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Journal of the Korean Chemical Society (JKCS)

ISSN 1017-2548(Print)
ISSN 2234-8530(Online)
Volume 40, Number 10
JKCSEZ 40(10)
August 20, 1996 

Kinetic Studies on the Nucleophilic Addition of Thioglycolic Acid to S-Phenyl-S-vinyl-N-p-tosylsulfilimine Derivatives

S-Phenyl-S-vinyl-N-p-tosylsulfilimine 유도체에 대한 Thioglycolic Acid의 친핵성 첨가반응에 관한 반응속도론적 연구
Tae Rin Kim, Man So Han, Sang Yong Pyun

Vinylsulfilimine(VSI) 유도체(p-OCH3, H, p-Cl 및 p-Br)에 대한 thioglycolic acid의 친핵성 첨가반응속도를 자외선 분광법으로 측정하여 넓은 pH 범위에서 적용될 수 있는 속도식을 구하였다. pH에 따른 속도상수의 변화, general base 및 치환기 효과 등을 바탕으로 반응 메카니즘을 제안하였다. 즉 pH 3.0 이하에서는 sulfilimine의 질소에 양성자가 먼저 첨가된 다음 중성 thioglycolic acid 분자가 탄소 이중결합에 첨가되고, pH 3.0∼9.0 영역에서는 thioglycolic acid의 중성분자와 음이온의 첨가가 경쟁적으로 일어나며, pH 9.0 이상에서는 황화 음이온이 첨가되는 전형적인 Michael type의 반응이 진행됨을 알았다.

The rate constants for the nucleophilic addition reactions of thioglycolic acid to vinylsulfilimine(VSI) derivatives(p-OCH3, H, p-Cl and p-Br) were determined by an ultraviolet spectrophotometric method, and rate equations which can be applied over a wide pH range were obtained. On the basis of rate equation, general base catalysis and substituent effect, a plausible addition reaction mechanism was proposed: Below pH 3.0, the reaction was proceeded via the addition of neutral molecule to carbon-carbon double bond after protonation at the nitrogen atom of the sulfilimine, and in the pH range of 3.0 to 9.0, the neutral molecule and its anion attacked to carbon-carbon double bond competitively. Above pH 9.0, sulfide anion added to the double bond (Michael type addition).

663 - 669
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