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Journal of the Korean Chemical Society (JKCS)

ISSN 1017-2548(Print)
ISSN 2234-8530(Online)
Volume 35, Number 3
JKCSEZ 35(3)
June 20, 1991 

Kinetic Studies on the Nucleophilic Addition of Thiourea to β-Nitrostyrene Derivatives

β-Nitrostyrene 유도체에 대한 Thiourea의 친핵성 첨가반응에 관한 반응속도론적 연구
Tae-Rin Kim, Yeun-Soo Chung, Myung-Sook Chung

김태린, 정연수, 정명숙
β-nitrostyrene 유도체(p-H, p-Cl, p-CH3, p-OCH3, p-NO2)에 대한 thiourea의 친핵성 첨가반응속도를 자외선 분광분석법으로 측정하여 pH에 따르는 반응속도 상수의 변화, general base 및 치환기 효과등으로부터 넓은 pH 범위에서 실험치와 잘 일치하는 반응속도식을 구하였고, 실험사실에 잘 맞는 반응 메카니즘을 제안하였다. 즉, pH 9.00 이상에서의 반응속도는 hydroxide ion의 농도에 비례하는 sulfide anion이 첨가되는 전형적인 Michael type의 반응이 일어나며, pH 9.00 ~ 7.00에서는 thiourea의 중성분자와 그의 anion들이 경쟁적으로 첨가되며 pH 7.00 이하에서는 thiourea의 중성분자만이 첨가됨을 알았다.

The rate constants for the nucleophilic addition reactions of thiourea to β-nitrostyrene derivatives(p-H, p-Cl, p-CH3, p-OCH3, p-NO2) were determined by UV spectrophotometer and rate equations which can be applied over a wide pH ranges were obtained. On the basis of substituent effect, general base catalysis and rate equations, a reaction mechanism was proposed and revealed quantitively. Above pH 9.00, sulfide anion adds to the double bond(Michael type addition) and between pH 7.00 and 9.00, the neutral molecules and its anions add to the double bond competitively. Below pH 7.00, the addition reaction to double bond is initiated by the addition of neutral thiourea molecule.

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