Kinetics and mechanisms of the Bamberger rearrangement. Part 3. Rearrangement of phenylhydroxylamines to p-aminophenols in aqueous sulphuric acid solutions

Takaaki Sone, Yuuji Tokuda, Toshimi Sakai, Seiji Shinkai, Osamu Manabe

研究成果: ジャーナルへの寄稿記事

51 引用 (Scopus)

抄録

The rates of Bamberger-type rearrangement of phenylhydroxylamine (1a) and its derivatives (1b-d) to the corresponding p-aminophenols were determined in sulphuric acid solution. Plots of the pseudo-first-order rate constants against pH (or H0) indicate that the active species at [H2SO4] < 1.00N (pH region) is the O-protonated arylhydroxylamine (ArNHO+H2) which exists in equilibrium with the N-protonated species (ArN+H2OH), while the diprotonated species (ArN+H2O+H2) contributes significantly to the observed reaction rate at [H2SO4] > 1.00N (H0 region). The slope of Hammett plots (ρ) which was obtained by plotting kobs at [H2SO4] 1.00N against the Hammett σ values was -3.19. It was also established that the ΔS‡ values for the four substrates are all positive. These results suggest that the Bamberger rearrangement occurs by an SN1 mechanism and that the elimination of water from ArNHO+H2 is rate determining.

元の言語英語
ページ(範囲)298-302
ページ数5
ジャーナルJournal of the Chemical Society, Perkin Transactions 2
発行部数2
出版物ステータス出版済み - 1981
外部発表Yes

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Rate constants
Derivatives
Kinetics
Acids
Water
Substrates
phenylhydroxylamine
4-aminophenol

All Science Journal Classification (ASJC) codes

  • Chemistry(all)

これを引用

Kinetics and mechanisms of the Bamberger rearrangement. Part 3. Rearrangement of phenylhydroxylamines to p-aminophenols in aqueous sulphuric acid solutions. / Sone, Takaaki; Tokuda, Yuuji; Sakai, Toshimi; Shinkai, Seiji; Manabe, Osamu.

:: Journal of the Chemical Society, Perkin Transactions 2, 番号 2, 1981, p. 298-302.

研究成果: ジャーナルへの寄稿記事

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abstract = "The rates of Bamberger-type rearrangement of phenylhydroxylamine (1a) and its derivatives (1b-d) to the corresponding p-aminophenols were determined in sulphuric acid solution. Plots of the pseudo-first-order rate constants against pH (or H0) indicate that the active species at [H2SO4] < 1.00N (pH region) is the O-protonated arylhydroxylamine (ArNHO+H2) which exists in equilibrium with the N-protonated species (ArN+H2OH), while the diprotonated species (ArN+H2O+H2) contributes significantly to the observed reaction rate at [H2SO4] > 1.00N (H0 region). The slope of Hammett plots (ρ) which was obtained by plotting kobs at [H2SO4] 1.00N against the Hammett σ values was -3.19. It was also established that the ΔS‡ values for the four substrates are all positive. These results suggest that the Bamberger rearrangement occurs by an SN1 mechanism and that the elimination of water from ArNHO+H2 is rate determining.",
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AU - Sone, Takaaki

AU - Tokuda, Yuuji

AU - Sakai, Toshimi

AU - Shinkai, Seiji

AU - Manabe, Osamu

PY - 1981

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N2 - The rates of Bamberger-type rearrangement of phenylhydroxylamine (1a) and its derivatives (1b-d) to the corresponding p-aminophenols were determined in sulphuric acid solution. Plots of the pseudo-first-order rate constants against pH (or H0) indicate that the active species at [H2SO4] < 1.00N (pH region) is the O-protonated arylhydroxylamine (ArNHO+H2) which exists in equilibrium with the N-protonated species (ArN+H2OH), while the diprotonated species (ArN+H2O+H2) contributes significantly to the observed reaction rate at [H2SO4] > 1.00N (H0 region). The slope of Hammett plots (ρ) which was obtained by plotting kobs at [H2SO4] 1.00N against the Hammett σ values was -3.19. It was also established that the ΔS‡ values for the four substrates are all positive. These results suggest that the Bamberger rearrangement occurs by an SN1 mechanism and that the elimination of water from ArNHO+H2 is rate determining.

AB - The rates of Bamberger-type rearrangement of phenylhydroxylamine (1a) and its derivatives (1b-d) to the corresponding p-aminophenols were determined in sulphuric acid solution. Plots of the pseudo-first-order rate constants against pH (or H0) indicate that the active species at [H2SO4] < 1.00N (pH region) is the O-protonated arylhydroxylamine (ArNHO+H2) which exists in equilibrium with the N-protonated species (ArN+H2OH), while the diprotonated species (ArN+H2O+H2) contributes significantly to the observed reaction rate at [H2SO4] > 1.00N (H0 region). The slope of Hammett plots (ρ) which was obtained by plotting kobs at [H2SO4] 1.00N against the Hammett σ values was -3.19. It was also established that the ΔS‡ values for the four substrates are all positive. These results suggest that the Bamberger rearrangement occurs by an SN1 mechanism and that the elimination of water from ArNHO+H2 is rate determining.

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