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8149978 
Journal Article 
Extraction of sodium and potassium perchlorates with dibenzo-18-crown-6 into various organic solvents. Quantitative elucidation of anion effects on the extraction-ability and -selectivity 
Takeda, Y; Yasui, A; Katsuta, S 
2004 
Yes 
Journal of Inclusion Phenomena and Molecular Recognition in Chemistry
ISSN: 0923-0750 
50 
3-4 
157-164 
English 
WOS:000226207500003 
The constants for overall extraction into various diluents of low dielectric constants (Kex) and aqueous ion-pair formation (K MLA) of dibenzo-18-crown-6 (DB18C6)-sodium and potassium perchlorate 1:1:1 complexes (MLA) were determined at 25°C. The Kex value was analyzed by the four underlying equilibrium constants. The KMLA values were determined by applying our established method to this DB18C6/alkali metal perchlorate extraction system. The KM(DB16C6)A value of the perchlorate is much greater for K+ than for Na+, and is much smaller than that of the picrate. The KMLA value makes a negative contribution to the extractability of DB18C6 for MClO4, whereas the value of the MLA distribution-constant does a major one. The partition behavior of M(DB18C6)ClO4 obeys the regular solution theory. However, the M(DB18C6)ClO4 complexes in the diluent of high dipole moment somewhat undergo the dipole-dipole interaction. DB18C6 always shows high extraction selectivity for KClO4 over NaClO4, which is governed largely by the much greater KMLA value for K + than for Na+. The K+ extraction-selectivity of DB18C6 over Na+ for perchlorate ions is comparable to that for picrate ions. By comparing this perchlorate system with the picrate one, the anion effects on the extraction-efficiency and -selectivity of DB18C6 for Na+ and K+ was discussed in terms of the fundamental equilibrium constants. 
Alkali metal perchlorates; Anion effect; Complexes; Dibenzo-18-crown-6; Dipole moment; Distribution behavior; Extractability; Fundamental equilibria; Ion-pair formation constants in water; Molar volumes; Regular solution theory; Selectivity