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Journal of the Korean Chemical Society (JKCS)

ISSN 1017-2548(Print)
ISSN 2234-8530(Online)
Volume 28, Number 5
JKCSEZ 28(5)
October 20, 1984 

Kinetics and Mechanism of the Hydrolysis of Phenyl N-Benzenesulfonylchloroformimidate Derivatives

Phenyl N-Benzenesulfonylchloroformimidate 유도체의 가수분해 반응메카니즘과 반응속도론적 연구
Nack-Do Sung, Ki-Sung Kwon, Tae-Rin Kim

성낙도, 권기성, 김태린
새로운 4가지의 phenyl N-benzenesulfonylchloroformimidate 유도체를 합성하고 25℃와 1 ; 4 dioxane-물의 이성분 혼합용매중에서 가수분해 반응속도를 자외선 분광 광도법으로 측정하여 넓은 pH범위에 적용되는 가수분해 반응속도식을 유도하였다. 치환기 효과(ρ = -0.45, ρ = 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 SN1, 그리고 pH 10.0이상의 알카리성 용액에서는 SN2반응으로 가수분해가 시작되어 E1CB반응으로 benzensulfonamide를 생성하는 일련의 반응으로 가수분해가 진행됨을 알았다.

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℃. Hammett ρ values measured at pH 5.0 (ρ = -0.45) and pH 10.0 (ρ = 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 SN1 below pH 8.0, however, above pH 10.0, the hydrolysis proceeds through SN2 and in the range of pH 8.0-10.0, these two reactions occur competitively.

328 - 334
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