Tautomeric transformations of piroxicam in solution: a combined experimental and theoretical study

D Ivanova, V Deneva, D Nedeltcheva, Fadhil S. Kamounah, G Gergov, Poul Erik Hansen, S Kawauchi, L Antonov

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Abstract

Piroxicam tautomerism was studied in solution by using UV-Vis spectroscopy, NMR measurements and advanced chemometrics. It has been found that in ethanol and DMSO the enol-amide tautomer is present mainly as a sandwich type dimer. The addition of water leads to distortion of the aggregate and to gradual shift of the equilibrium towards the zwitterionic tautomer. Quantitative data for the aggregation and the tautomeric equilibria are presented. Quantum chemical calculations (M06-2X/TZVP) have been used to explain stability of the tautomers as a function of the solvent and concentration.
Original languageEnglish
JournalRSC Advances
Volume5
Issue number40
Pages (from-to)31852-31860
Number of pages9
ISSN2046-2069
DOIs
Publication statusPublished - 2015

Keywords

  • isotope effects
  • NMR
  • DFT calculations
  • piroxicam
  • dimer

Cite this

Ivanova, D., Deneva, V., Nedeltcheva, D., Kamounah, F. S., Gergov, G., Hansen, P. E., ... Antonov, L. (2015). Tautomeric transformations of piroxicam in solution: a combined experimental and theoretical study. RSC Advances, 5(40), 31852-31860. https://doi.org/10.1039/c5ra03653d