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Journal of the Korean Chemical Society (JKCS)

ISSN 1017-2548(Print)
ISSN 2234-8530(Online)
Volume 37, Number 1
JKCSEZ 37(1)
February 20, 1993 

Substituent Effects on the Wallach Rearrangement of 4'-Halogenated Azoxybenzenes in Conc. Sulfuric Acid : Reaction Mechanism and Linear Free Energy Relationship

황산 수용액내에서 4'-Halogenated Azoxybenzenes의 Wallach Rearrangement 반응에 대한 치환체효과 : 반응메카니즘과 Linear Free Energy Relationship
Sam-Rok Keum, Hyo-Il Lee

금삼록, 이효일
진한 황상 용액에서 4'-halogenated azoxybenzene 유도체의 Wallach 자리옮김 반응을 UV-Vis 분광학적 방법으로 재조사하였다. 흥미롭게도 log(rate)와 pi 비편재화 파라미터라 불리우는 치환체 상수, σR+와의 도시에서 아주 좋은 직선관계(logkobs=-0.61 σR+ -3.29, γ = 0.998)를 얻었다. 그 겨로가로 공명효과에 의해 크게 안정화될 수 있는 즉 + 전하를 가진(DC++)중간체를 거치는 B-L 메카니즘이 Wallach 재배열 반응에 더욱 강력히 주장된다.

The Wallach rearrangement of 4'-halogenated azoxybenzenes in strong sulfuric acid was reinvestigated by UV-Vis spectrophotometric method. Interestingly an excellent linearity (logkobs = -0.61 σR+ -3.29, γ = 0.998) was obtained on plotting log (rate) vs. substituent constant, σR+, which is known as the Pi delocalization parameter. Thus B-H mechanism via a charged intermediate (DC++), which can be largely stabilized by resonance, is far more favored for the Wallach rearrangement.

148 - 153
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