Skip to content
BY-NC-ND 3.0 license Open Access Published by De Gruyter Open Access December 1, 2003

IR-spectral study of photoinduced tautomerization in 1,3-diphenyl-pyrazol-5-one

Bojidarka Ivanova, Atanas Tchapkanov, Michail Arnaudov and Ivan Petkov
From the journal Open Chemistry


The UV-photoinduced prototropic isomerization of 1,3-diphenyl pyrazol-5-one (DPhP) embedded in polyvinyl chloride (PVC) film is studied by means of difference in IR spectral analysis. The initially existing CH-form in non-irradiated compound is transformed to NH-form, and a hydrochloride salt is stabilized because of the photodegradation of the PVC. An additional comparative IR spectral study of DPhP in different solutions as well as of its hydrochloride salts in solid state is also carried out.

[1] J. Elguero, C. Marzin, A.R. Katritzky and P. Linda: The tautomerism of Heterocycles, Academic Press, New York, 1976. Search in Google Scholar

[2] J. Elguero, A.R. Katritzky and P. Linda: The tautomerism of Heterocycles, Academic Press, New York, 1999. Search in Google Scholar

[3] A.R. Katritzky, and A.C. Bolton: Tautomerism of Heterocycles, Suppl. 1, Academic Press, New York, 1976. Search in Google Scholar

[4] A.R. Katritzky and F.W. Maine: “The Tautomerism of the heteroaromatic Compounds with Five membered rings”, Tetrahedron, Vol. 20, (1964), pp. 299–314. in Google Scholar

[5] J. Elguero, R. Jacquier and G. Tarrago: “Recherches la serie des azoles. XXX-Structure des pyrazolones en solution: determination de l'equilibrre et comportement spectral des pyrazolones tautomeres”, Bulletin Soc. Chim. France, (1967), pp. 3780–3794. Search in Google Scholar

[6] A. Maquestiau, Y. Van Heverbeke and R. Jacquerye: “Tautomerie dans le serie des pyrazolones. Influence du milien sur l'equilibre prototropique des pyrazoline-5-ones N1 substituents”, Bull. Soc. Chim. Belg, Vol. 82, (1973), pp. 215–231. in Google Scholar

[7] J. Elguero: Comprehensive Heterocyclic Chemistry. A.R. Katritzky, C.W. Ress (Eds.), Pergamon Press, Oxford, (1984), Vol. 5, p. 167; b) R.N. Butler: Comprehensive Heterocyclic Chemistry, A.R. Katritzky, C.W. Ress and E.F.V. Scriven (Eds.), Pergamon Press, Oxford, (1996), Vol 3, p. 1. Search in Google Scholar

[8] D. Zeigan, E. Kleinpeter, H. Wilde and G. Mann: “13C NMR—Untersuchung der tautomerie und des substiturntenffrktes 4-substitutierter Pyrazolin-5-one”, Journal f. Praktische Chemie, Vol. 323, (1981), pp. 188–198. in Google Scholar

[9] T. Nishiwaki and K. Kondo: “Studies on Heterocyclic Chemistry Part XII. Tautomerizm of α-(5-oxo-Δ3-isoxazolin-4-yl)benzylphosphonates”, Journal of Chemical Society, Perkin Transitions I, (1972), pp. 90–92. in Google Scholar

[10] D.S. Iyengar, K.K. Prasad and R.V. Venkataratnam: “1-Heteroarylpyrazoles. Stabilization of the 5-hydroxy tautomeric form by an a-nitrogen atom and effect on spectral properties”, Tetrahedron Letters, Vol. 37, (1972), pp. 3937–3940. in Google Scholar

[11] G.A. Newman and P.J.S. Pauwels: “Pyrazolin-5-one tautomerism. II. Effect of 3-substituents”, Tetrahedron, Vol. 26, (1970), pp. 1571–1578 in Google Scholar

[12] C. Dardonvill, J. Elguero, I. Rozas and C. Fernandez-Castano: “Tautomerism of 1-(2′,4′-dinitrophenyl)-3-methyl-2-pyrazolin-5-one: theoretical calculations, solid and solution NMR studies and X-ray crystallography”, New Journal of Chemistry, Vol. 12, (1998), pp. 1421–1430. in Google Scholar

[13] A. Chapkanov and I. Petkov: “Spectral and photochemical behavior of some pyrazolones in solution, micelles and polymer films”, Analytical Laboratory, Vol. 7, (1988), pp. 143–147. Search in Google Scholar

[14] J. Maack, R.C. Ahuja, D. Mobius, H. Tachibana H and M. Matsumoto: “Molecular cis-trans switching in amphiphilic monolayers containing azobenzene moieties”, Thin Solid Films, Vol. 242, (1994), pp. 122–126. in Google Scholar

[15] F. Chick and N.T.M. Wilsmore: “Acetylketen: a Polymeride of Keten”, Journal of the Chemical Society, Vol. 93, (1908), pp. 946–950. Search in Google Scholar

[16] M.G. Arnaudov: “The influence of the medium on the infrared spectrum of selfassociated systems”, Internet Journal of Vibrational Spectroscopy, Vol. 5, (2001), section 3. Search in Google Scholar

[17] G. Varsanyi: Vibrational spectra of benzene derivatives, Akademia Kiado, Budapest, 1969. 10.1016/B978-0-12-714950-9.50007-7Search in Google Scholar

[18] M. Arnaudov and Y. Dimitriev: “Study of the structural transition in binary tellurite glasses by means of reduced infrared spectra”, Phys. Chem. Glasses, Vol. 42, (2001) pp. 99–102. Search in Google Scholar

[19] E. Spiner: “The Vibration Spectra and Structures of the Hydrochlorides of Aminopyridines”, Journal of Chemical Society, Vol. 3, (1962) pp. 3119–3126. in Google Scholar

Published Online: 2003-12-1
Published in Print: 2003-12-1

© 2003 Versita Warsaw

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Scroll Up Arrow