A Study on the Kinetics and Mechanism of the Hydrolysis of Dihydro-1,4-oxathiin Derivatives

Dihydro-1,4-oxathiin 유도체의 가수분해 Mechanism과 반응속도론적 연구

  • 이광일 (경기대학교 이과대학 화학과) ;
  • 곽천근 (경기대학교 이과대학 화학과) ;
  • 장병만 (경기대학교 이과대학 화학과) ;
  • 김영주 (경기대학교 이과대학 화학과) ;
  • 한호규 (한국과학기술연구원 응용과학연구부) ;
  • 남기달 (한국과학기술연구원 응용과학연구부) ;
  • 이기창 (명지대학교 공과대학 화학공학과)
  • Published : 19960200

Abstract

The kinetics of the hydrolysis of dihydro-1, 4-oxathiin derivatives were investigated by ultraviolet spectrophotometry in H2O at $25^{\circ}C.$ A rate equation which can be applied over a wide pH range was obtained. The substituent effects on the hydrolysis of dihydro-1, 4-oxathiin derivatives were studied and the rate of hydrolysis was shown to be accelerated by electron accepting groups. Final product of the hydrolysis was 2-(2-hydroxyethylthio)acetoacet-anilide enol form. On the basis of rate equations derived and judging from hydrolysis products obtained and from general base effect and substituent effects, plausible mechanism of the hydrolysis in various pH range have been proposed. Below pH 3.5, the hydrolysis was initiated by the protonation and followed by the addition of water to 2-carbon. Above pH 10.0, the hydrolysis was proceeded by the addition of hydroxide to 2-carbon. In the range of pH 4.0∼10.0, the addition of water to dihydro-1,4-oxathiin is rate controlling step.

Keywords

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