Proton-Ionizable Crown Compounds: Transport of Alkali and Alkaline Earth Cations Using Proton-Ionizable Triazolo Macrocycles
- 1 October 1988
- journal article
- Published by Taylor & Francis in Separation Science and Technology
- Vol. 23 (12) , 1813-1823
- https://doi.org/10.1080/01496398808075665
Abstract
The macrocycle-mediated flaxes of the alkali and alkaline earth metal cations have been determined in a H2O-CH2Cl2-H2O bulk liquid membrane system. Water-insoluble proton-ionizable macrocycles of the triazolo type were used. The proton-ionizable feature allows the coupling of cation transport to reverse H+ transport. This feature offers promise for the effective separation and/or concentration of alkali metal ions with the metal transport being driven by a pH gradient. A counter anion in the source phase is not co-transported. Transport of the alkali cations only occurred when the source phase pH was greater than the aqueous pKa value for the carriers. Transport increased regularly with increasing source phase pH. Transport of alkaline earth cations from neutral pH source phases was minimal. The alkali cation selectivity order was K+ > Rb+ > Cs+ > Na+ > Li+ for the l8-crown-6 sized macrocycles, while little selectivity was observed with the 15-crown-5 sized macro-cycle.Keywords
This publication has 14 references indexed in Scilit:
- Proton‐ionizable crown compounds. 13. Synthesis and structural studies of crown compounds containing the triazole subcyclic unit and lipophilic substituentsJournal of Heterocyclic Chemistry, 1987
- Extraction and transport of alkali metal salts by crown ethers and cryptands: estimation of extraction constants and their relationship to transport fluxCanadian Journal of Chemistry, 1987
- Proton-ionizable crown compoundsJournal of Membrane Science, 1987
- Effect of Macrocycle Type on Pb2+ Transport through an Emulsion Liquid MembraneSeparation Science and Technology, 1987
- The influence of halocarbon solvent on macrocycle-mediated cation transport through liquid membranesJournal of Membrane Science, 1986
- On the rate-limiting steps in the membrane transport of cations across liquid membranes by dibenzo-18-crown-6 and lipophilic crown ether carboxylic acidsJournal of Membrane Science, 1985
- Thermodynamic and kinetic data for cation-macrocycle interactionChemical Reviews, 1985
- Carrier-mediated transport through bulk liquid membranes: dependence of transport rates and selectivity on carrier properties in a diffusion-limited processJournal of the American Chemical Society, 1985
- The influence of macrocyclic ligand structure on carrier-facilitated cation transport rates and selectivities through liquid membranesJournal of Membrane Science, 1981
- The relationship between complex stability constants and rates of cation transport through liquid membranes by macrocyclic carriersJournal of the American Chemical Society, 1980