Eliminations from (E)-O-arylbenzaldoximes promoted by tertiary amines in acetonitrile. Effects of aryl substituents, base strength, and leaving group upon the nitrile-forming transition state

Bong-Rae Cho, Kee Dong Kim, Jong Chan Lee, Nam Soon Cho

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Abstract

Elimination reactions of (E)-O-(2,4-dinitrophenyl)benzaldoximes (1) and (E)-O-picrylbenzaldoximes (2) with R3N in MeCN have been investigated. The reactions are quantitative, producing only benzonitriles and aryloxides. The observation of second-order kinetics, β = 0.43-0.81, and |β1g| = 0.39-0.73 is consistent with an E2 mechanism. For reactions of 1 with R3N in MeCN, the β and ρ values increased significantly with electron-withdrawing aryl substitutents and stronger bases respectively. The corresponding changes in the β and ρ values for 2 were in the same direction but much less. When the leaving group was changed from 2,4-dinitrophenoxide to picrate, however, β increased and ρ decreased. Changes in transition-state parameters with alteration in the reactant structure are interpreted as resulting from variation in a nitrile-forming transition state.

Original languageEnglish
Pages (from-to)6145-6148
Number of pages4
JournalJournal of the American Chemical Society
Volume110
Issue number18
Publication statusPublished - 1988 Dec 1

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Nitriles
Acetonitrile
Amines
Observation
Electrons
Kinetics
acetonitrile
picric acid
Direction compound
benzonitrile

ASJC Scopus subject areas

  • Chemistry(all)

Cite this

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title = "Eliminations from (E)-O-arylbenzaldoximes promoted by tertiary amines in acetonitrile. Effects of aryl substituents, base strength, and leaving group upon the nitrile-forming transition state",
abstract = "Elimination reactions of (E)-O-(2,4-dinitrophenyl)benzaldoximes (1) and (E)-O-picrylbenzaldoximes (2) with R3N in MeCN have been investigated. The reactions are quantitative, producing only benzonitriles and aryloxides. The observation of second-order kinetics, β = 0.43-0.81, and |β1g| = 0.39-0.73 is consistent with an E2 mechanism. For reactions of 1 with R3N in MeCN, the β and ρ values increased significantly with electron-withdrawing aryl substitutents and stronger bases respectively. The corresponding changes in the β and ρ values for 2 were in the same direction but much less. When the leaving group was changed from 2,4-dinitrophenoxide to picrate, however, β increased and ρ decreased. Changes in transition-state parameters with alteration in the reactant structure are interpreted as resulting from variation in a nitrile-forming transition state.",
author = "Bong-Rae Cho and Kim, {Kee Dong} and Lee, {Jong Chan} and Cho, {Nam Soon}",
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T1 - Eliminations from (E)-O-arylbenzaldoximes promoted by tertiary amines in acetonitrile. Effects of aryl substituents, base strength, and leaving group upon the nitrile-forming transition state

AU - Cho, Bong-Rae

AU - Kim, Kee Dong

AU - Lee, Jong Chan

AU - Cho, Nam Soon

PY - 1988/12/1

Y1 - 1988/12/1

N2 - Elimination reactions of (E)-O-(2,4-dinitrophenyl)benzaldoximes (1) and (E)-O-picrylbenzaldoximes (2) with R3N in MeCN have been investigated. The reactions are quantitative, producing only benzonitriles and aryloxides. The observation of second-order kinetics, β = 0.43-0.81, and |β1g| = 0.39-0.73 is consistent with an E2 mechanism. For reactions of 1 with R3N in MeCN, the β and ρ values increased significantly with electron-withdrawing aryl substitutents and stronger bases respectively. The corresponding changes in the β and ρ values for 2 were in the same direction but much less. When the leaving group was changed from 2,4-dinitrophenoxide to picrate, however, β increased and ρ decreased. Changes in transition-state parameters with alteration in the reactant structure are interpreted as resulting from variation in a nitrile-forming transition state.

AB - Elimination reactions of (E)-O-(2,4-dinitrophenyl)benzaldoximes (1) and (E)-O-picrylbenzaldoximes (2) with R3N in MeCN have been investigated. The reactions are quantitative, producing only benzonitriles and aryloxides. The observation of second-order kinetics, β = 0.43-0.81, and |β1g| = 0.39-0.73 is consistent with an E2 mechanism. For reactions of 1 with R3N in MeCN, the β and ρ values increased significantly with electron-withdrawing aryl substitutents and stronger bases respectively. The corresponding changes in the β and ρ values for 2 were in the same direction but much less. When the leaving group was changed from 2,4-dinitrophenoxide to picrate, however, β increased and ρ decreased. Changes in transition-state parameters with alteration in the reactant structure are interpreted as resulting from variation in a nitrile-forming transition state.

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