Journal of the Korean Chemical Society (대한화학회지)

Korean Chemical Society (대한화학회)
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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

  • Keum Sam-Rok (Department of Chemistry, College of Science and Technology) ;
  • Lee Hyo-Il (Department of Chemistry, College of Science and Technology)
  • 금삼록 (고려대학교 자연과학대학 화학과) ;
  • 이효일 (고려대학교 자연과학대학 화학과)
  • Published : 1993.01.20
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Abstract

The Wallach rearrangement of 4'-halogenated azoxybenzenes in strong sulfuric acid was reinvestigated by UV-Vis spectrophotometric method. Interestingly an excellent linearity $(logk_{obs}=-0.61\;{\sigma}_R{^+} -3.29,\;{\gamma = 0.998)$ was obtained on plotting log (rate) vs. substituent constant, ${\sigma}_R{^+}$, 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.

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, ${\sigma}_R{^+}$와의 도시에서 아주 좋은 직선관계$(logk_{obs}=-0.61\;{\sigma}_R{^+} -3.29,\;{\gamma = 0.998)$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.

Keywords

References

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