Journal of the Korean Chemical Society (대한화학회지)

Korean Chemical Society (대한화학회)
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Kinetic Studies on the Mechanism of Hydrolysis of 2-Phenyl-4H,5H-3-methyl-3-thiazolinium Perchlorate Derivatives

2-Phenyl-4H,5H-3-methyl-3-thiazolinium Perchlorate 유도체의 가수분해 반응 메카니즘에 관한 반응속도론적 연구

  • Kim, Tae-Rin (Department of Chemistry, Korea University) ;
  • Lee, So-Young (Department of Chemistry, Korea University) ;
  • Han, Man-So (Department of Chemistry, Daejin University) ;
  • Pyun, Sang-Yong (Department of Chemistry, Pukyong National University) ;
  • Lee, Seok-Hee (Department of Chemical Engineering, Pukyong National University)
  • Published : 2000.04.20
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Abstract

The rate constants for the hydrolysis of 2-phenyl-4H,5H-3-methyl-3-thiazolinium perchlorate(PTP) derivatives were detemined by the use of ultraviolet visible spectrophotometer in water. The rate equations which could be applied over a wide pH ranges were obtained. On the basis of rate equation, hydrolysis product analysis, general base catalysis, and substituent effect, a plausible mechanism of the hydrolysis is proposed: Below pH 4.0, the reaction is initiated by addition of water, while above pH 9.0, Michael type nucleophilic addition takes place. In the pH range of $4.5{\sim}8.0$, these two reactions appear to occur competitively.

2-PhenyI-4H,5H-3-methyl-3-thiazolinium perchlorate(PTP)유도체들의 가수분해속도상수를 수용액에서 자외선 분광법으로 측정하여 넓은 pH 범위에서 적용될 수 있는 속도식을 구하였다. pH에 따른 속도상수의 변화, 가수분해 생성물의 확인, 일반염기 및 치환기 효과 등을 바탕으로 반응 메카니즘을 제안하였다. 즉 pH 4.0 이하에서는 물분자의 첨가가 일어나 가수분해가 진행되며, pH 9.0 이상에서는 전형적인 Michael type의 반응이 일어나며, pH $4.5{\sim}8.0$ 사이에서는 이들 두 반응이 경쟁적으로 일어남을 알았다.

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