Structure-cation complexation relationships for ortho-, meta-, and para-substituted bis(oxymethylcrown)benzenes and α,α'-xylenes

Abstract

New bis(crown ether) compounds are synthesized by attaching two (hydroxymethyl)crown ether units to a benzene or α,α'-xylene framework. Bis(15-crown-5) polyether substitution patterns are varied from ortho to meta to para. ortho-Bis (18-crown-6) polyethers are prepared together with mono(crown ether) analogs, as well as ortho-bis(12-crown-4) polyethers. Complexation abilities of these compounds for alkali metal cations are evaluated by picrate extraction allowing the influence of structural modifications in the ligands on extraction constants (K ex ) and association constants (K a ) for alkali metal cations to be assessed.