Takumi Maeda

Potassium-selective PVC membrane electrodes based on bis- and poly(crown ether)s

Abstract Potassium-selective PVC membrane electrodes based on bis- and poly (crown ether)s containing benzo-15-crown-5 moiety as neutral carrier were prepared and selectivity coefficients for various monovalent ions were measured in order to elucidate the effect of complexing property of these crown ether derivatives on the electrode response. In the preference for potassium over sodium of the electrodes, these bis- and poly (crown ether)s were found to exceed the corresponding monocyclic crown ether considerably, which reflects the easy complexation of stable 2:1 complexes of crown ether ring and ion, derived from the cooperative effect of two adjacent crown ether rings.

Extraction of alkali metal picrates with poly- and bis(crown ether)s.

Extraction of alkali metal picrates by new poly- and bis(crown ether)s containing benzo-15-crown-5 and benzo-18-crown-6 moieties was carried out with chloroform as water-immiscible solvent. The poly- and bis(crown ether)s were found to extract the picrates more effectively than the corresponding monocyclic crown ethers. In particular, poly- and bis(benzo-15-crown-5), and bis(benzo-18-crown-6) are remarkably effective extracting reagents for potassium and rubidium, and for caesium, respectively. Extraction equilibrium constants and the complexation constants in the chloroform phase were also evaluated and the contribution of the complexation constants to the extractability is discussed.

Properties of cis- and trans-bis(crown ether)s for complexation and extraction of alkali metal picrates.

The properties of cis- and trans-bis(crown ether)s containing benzo-15-crown-5 or benzo-18-crown-6 units as complexants and extractants for alkali metal picrates have been studied. The optical spectra suggest that the cis-bis(crown ether)s can form intramolecular 2:1 crown ether unit/cation complexes with particular metal cations easily, while the trans-bis(crown ether)s can form only 1:1 crown ether unit/cation complexes because of the unfavourable trans configuration for the formation of the 2:1 complexes. It was found that the cis isomer possesses much higher extractive power than the trans isomer for the metal cations, which also reflects their complexing properties. The extraction equilibrium constants and thermodynamic quantities have been also evaluated, and the effect of the stereochemical structure of the bis(crown ether) on the complexing and extractive properties is discussed.

New Poly - and Bis(crown ether)s as Extracting Reagents

Abstract New poly- and bis(crown ether)s containing benzo-15-crown-5 or benzo-18-crown-6 moieties were synthesized as extracting reagents, and by a preliminary solvent extraction of alkali metal picrates the poly- and bis-(crown ether)s were found to extract the cations capable of forming sandwich-type 2:1 complexes more effectively than their monomeric analogs.

Solvent extraction of silver and thallium picrates with poly- and bis-(crown ether)s

ZusammenfassungDie Extraktion der Pikrate wurde in Wasser/Chloroform mit neuen Poly- und Bis-Kronenethern durchgeführt, die Benzo-15-Krone-5- oder Benzo-18-krone-6-Komponenten enthielten. Die Poly- und Bis-Kronenether wiesen für beide Metalle eine bessere Extrahierbarkeit auf als die entsprechenden monocyclischen Kronenether. Insbesondere Poly- und Bis(benzo-15-krone-5) erwiesen sich als wirkungsvolle Extraktionsmittel für Thallium(I). Die Extraktions-Gleichgewichtskonstanten und die Komplexbildungskonstanten für die Chloroformphase wurden bestimmt.SummarySolvent extraction of silver and thallium picrates by new poly- and bis(crown ether)s, which contain benzo-15-crown-5 or benzo-18-crown-6 moieties, was carried out in water-chloroform system. The poly- and bis(crown ether)s showed higher extractability for both metals than the corresponding monocyclic crown ethers.Especially poly- and bis(benzo-15-crown-5) were found to be quite effective extracting agents for Tl+.The extraction equilibrium constants and the complexation constants for the chloroform phase were also estimated.

Tactic poly(crown ether)s with pendant benzocrown ethers

SummaryTactic and atactic poly(crown ether)s, poly(methacryloyloxymethylbenzo-15-crown-5), were synthesized by polymer reaction of the respective poly(methacrylic acid) with chloromethylbenzo-15-crown-5 and radical polymerization of methacryloyloxymethylbenzo-15-crown-5. By solvent extraction of alkali metal picrates with these poly(crown ether)s, the isotactic poly(crown ether) was found to be a little more selective for K+ and Rb+ than the syndiotactic and atactic ones.

Solvent Extraction of Alkaline Earth Metal Picrates with Poly- and Bis(Crown Ether)s

ZusammenfassungPoly- und Bis-Kronenether mit Benzo-15-krone-5- und Benzo-18-krone-6-Einheiten wurden zur Extraktion von Erdalkalipikraten im Wasser-Chloroform-System verwendet. Die genannten Ether zeigten eine bessere Extraktionsfähigkeit für die Pikrate als die entsprechenden monocyclischen Kronenether. Im Falle von Ba2+ und Sr2+ ergab sich eine besonders gute Extrahierbarkeit und Selektivität mit Poly- und Bis(benzo-15-krone-5)- und Bis(benzo-18-krone-6)-Ethern.SummarySolvent extraction of alkaline earth metal picrates with poly- and bis(crown ether)s containing benzo-15-crown-5- and benzo-18-crown-6 moieties was carried out in a water-chloroform system. The poly- and bis(crown ether)s showed larger extractability for the metal picrates than the corresponding monocyclic crown ethers. Especially, poly- and bis(benzo-15-crown-5), and bis(benzo-18-crown-6) were found to have relatively high extractability and selectivity for Ba2+ and Sr2+, respectively.

Cation-binding properties of poly- and bis(benzo-21-crown-7)derivatives

ZusammenfassungPoly- und Bis-kronenether mit dem relativ großen Kronenetherring Benzo-21-krone-7 wurden dargestellt und ihr Bindungsvermögen für Alkaliionen wurde durch Lösungsextraktion und auch konduktometrisch untersucht. Es ergab sich, daß das Bindungsvermögen in der Reihenfolge Cs+>Rb+>K+>Na+ abnimmt. Diese Substanzen können Alkaliionen wirksamer extrahieren als die entsprechenden Monomeren Analogen. Das Bindungsvermögen für einige organische Kationen, wie z.B. Alkylammonium und Guanidinium, wurde ebenfalls untersucht.SummaryPoly- and bis(crown ether)s which contain the relatively large crown ether ring of benzo-21-crown-7 were synthesized, and their cation-binding properties for alkali metal cations were elucidated by solvent extraction and also conductometrically. The cation-binding ability was found to decrease in the order Cs+>Rb+>K+>Na+. They can extract alkali metal cations more efficiently than the corresponding monomeric analogue. The binding behaviour for some organic cations such as alkyl ammonium and guanidinium is also described.