Polymer pendant crown thioethers:: synthesis, characterization and Hg2+ extraction studies of polymer-supported thiacrowns ([14]aneS4 and [17]aneS5)

We are interested in designing polymer-bound extractants fur Hg2+ remediation in mixed-waste streams. Towards this goal, we have synthesized novel polymer extractants where 2-aminomethylthiacrowns are immobilized on a polystyrene-divinylbenzene matrix through the pendant arm of the crowns. Reaction of 2,3-dimercapto-1-propanol with either 4,7-dithiadecane-1, 10-di-p-toluenesulfonate or 4,7, 10-trithiatridecane-1,13-di-p-toluenesulfonate generated the 2-hydroxymethylthiacrowns, 3 ([14]aneS(4)-OH) and 4 ([17]aneS(5)-OH). Treatment of the 2-hydroxymethylthiacrowns with thionyl chloride, followed by monomethylamine, produced the N-(methyl)-2-aminomethylthiacrowns, 5 [14]aneS(4)-(NRR2)-R-1) and 6 ([17]aneS(5)-N (RR2)-R-1) (R-1 =Me, R-2 = H). The thiacrown polymers were prepared through the copolymerization of a 4-vinylbenzyl-substituted aminomethylthiacrown, 7 ([14]aneS(4)-N (RR2)-R-1) or 8 ([17]aneS(5)-N (RR2)-R-1) (R-1 = Me, R-2 = 4-vinylbenzyl), with divinylbenzene, Extraction of Hg2+ from aqueous media using the [17]aneS(5) thiacrown polymer 10 with under a variety of conditions ([Hg2+] 4-200 ppm, pH 1.5-6.2) shows that the resin effectively and selectively removes Hg2+ ions from acidic aqueous solutions with extraction efficiency similar to 95%. Mercury recovery and polymer regeneration was also demonstrated using chloroform solutions of diphenylthiocarbazone to strip the bound Hg2+ from the resin. (C) 2000 Elsevier Science B.V. All rights reserved.