECTIVE EXTRACTION AND DETERMINATION OF HG(II)

Two novel crown ether compounds, ydroxy-5-nitrobenzyl)-4,13-diazadiben zo-18-crown-6 (CCE) and coumarin-8-methylene)-4,13-diazadibenzo-18-cro wn-6 (FCE), have been synthesized as potential reagents for the select ive extraction and determination of heavy metal ions, Characterization s of the acid-base reactivity and the heavy metal ion extraction capab ilities are reported, Both CCE and FCE undergo four-step ionization pr ocesses with associated tautomeric transformations and form stable com plexes with divalent metal cations that can be extracted into 1,2-dich loroethane, Extraction constants for Ba(II), Ca(II), Cd(II), Cu(II), H g(II), Pb(II), and Sr(II) have been determined for both reagents, For CCE, the extraction order is Hg(II) much greater than Pb(II) > Cu(II) > Cd(II) > Ca(II) > Sr(II) > Ba(II), whereas the order for FCE is Hg(I I) much greater than Cu(II) > Pb(II) > Cd(II) > Ca(II) > Sr(II) > Ba(I I), The selectivity of CCE for Hg(II) over the next-best-extracted cat ion, Pb(II), is similar to 2 x 10(7) and that of FCE for Hg(II) over n ext-best-extracted cation, Cu(II), is similar to 5 x 10(6), Potential applications to chemical analysis, based on the unprecedented selectiv ity of both reagents for Hg(II), are briefly examined.