Abstract
The parameters of the acid-base and tautomeric equilibria of the E (syn) isomers of 1-methyl-substituted benzimidazole-2-carbaldehyde oxime, imidazole-2-carbaldehyde oxime, Δ2-imidazoline-2-carbaldehyde oxime, and Δ2-pyrazoline-3-carbaldehyde oxime in aqueous solutions at 25°C have been determined by a potentiometric method using model compounds. The tautomeric ratio (zwitterion)/(uncharged form) rises in parallel with an increase in the basicity of the parent heterocycle. Unlike known heterocyclic aldoximes, 1-methyl-Δ2-imidazoline-2-carboxaldehyde oxime exists in the zwitterionic form.
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Additional information
For Communication III, see [1].
The system of numerical indices to denote the microconstants is similar to that adoptedby Edsall et al. [2].
Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1181–1185, September, 1973.
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Somin, I.N., Shapranova, N.I. & Kuznetsov, S.G. Oximes of azolecarbaldehydes and Δ2-azolinecarbaldehydes and their derivatives. Chem Heterocycl Compd 9, 1074–1077 (1973). https://doi.org/10.1007/BF00474774
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DOI: https://doi.org/10.1007/BF00474774