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Journal of the Korean Chemical Society (JKCS)

ISSN 1017-2548(Print)
ISSN 2234-8530(Online)
Volume 33, Number 1
JKCSEZ 33(1)
February 20, 1989 

Kinetic Studies on the Nucleophilic Addition of 3-Mercaptopropionic Acid to β,β-Diethoxycarbonylstyrene Derivatives

β,β-Diethoxycarbonylstyrene 유도체에 대한 3-Mercaptopropionic Acid의 친핵성첨가반응에 관한 반응속도론적 연구
Tae-Rin Kim, Yun-Chung Choi, Myung-Sook Chung

김태린, 최윤정, 정명숙
β,β-diethoxycarbonylstryene 유도체(H, p-OCH3, 3,4,5-methylenedioxy)에 대한 3-mercaptopropionic acid의 친핵성 첨가반응 속도상수를 자외선 분광법으로 측정하여 넓은 pH 범위에서 적용될수 있는 속도식을 구하였다. pH에 따르는 속도상수의 변화, 일반염기촉매작용등을 바탕으로 이 첨가반응 메카니즘을 제안하였다. 즉 pH 6.0 이하에서는 중성인 3-mercaptopropionic acid 분자의 첨가로 이 반응이 시작되며 pH 6.0∼8.0영역에서는 이 중성분자와 황화음이온의 첨가가 경쟁적으로 일어나며, pH 8.0이상에서는 황화음이온에 의해서만 첨가반응이 진행된다.

The rate constants of the nucleophilic addition reaction of 3-mercaptopropionic acid to the β,β-diethoxycarbonylstryene derivatives (H, p-OCH3, 3,4,5-(OCH3)3, 3,4-methylenedioxy) were determined by ultraviolet spectrophotometry, and rate equation which could be applied over a wide pH range was obtained. On the basis of pH-rate profile and the presence of general base catalysis, a plausible mechanism of this addition reaction was propound:Below pH 6.0 the reaction was initiated by the addition of neutral 3-mercaptopropionic acid molecule, and in the range of pH 6.0∼8.0, a neutral 3-mercaptopropionic acid molecule and a sulfide anion competitively attacked to the double bond. Above pH 8.0, the reaction proceeded through the addition of a sulfide anion.

127 - 134
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