The Pressure Effect of the Association of 2,4,6,N-Tetramethyl Pyridinium Iodide in Ethanol-Water Mixture

에탄올-물 혼합용매내에서 2,4,6,N-Tetramethyl Pyridinium Iodide의 회합에 대한 압력효과

  • Jung-Ui Hwang (Department of Chemistry, College of Natural Science, Kyungpook National University) ;
  • Jong-Gi Jee (Department of Chemistry, Teacher's College, Kyungpook National Univeristy) ;
  • Young-Hwa Lee (Department of Chemistry, Teacher's College, Kyungpook National Univeristy) ;
  • Uei-Ha Woo (Department of Chemistry, Teacher's College, Kyungpook National Univeristy)
  • 황정의 (慶北大學校 自然科學大學 化學科) ;
  • 지종기 (慶北大學校 師範大學 化學科) ;
  • 이영화 (慶北大學校 師範大學 化學科) ;
  • 우의하 (慶北大學校 師範大學 化學科)
  • Published : 1984.04.20

Abstract

The ionic association constant(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 $25^{\circ}C$ to $50^{\circ}C$ under 1 to 2,000 bars. The K values increase with increasing pressure and have maximum value at $40^{\circ}C$. The partial molar volume hange (${\Delta}V$) has relatively small negative value and the absolute values of ${\Delta}$ are minimum at $40^{\circ}C$. The ion size parameter(a) of TeMPI have maximum value at $40^{\circ}C$. {\Delta}H^{\circ}$ values are zero, positive and negative at 40^{\circ}C$, $25^{\circ}C$ and $50^{\circ}C$ respectively. Other thermodynamic parameters such as the changes of standard entropy ({\Delta}S^{\circ}$) and free energy {\Delta}G^{\circ}$ were evaluated. From these experimental results, we came to conclusion that TeMPI is stabilized by the elevation of pressure and that of temperature below $40^{\circ}C$ but weakly dimerized at $40^{\circ}C$ because of the intermolecular hydrophobic interaction of eight methyl groups of two molecules. And it thermally decomposed above $50^{\circ}C$.

Keywords

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