Elimination reactions of aryl furylacetates promoted by r <inf>2</inf>NH-r<inf>2</inf>NH<inf>2</inf> <sup>+</sup> in 70 mol% MeCN(aq). effects of β-aryl on the ketene-forming transition-state

Sang Yong Pyun, Ju Chang Kim, Bong-Rae Cho

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2 Citations (Scopus)

Abstract

Ketene-forming elimination from 2-X-4-nitrophenyl furylacetates (1a-d) promoted by r<inf>2</inf>NH-r<inf>2</inf>NH<inf>2</inf> <sup>+</sup> in 70 mol % MeCN(aq) has been studied kinetically. When X = Cl and NO<inf>2</inf>, the reactions exhibited second-order kinetics as well as Brönsted β = 0.37-0.54 and |βlg| = 0.31-0.45. The Brönsted β decreased with a poorer leaving group and |βlg| increased with a weaker base. The results are consistent with an E2 mechanism. When the leaving group was changed to a poorer one [X= H (1a) and OCH3 (1b)], the reaction mechanism changed to the competing E2 and E1cb mechanisms. A further change to the E1cb mechanism was realized for the reaction of 1a with i-Pr2NH/i-Pr2NH<inf>2</inf> + in 70 mol % MeCN-30 mol % D<inf>2</inf>O. By comparing the kinetic results in this study with the existing data for ArCH<inf>2</inf>C(O)OC<inf>6</inf>H3-2-X-4-NO <inf>2</inf>, the effect of the β-aryl group on the ketene-forming elimination was assessed.

Original languageEnglish
Pages (from-to)2143-2147
Number of pages5
JournalBulletin of the Korean Chemical Society
Volume35
Issue number7
DOIs
Publication statusPublished - 2014 Jul 20

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Kinetics
ketene
4-nitrophenyl

Keywords

  • E2 and E1cb Mechanism
  • Elimination
  • β-Aryl Group effect

ASJC Scopus subject areas

  • Chemistry(all)

Cite this

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title = "Elimination reactions of aryl furylacetates promoted by r 2NH-r2NH2 + in 70 mol{\%} MeCN(aq). effects of β-aryl on the ketene-forming transition-state",
abstract = "Ketene-forming elimination from 2-X-4-nitrophenyl furylacetates (1a-d) promoted by r2NH-r2NH2 + in 70 mol {\%} MeCN(aq) has been studied kinetically. When X = Cl and NO2, the reactions exhibited second-order kinetics as well as Br{\"o}nsted β = 0.37-0.54 and |βlg| = 0.31-0.45. The Br{\"o}nsted β decreased with a poorer leaving group and |βlg| increased with a weaker base. The results are consistent with an E2 mechanism. When the leaving group was changed to a poorer one [X= H (1a) and OCH3 (1b)], the reaction mechanism changed to the competing E2 and E1cb mechanisms. A further change to the E1cb mechanism was realized for the reaction of 1a with i-Pr2NH/i-Pr2NH2 + in 70 mol {\%} MeCN-30 mol {\%} D2O. By comparing the kinetic results in this study with the existing data for ArCH2C(O)OC6H3-2-X-4-NO 2, the effect of the β-aryl group on the ketene-forming elimination was assessed.",
keywords = "E2 and E1cb Mechanism, Elimination, β-Aryl Group effect",
author = "Pyun, {Sang Yong} and Kim, {Ju Chang} and Bong-Rae Cho",
year = "2014",
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day = "20",
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AU - Pyun, Sang Yong

AU - Kim, Ju Chang

AU - Cho, Bong-Rae

PY - 2014/7/20

Y1 - 2014/7/20

N2 - Ketene-forming elimination from 2-X-4-nitrophenyl furylacetates (1a-d) promoted by r2NH-r2NH2 + in 70 mol % MeCN(aq) has been studied kinetically. When X = Cl and NO2, the reactions exhibited second-order kinetics as well as Brönsted β = 0.37-0.54 and |βlg| = 0.31-0.45. The Brönsted β decreased with a poorer leaving group and |βlg| increased with a weaker base. The results are consistent with an E2 mechanism. When the leaving group was changed to a poorer one [X= H (1a) and OCH3 (1b)], the reaction mechanism changed to the competing E2 and E1cb mechanisms. A further change to the E1cb mechanism was realized for the reaction of 1a with i-Pr2NH/i-Pr2NH2 + in 70 mol % MeCN-30 mol % D2O. By comparing the kinetic results in this study with the existing data for ArCH2C(O)OC6H3-2-X-4-NO 2, the effect of the β-aryl group on the ketene-forming elimination was assessed.

AB - Ketene-forming elimination from 2-X-4-nitrophenyl furylacetates (1a-d) promoted by r2NH-r2NH2 + in 70 mol % MeCN(aq) has been studied kinetically. When X = Cl and NO2, the reactions exhibited second-order kinetics as well as Brönsted β = 0.37-0.54 and |βlg| = 0.31-0.45. The Brönsted β decreased with a poorer leaving group and |βlg| increased with a weaker base. The results are consistent with an E2 mechanism. When the leaving group was changed to a poorer one [X= H (1a) and OCH3 (1b)], the reaction mechanism changed to the competing E2 and E1cb mechanisms. A further change to the E1cb mechanism was realized for the reaction of 1a with i-Pr2NH/i-Pr2NH2 + in 70 mol % MeCN-30 mol % D2O. By comparing the kinetic results in this study with the existing data for ArCH2C(O)OC6H3-2-X-4-NO 2, the effect of the β-aryl group on the ketene-forming elimination was assessed.

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