Lead selective lipophilic acyclic diionizable polyethers.

A structural series of acyclic polyether dicarboxylic acids with n-butyl and n-tetradecyl alkyl side chains at the alpha-position of the carboxylic acid units, as well as varying lengths of the ethylene glycol ether linkage connecting two benzo units were prepared. In terms of stability constants, competitive solvent extraction and cation transport experiment by bulk liquid membrane toward transition metal ions, ligand 3 with a monoethylene glycol unit and n-butyl side chains provide the best selectivity for the lead ion.