Journal of the Korean Chemical Society (대한화학회지)

Korean Chemical Society (대한화학회)
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Kinetics and Mechanism of the Hydrolysis of Phenyl N-Benzenesulfonylchloroformimidate Derivatives

Phenyl N-Benzenesulfonylchloroformimidate 誘導體의 加水分解 反應메카니즘과 反應速度論的 硏究

  • Nack-Do Sung (Department of Agricultural Chemistry, Chungnam National University) ;
  • Ki-Sung Kwon (Department of Chemistry, Chungnam National University) ;
  • Tae-Rin Kim (Department of Chemistry, Korea University)
  • 성낙도 (충남대학교 농과대학 농화학과) ;
  • 권기성 (충남대학교 이과대학 화학과) ;
  • 김태린 (고려대학교 이과대학 화학과)
  • Published : 1984.10.20
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Abstract

A series of phenyl N-benzenesulfonylchloroformimidate derivatives (p-H, p-Cl, p-CH3 & p-OCH3) were prepared and the hydrolysis of these compounds were studied kinetically at various pH by UV spectrophotometry in 1 ; 4 dioxane-water at $25^{\circ}C$. Hammett ${\rho}$ values measured at pH 5.0 (${\rho}$ = -0.45) and pH 10.0 (${\rho}$ = 0.40) indicate that the reaction proceeds via an azocarbonium ion intermediate in the acidic medium, whereas, it involves direct attack by hydroxide ion on the azomethine carbon atom occurs under the basic medium. The formation of stabilized azocarbonium ion species at pH 5.0 is also consistent with the large solvent effect(m = 1.3-1.5 & n = 5.0-5.5). On the basis of these findings, we may concluded that the hydrolysis of phenyl N-benzenesulfonylchloroformimidate derivatives proceeds by $SN_1$ below pH 8.0, however, above pH 10.0, the hydrolysis proceeds through $SN_2$ and in the range of pH 8.0-10.0, these two reactions occur competitively.

새로운 4가지의 phenyl N-benzenesulfonylchloroformimidate 유도체를 합성하고 $25^{\circ}C$와 1 ; 4 dioxane-물의 이성분 혼합용매중에서 가수분해 반응속도를 자외선 분광 광도법으로 측정하여 넓은 pH범위에 적용되는 가수분해 반응속도식을 유도하였다. 치환기 효과(${\rho}$ = -0.45, ${\rho}$ = 0.40), 용매효과 (m = 1.3-1.5, n = 5.0-5.5), 반응속도식 및 생성물 분석 등의 결과로부터 가수분해 반응 메카니즘을 제안하였다. 즉, pH 0.0-8.0의 산성과 중성용액에서는 $SN_1$, 그리고 pH 10.0이상의 알카리성 용액에서는 $SN_2$반응으로 가수분해가 시작되어 $E_1CB$반응으로 benzensulfonamide를 생성하는 일련의 반응으로 가수분해가 진행됨을 알았다.

Keywords

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