Highly Efficient Solvent Extraction of Water-Soluble Macrocyclic Metal Ligands, Hydroxycalix [n] arene-p-sulfonates (n = 4, 6, 8) with Trioctylmethylammonium Chloride

摘要

Water-soluble hydroxycalix [n] arene-p-sulfonates, 1_n~(n-) (n = 4, 6, and 8), were quantitatively extracted from an aqueous solution into chloroform with trioctylmethylammonium ion (TMA~+) over a wide pH range. The extraction reaction of 1_n~(n-) with TMA~+Cl~- and the extraction constants were determined from slope analyses of linearized extraction data and by the mole-ratio method. It was demonstrated that 1_n~(n-), having n moles of sulfonato groups in a aqueous solution, could be extracted as 1_n (TMA~+)_n by associating with n moles of TMA~+ at a pH lower than that at which protonic dissociation of hydroxyl groups takes place, and that 1_n (TMA~+)_((n + j)) was extracted at pH higher than that for j moles of hydroxyl groups dissociate to form 1_n~((n + j)-). The extractability of 1_n~(n-) increased in the order of n (4 < 6 < 8); also, the pH range where complete extraction took place became wider in the same order. As a possible application of the present extraction system, metal extraction with 1_4~(4-) was also shown for the purpose of selective separation of some metal ions.