A thermodynamic study of the association of alkali metal cations with dicyclohexano-18-crown-6 |
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Authors: | Khalid M Tawarah Shehadeh A Mizyed |
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Institution: | (1) Department of Chemistry, Yarmouk University, Irbid, Jordan |
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Abstract: | A thermodynamic study of the association of Na+, K+, Rb+, and Cs+ with dicyclohexano-18-crown-6 in acetonitrile has been carried out at 308, 303, 298, 293, and 288 K using a conductometric technique. The observed molar conductivities, A, were found to decrease significantly for mole ratios less than unity. A model involving 1 1 stoichiometry has been used to analyze the conductivity data. The stability constant,K, and the limiting molar conductivity, A
c
, for each 1 1 complex were determined from the conductivity data by using a nonlinear least squares curve fitting procedure. The binding sequence, based on the value of logK at 298 K, as derived from this study is K+>Na+>Rb+>Cs+. Values of H
o and S
o are reported and their significance is discussed. |
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Keywords: | Dicyclohexano-18-crown-6 alkali cations thermodynamic study crown ethers |
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