Eliminations from (E)-O-arylbenzaldehyde oximes promoted by hydroxide in 60% aq. dimethyl sulphoxide. Mechanism and transition-state characteristics of nitrile-forming eliminations

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

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Abstract

Reactions of the (E)-O-arylbenzaldehyde oximes (1; Ar = 2,4-dinitrophenyl), (2; Ar = Ρ-nitrophenyl), and (3; Ar = phenyl) with OH- in 60% aq. DMSO have been investigated. The eliminations are quantitative, producing only benzonitriles and aryloxides. The observation of second-order kinetics, k2 OD-/k2 OH- = 1.15-1.84, and βig = -0.59 is consistent with an E2 mechanism. The Hammett Ρ and K2 OD- K2 OH values increased with poorer leaving groups. For a given substrate the kz OD- /k2 OH- value remained (within experimental error) roughly constant, in spite of changes in the β-aryl substituents. These changes in transition state parameters can be interpreted in terms of the differing nitrile-forming transition states involved.

Original languageEnglish
Pages (from-to)489-492
Number of pages4
JournalJournal of the Chemical Society, Perkin Transactions 2
Issue number5
Publication statusPublished - 1989 Dec 1

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ASJC Scopus subject areas

  • Chemistry(all)

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