Benzocrown Ether Hydrazones as Extractants for Alkali Metal Ions

Abstract

Four types of benzo-15-crown-5 and benzo-18-crown-6 derivatives bearing a substituted hydrazone moiety as a proton-dissociable chromogenic group were synthesized and the solvent extraction behaviors of these compounds for alkali metal ions were evaluated spectrophotometrically. Benzo-15-crown-5 and -18-crown-6 hydrazones with 2,4-dinitro-6-(trifluoromethyl)phenyl or 2,6-dinitro-4-(trifluoromethyl)phenyl groups extracted alkali metal ions predominantly as 2 : 1 and 1 : 1 (crown ether : metal ion) complexes, respectively, from an aqueous alkaline solution into 1,2-dichloroethane and these ligands exhibited high K+-selectivity. The composition of the extracted species and the K+-selectivity depended on the polarity of the extraction solvent used. In particular, 2 : 2 complexes of several alkali metal ions with benzo-15-crown-5 and -18-crown-6 hydrazones bearing a 2,4-dinitro-6-(trifluoromethyl)phenyl group were readily extracted from an aqueous solution into chloroform.

5-Bromo-2-hydroxybenzaldehyde (4-phenyl-1,3-thiazol-2-yl)hydrazone

“…The chemistry of hydrazones has been intensively investigated in recent years, owing to their coordinating capability, pharmacological activity and antibacterial and antifungal properties, and their use in analytical chemistry as highly selective extractants (Domiano et al, 1984;Sakamoto et al, 1993;Li et al, 1988). Many thiazole ring systems are of considerable importance because of their antibacterial and anti-in¯ammatory activity.…”

(Z)-Ethyl 4-chloro-3-oxo-2-(2-o-tolylhydrazono)butanoate

“…3-Phenylhydrazono-2,4-diones and their derivatives are used for the treatment of cancer or AIDS, or of opportunistic infections afflicting patients with cancer or AIDS (Nathan & Silver, 1997). In addition, the chemistry of hydrazones has been intensively investigated in recent years, owing to their coordinating capability, pharmacological activity and antibacterial and antifungal properties, and their use in analytical chemistry as highly selective extractants (Domiano et al, 1984;Li et al, 1988;Sakamoto et al, 1993). As part of our project studying the crystal structures of a series of phenylhydrazones and their stereochemistry, the crystal structure of the title compound, (I), has been determined.…”

(E)-Ethyl 4-chloro-3-[2-(2-fluorophenyl)hydrazono]butanoate

“…The chemistry of hydrazones has been intensively investigated in recent years, owing to their coordination capability, pharmacological activity and antibacterial and antifungal properties, and their use in analytical chemistry as highly selective extractants (Domiano et al, 1984;Sakamoto et al, 1993;Li et al, 1988). As part of our project studying the crystal structures of a series of phenylhydrazones and their stereochemistry, the crystal structure of the title compound, (I), has been determined.…”