Issue 40, 2015
From the journal:

RSC Advances

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

D. Ivanova,ab   V. Deneva,a   D. Nedeltcheva,*a   F. S. Kamounah,c   G. Gergov,b   P. E. Hansen,c   S. Kawauchid  and  L. Antonova  

* Corresponding authors

a Institute of Organic Chemistry with Centre of Phytochemistry, Bulgarian Academy of Sciences, Acad. G. Bonchev str., bldg. 9, BG-1113 Sofia, Bulgaria
E-mail: dantonova@orgchm.bas.bg

b Faculty of Pharmacy, Medical University of Sofia, 2 Dunav str., BG-1000 Sofia, Bulgaria

c Department of Science, Systems and Models, Roskilde University, P.O. Box 260, DK-4000 Roskilde, Denmark

d Tokyo Institute of Technology, Department of Organic and Polymeric Materials, 2-12-1 O-okayama, Meguro-ku, Tokyo 152-8552, Japan

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.

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

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Article information

DOI
https://doi.org/10.1039/C5RA03653D
Article type
Paper
Submitted
01 Mar 2015
Accepted
24 Mar 2015
First published
24 Mar 2015
This article is Open Access
Creative Commons BY license

RSC Adv., 2015,5, 31852-31860

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

D. Ivanova, V. Deneva, D. Nedeltcheva, F. S. Kamounah, G. Gergov, P. E. Hansen, S. Kawauchi and L. Antonov, RSC Adv., 2015, 5, 31852 DOI: 10.1039/C5RA03653D

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