Abstract
The pKa values of a number of alkaloids in water or in aqueous ethanol have been measured by the potentiometric titration method: nuphleine — 4.59, 6.98; brevicolline — 5.17, 8.02; chelidonine — 6.40; sanguinarine — 7.32; chelerythrine — 7.53; stepharine — 8.48; d-pseudoephedrine — 9.49. For nuphleine and brevicolline, each of which has two nitrogen atoms capable of protonation, assignments have been made of pKa values to the corresponding atoms on the basis of the results of UV spectroscopy.
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Additional information
All-Union Scientific-Research Institute of Medicinal Plants, Moscow. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 337–341, May–June, 1984.
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Perel'son, M.E., Persiyanova, I.V., Semenova, T.S. et al. Ionization constants of a number of alkaloids used in medicine. Chem Nat Compd 20, 314–317 (1984). https://doi.org/10.1007/BF00575756
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DOI: https://doi.org/10.1007/BF00575756