Thermodynamic study of solvent extraction of monovalent metal picrates with benzo-18-crown-6 into chloroform |
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Authors: | Yasuyuki Takeda Takehiro Iwasaki Yoshihiro Kudo Hiroaki Matsuda |
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Institution: | (1) Department of Chemistry, Faculty of Science, Chiba University, Yayoi-cho, 263 Inage-ku, Chiba, Japan |
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Abstract: | Thermodynamic parameters ( H
ex
0
and S
ex
0
) for the overall extractions of monovalent metal (Na, K, Rb, and Tl) picrates with benzo-18-crown-6 (B18C6), and those ( H
D,L
0
and S
D,L
0
) for the distribution of B18C6 were determined between chloroform and water. All the extracted B18C6 complexes were l:1:1 complexes (B18C6:metal ion: picrate anion). The H
ex
0
and S
ex
0
values for all the metals are negative. Every extraction of the metal picrate with B18C6 is completely enthalpy driven. The H
D,L
0
and S
D,L
0
values of B18C6 are both positive, and the partition of B18C6 is entirely entropy driven. Enthalpy ( H
ex,ip
0
) and entropy changes ( S
ex,ip
0
) for ion-pair extractions of B18C6-metal ion complexes with picrate anions were calculated. All the H
ex,ip
0
and S
ex,ip
0
values are negative, and the ion-pair extractions are completely enthalpy driven. |
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Keywords: | Solvent extraction thermodynamics benzo-18-crown-6 monovalent metal picrates chloroform |
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