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KMID : 1059519840280020079
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Journal of the Korean Chemical Society
1984 Volume.28 No. 2 p.79 ~ p.85
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The Pressure Effect of the Association of 2,4,6,N-Tetramethyl Pyridinium Iodide in Ethanol-Water Mixture
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Hwang Jung-Ui
Jee Jong-Gi
Lee Young-Hwa
Woo Uei-Ha
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Abstract
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The ionic association constants(K) of 2,4,6,N-tetramethyl pyridinium iodide (TeMPI) in 95 volume percentage ethanol-water mixture were determined by a modified UV and conductance method at 25℃ to 50℃ under 1 to 2,000 bars. The K values increase with increasing pressure and have maximum value at 40℃. The partial molar volume change(ΔV) has relatively small negative value and the absolute values of Δ are minimum at 40℃. The ion size parameter(a) of TeMPI have maximum value at 40℃. ΔH° values are zero, positive and negative at 40℃, 25℃ and 50℃ repectively. Other thermodynamic parameters such as the changes of standard entropy(ΔS°) and free energy(ΔG°) were evaluated. From these experimental results, we came to conclusion that TeMPI is stabilized by the elevation of pressure and that of temperature below 40℃ but weakly dimerized at 40℃ because of the intermolecular hydrophobic interaction of eight methyl groups of two molecules. And it thermally decomposed above 50℃.
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