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Phenyl Chloroformate와 置換아닐린의 反應에 대한 置換期 效果 및 메카니즘 硏究

Title 
Phenyl Chloroformate와 置換아닐린의 反應에 대한 置換期 效果 및 메카니즘 硏究
Other Titles 
Study of Mechanism and Substituent Effects of the Reaction of Phenyl Chloroformate with Substituted Anilines
Authors 
沈光澤
Authors 
呂壽東
Issue Date 
1986
Journal 
연구논문집
Vol. 
Vol.11
Issue 
No. 1
Pages 
37-42
Abstract 
Phenyl chloroformate와 치환아닐린과의 反應速度를 電氣傳導度法으로 測定하여 置換基效果 및 反應 메카니즘을 검토하였다. 치환아닐린의 치환기效果를 보면 electron-donating 基는 electron-withdrawing 基보다 더 빠르다. Hammett plot에서 electron-donating 基일 때, log(k_2)=-4.61σ(σ^-)+1.77(γ=0.98) in acetone at 10℃, electron-withdrawing 基일 때, log(k_2)=-0.73σ(σ^-)+1.12(γ=0.98) in acetone at 10℃로서 기울기(ρ 값)가 다른 2개의 直線關係가 成立하여 速度 決定段階가 달랐다. Brφnsted plot 에서도 β값이 다른 2개의 직선관계를 나타내었고 ΔH^≠와 ΔS^≠ 사이에도 전자-주게와 전자-끌게기가 별도의 等速關係를 보였고 entropy값은 添加-除去 메카니즘을 갖는 類似반응의 entropy 값과 잘 일치하였다. 이상의 결과와 置換基效果를 고려할 때 S_AE 메카니즘으로 진행됨을 제의한다.
The second-order rate constants of carbamate formation from phenyl cholroformate and substituted anilines were determined conductometrically in acetone. The effect of substituent of substituted anilines were discussed. The amidation of phenyl chloroformate with several anilines of election-donating groups are faster than that of anilines of electron-withdrawing groups. [For example, k_2 values: 1.91(p-Me, at 0℃), 1.22 × 10 exp (-2) (p-NO_2, at 0℃)]. Hammett-type plots of the rate date with σ(σ^-) gave two straight lines
for anilines with electron donating group: log(k_2)=-4.61σ(σ^-)+1.77(γ=0.98) in acetone at 0℃, for anilines with electron-withdrawing groups: log(k_2)=-0.73σ(σ^-)+1.12(γ=0.98) in acetone at 10℃. Based on the Hammett plots, Brφnsted plats and activation entropy, we assume an addition-elimination mechanism for the amidation of phenyl chloroformate with substituted anilines. In the case of anilines with election-donating substituents, the rate of C-N bond formation increase and also assist the rate of Cl^- elimination. Therefore, the rate-determining step seems to be Cl^- elimination. On the other hand, in the case of anilines with electron-withdrawing groups, they decrease not only the rate of C-N bond formation but the rate of Cl^- elimination. Thus C-N bond formation become rate-determining step.
URI 
http://repository.uc.ac.kr/handle/2014.oak/831
ISSN 
1598-3390
Appears in Collections
19. 환경화학공업과 > 연구논문

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