Kinetics and mechanisms of the Bamberger rearrangement. Part 4. Rearrangement of sterically hindered phenylhydroxylamines to 4-aminophenols in aqueous sulphuric acid solution

Takaaki Sone, Kazuhiro Hamamoto, Yoshiyuki Seiji, Seiji Shinkai, Osamu Manabe

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Abstract

The rates of the Bamberger rearrangement of sterically hindered phenylhydroxylamines have been determined in aqueous sulphuric acid solution and the substituent effects (in particular, the steric effects) are discussed. The rate constants for phenylhydroxylamines with 2-substituents (Me, Cl, I) satisfied the Taft equation: log krel = ρ*σ* - δEs with ρ* - 1.93 and δ - 1.16. The result shows that steric hindrance of the substituents, in addition to the electron-donating effect, has an accelerating effect on the rates of the Bamberger rearrangement. The rate constants for 3-substituted 2-methylphenylhydroxylamines were generally greater than those for 5-substituted 2-methylphenylhydroxylamines. The difference was attributed to the ' buttressing effect ' of neighbouring 3-substituents. This is the first example of steric acceleration of the Bamberger rearrangement.

Original languageEnglish
Pages (from-to)1596-1598
Number of pages3
JournalJournal of the Chemical Society, Perkin Transactions 2
Issue number12
Publication statusPublished - 1981
Externally publishedYes

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Rate constants
Kinetics
Acids
Electrons
4-aminophenol
phenylhydroxylamine

All Science Journal Classification (ASJC) codes

  • Chemistry(all)

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Kinetics and mechanisms of the Bamberger rearrangement. Part 4. Rearrangement of sterically hindered phenylhydroxylamines to 4-aminophenols in aqueous sulphuric acid solution. / Sone, Takaaki; Hamamoto, Kazuhiro; Seiji, Yoshiyuki; Shinkai, Seiji; Manabe, Osamu.

In: Journal of the Chemical Society, Perkin Transactions 2, No. 12, 1981, p. 1596-1598.

Research output: Contribution to journalArticle

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abstract = "The rates of the Bamberger rearrangement of sterically hindered phenylhydroxylamines have been determined in aqueous sulphuric acid solution and the substituent effects (in particular, the steric effects) are discussed. The rate constants for phenylhydroxylamines with 2-substituents (Me, Cl, I) satisfied the Taft equation: log krel = ρ*σ* - δEs with ρ* - 1.93 and δ - 1.16. The result shows that steric hindrance of the substituents, in addition to the electron-donating effect, has an accelerating effect on the rates of the Bamberger rearrangement. The rate constants for 3-substituted 2-methylphenylhydroxylamines were generally greater than those for 5-substituted 2-methylphenylhydroxylamines. The difference was attributed to the ' buttressing effect ' of neighbouring 3-substituents. This is the first example of steric acceleration of the Bamberger rearrangement.",
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AU - Sone, Takaaki

AU - Hamamoto, Kazuhiro

AU - Seiji, Yoshiyuki

AU - Shinkai, Seiji

AU - Manabe, Osamu

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N2 - The rates of the Bamberger rearrangement of sterically hindered phenylhydroxylamines have been determined in aqueous sulphuric acid solution and the substituent effects (in particular, the steric effects) are discussed. The rate constants for phenylhydroxylamines with 2-substituents (Me, Cl, I) satisfied the Taft equation: log krel = ρ*σ* - δEs with ρ* - 1.93 and δ - 1.16. The result shows that steric hindrance of the substituents, in addition to the electron-donating effect, has an accelerating effect on the rates of the Bamberger rearrangement. The rate constants for 3-substituted 2-methylphenylhydroxylamines were generally greater than those for 5-substituted 2-methylphenylhydroxylamines. The difference was attributed to the ' buttressing effect ' of neighbouring 3-substituents. This is the first example of steric acceleration of the Bamberger rearrangement.

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