Gypzy C. Lindh

Proton-ionizable crown compounds : 5. Macrocycle-mediated proton-coupled transport of alkali metal cations in H2OCH2Cl2H2O liquid membrane systems

Abstract Alkali cation transport is studied using proton-ionizable macrocycle carriers of the 4-hydroxypyridine and pyridone types in a bulk H 2 OCH 2 Cl 2 H 2 O liquid membrane system as a function of source and receiving phase pH. A pyridone crown-6 type macrocycle containing an octyl substituent (3) transports Li + , Na + , K + , Rb + and Cs + from MOH solutions by a proton-coupled mechanism in which no co-anion is transported. In these cases, alkali cation transport increases exponentially with increasing source phase pH above pH 12. Generally, alkali cation transport at source phase pH 14 is higher when nitric acid is present (receiving pH = 1.5) than when it is absent. In competitive transport experiments with macrocycle 3 involving K + ) and one other alkali cation M + , K + is transported selectively over M + by 4.6 (Na + ), 2.7 (Rb + ) and 6.3 (Cs + ) fold when the source and receiving phase pH values are 14 and 7, respectively.

Synthesis of macrocyclic acetals containing lipophilic substituents

Abstract A series of new macrocyclic acetals all containing lipophilic substituents were prepared by reacting the appropriate diols and lipophilic acetal-containing dichlorides or ditosylates. The reactions using the ditosylates gave the best yields. Several of the macrocycles contained pyridine subcyclic units. The lipophilic acetals were obtained by reacting a long-chain aldehyde with 2-hydroxyethyl chloride or tosylate and 3-hydroxypropyl chloride or tosylate. At least two of the new pyridino ligands complexed with metal ions as shown by the use of these materials as carriers for silver nitrate through a water-methylene chloride-water bulk liquid membrane system.

Proton ionizable crown compounds. 18. Comparison of alkali metal transport in a H2O-CH2Cl2-H2O liquid membrane system by four proton-ionizable macrocycles containing the dialkylhydrogenphosphate moiety

The macrocycle-mediated fluxes of alkali, alkaline earth, and several transition metal cations have been determined and compared in a H2O-CH2Cl2-H2O liquid membrane system using four water-insoluble macrocycles containing a dialkylhydrogenphosphate moiety. Transport of alkali metal cations by these ligands was greatest from a source phase pH = 12 or above into an acid receiving phase (pH = 1.5). Very low fluxes were observed for the transport of the alkaline earth cations and all transition metal ions studied except Ag+ and Pb2+ which were transported reasonably well by these new macrocycles.

Proton-ionizable crown compounds. 17. Transport studies of alkali metal ions in a H2O-CH2Cl2-H2O liquid membrane system by macrocycles containing two sulfonamide groups derived fromo- andm-phenylene diamine

The transport of alkali metal cations by several macrocycles possessing two sulfonamide groups as a part of an 18-, 20-, or 21-membered macroring has been studied. Some of these compounds were found to be more effective transport agents than the proton-ionizable pyridone- and triazole-containing crown ethers reported previously. The factors affecting transport, such as ring size, source and receiving phase pH, and the nature of the groups attached to the sulfonamide nitrogen atoms were examined. Also, extraction experiments by some of the ligands were performed. The behavior of sulfonamide type crowns in single and competitive transport of the alkali metal cations is explained. The mechanism of transport appears to be complex. Transport of one or two cations per molecule of the disulfonamide carriers occurs. Complexation of these cations appears to occur both within and outside the macrocycle cavity. Our results also suggest that kinetic factors may play a significant role in transport rates and selectivities.

Proton-ionizable crown compounds. 12. Proton-Coupled selective membrane transport of Li+ using a proton-ionizable pyridono macrocycle

The macrocycle-mediated fluxes of several alkali metal cations have been determined in a H2O-CH2Cl2-H2O liquid membrane system. Water-insoluble proton-ionizable macrocycles of the pyridono 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. The desired separation of a particular metal ion involves its selective complexation with the macrocycle, subsequent extraction from the aqueous phase to the organic phase, and exchange for H+ at the organic phase-receiving phase interface. Factors affecting transport which were studied include ring size, source phase pH, and receiving phase pH. Lithium was transported at a rate higher than that of the other alkali metals in both single and competitive systems using a 15-crown-5 pyridono carrier.

Proton-ionizable crown compounds. 11. Synthesis of macrocyclic ligands containing two sulfonamide groups and chloro substituents or pyridine subcyclic units and a preliminary study of cation transport by three of these ligands

Five new macrocyclic ligands each containing two sulfonamide groups have been prepared. Three of these compounds contain one or two chloro substituents and the other two have one or two pyridine subcyclic units. A seventeen-membered ring ligand (4) was found to be an excellent transport agent for all alkali metal cations in a water-methylene chloride-water bulk liquid membrane system when the pH of the source phase was 13 or higher. The chlorine-substituted analog (5) was a poor transport agent for the alkali metal cations possibly because the chlorine atom blocked entry to the macrocycle cavity. An open-chain analog containing two sulfonamide groups was particularly effective in transporting cesium ions.

Alkali cation transport by proton-ionizable macrocycles in a H2O–CH2Cl2–H2O bulk liquid membrane system

Coupled H+–M+(M = Na, K, Rb, or Cs) transport of individual M+ and binary M+ mixtures in which K+ is transported selectively in a 1 M MOH–CH2Cl2–HNO3/H2O (pH 1.5 and ∼6) bulk liquid membrane system has been accomplished using a proton-ionizable 4-pyridone-fused-18-crown-6 macrocycle with an attached C8H17 chain (2).

Proton-Ionizable Crown Compounds: Transport of Alkali and Alkaline Earth Cations Using Proton-Ionizable Triazolo Macrocycles

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.

Synthesis of two new crown ethers containing selenium and the complexation of one of them with silver and lead

Two new macrocyclic crown ethers containing one or two selenium donor atoms have been prepared. Diselena-18-crown-6 (2) was found to transport silver ions through a methylene chloride bulk membrane at about the same rate as the analogous dithia- (3) and diaza-18-crown-6 (4) compounds and transported lead ions about the same as dithia-18-crown-6 but better than diaza-18-crown-6.