An experimental (flash vacuum pyrolysis) and theoretical study of the tautomerism of pyrazolinones at high temperatures

Abstract

Flash vacuum pyrolysis experiments were carried out between 500 and 800 °C on 3(5)-phenyl- and 3(5)-methyl-pyrazolinones and on 3(5)-methoxy-5(3)-phenylpyrazole. The origin of the isolated products (mainly indanone, hydroxyalkynes and α,β-unsaturated aldehydes) can be explained as arising from the hydroxy tautomers of pyrazolinones. Temperature effects on the tautomeric equilibrium of 1-phenyl-3-methylpyrazolinone in solution show that the percentage of the CH tautomer increases with the temperature. MP2 ab initio calculations on the model compound, pyrazolinone itself, have been used to rationalize these findings. The problem of the aromaticity of the four tautomers of pyrazolinone has been examined through Schleyer’s NICS (nuclear independent chemical shifts) calculations.

References

1. J. D. Pérez and G. I. Yranzo, J. Org. Chem., 1982, 47, 2221; D. Pérez and G. I. Yranzo, Bull. Soc. Chim. Fr., 1985, 473.
2. J. D. Pérez, G. I. Yranzo and L. M. Phagouapé, Bull. Soc. Chim. Fr., 1986, 129.
3. J. D. Pérez and and L. M. Phagouapé, Int. J. Chem. Kinet., 1987, 19, 571; J. D. Pérez and and L. M. Phagouapé, Ibid., 1988, 20, 217; J. D. Pérez and and L. M. Phagouapé, Ibid., 1988, 20, 603; J. D. Pérez and and L. M. Phagouapé, Ibid, 1989, 21, 227.
4. J. D. Pérez, G. I. Yranzo, M. A. Ferraris, R. M. Claramunt and J. Elguero, Tetrahedron, 1988, 44, 6429.
5. J. D. Pérez and G. I. Yranzo, J. Anal. Appl. Pyrol., 1989, 16, 165.
6. J. D. Pérez, G. I. Yranzo and J. Elguero, J. Fluorine Chem., 1993, 63, 271.
7. E. L. Moyano, G. I. Yranzo and J. Elguero, J. Org. Chem., 1998, 63, 8188.
8. J. Elguero, C. Marzin, A. R. Katritzky and P. LindaThe Tautomerism of Heterocycles, Academic Press, New York, 1976, p. 266; New edition: Advances in Heterocyclic Chemistry, 1998, in the press.
9. Vogel's Textbook of Practical Organic Chemistry, Fifth Edition, 1989, (a)p. 1050; (b)p. 433.
10. V. F. Matinov and I. B. Belov, J. Gen. Chem. USSR (Engl. Transl.), 1963, 33, 1079.
11. K. von Auwers and W. Mauss, J. Prakt. Chem., 1925, 110, 204.
12. Aldrich NMR FT Catalog 1, 1993, 2, 808 C.
13. K. Sonogashira, Y. Toda and N. Hagihara, Tetrahedron Lett., 1975, 4467.
14. Aldrich NMR FT Catalog 1, 1993, 2, 926 C.
15. A. I. Meyers and E. W. Collington, J. Am. Chem. Soc., 1970, 92, 6676.
16. Aldrich NMR FT Catalog 1, 1993, 2, 508 C.
17. Varian-NMR Spectra Catalog, 1966, 1, 60.
18. S. Danishefsky and M. Bednarski, Tetrahedron Lett., 1983, 24, 3451.
19. M. J. Frisch, G. W. Trucks, H. B. Schlegel, P. M. W. Gill, B. G. Johnson, M. A. Robb, J. R. Cheeseman, T. A. Keith, G. A. Petersson, J. A. Montgomery, K. Raghavachari, M. A. Al-Laham, V. G. Zakrzewski, J. V. Ortiz, J. B. Foresman, C. Y. Peng, P. Y. Ayala, M. W. Wong, J. L. Andres, E. S. Replogle, R. Gomperts, R. L. Martin, D. J. Fox, J. S. Binkley, D. J. Defrees, J. Baker, J. P. Stewart, M. Head-Gordon, C. Gonzalez and J. A. Pople, Gaussian, Inc., Pittsburgh, PA, 1995.
20. P. C. Hariharan and J. A. Pople, Theor. Chim. Acta, 1973, 28, 213.
21. C. Møller and M. S. Plesset, Phys. Rev., 1934, 46, 618.
22. R. F. W. Bader, Atoms in Molecules. A Quantum Theory, Oxford University, New York, 1990.
23. F. London, J. Phys. Radium (Paris), 1937, 8, 397; R. Ditchfield, Mol. Phys., 1974, 27, 789; D. B. Chesnut, ‘Ab Initio Calculations of NMR Chemical Shielding’ in Ann. Rep. NMR Spectrosc., 1994, 29, 71; R. J. Iuliucci, J. C. Facelli, D. W. Alderman and D. M. Grant, J. Am. Chem. Soc., 1995, 117, 2336; J. R. Cheeseman, G. W. Trucks, T. A. Keith and M. J. Frisch, J. Chem. Phys., 1996, 104, 5497.
24. R. F. C. Brown, Pyrolytic Methods in Organic Chemistry, Academic Press, New York, 1980, p. 164.
25. R. F. C. Brown, Pyrolytic Methods in Organic Chemistry, Academic Press, New York, 1980, p. 55.
26. D. Groschl and H. Meier, Liebigs Ann. Chem., 1995, 441.
27. P. Bouchet, J. Elguero, R. Jacquier and J. M. Pereillo, Bull. Soc. Chim. Fr., 1974, 291.
28. O. G. Parchment, D. V. S. Green, P. J. Taylor and I. H. Hillier, J. Am. Chem. Soc., 1993, 115, 2352.
29. M. Cao, B. J. Teppen, D. M. Miller, J. Pranata and L. Schäfer, J. Phys. Chem., 1994, 98, 11353.
30. F. J. Luque, J. M. López-Bes, J. Cemeli, M. Aroztegui and M. Orozco, Theor. Chim. Acta, 1997, 96, 105.
31. S. Ono, K. Okazaki, M. Sakurai and Y. Inoue, J. Phys. Chem. A, 1997, 101, 3769.
32. C. Dardonville, J. Elguero, I. Rozas, C. Fernández-Castaño, C. Foces-Foces and I. Sobrados, New. J. Chem., 1998, in the press.
33. M. W. Wong, Chem. Phys. Lett., 1996, 256, 391; D. A. Estrin, L. Paglieri, G. Corongiu and E. Clementi, J. Phys. Chem., 1996, 100, 8701.
34. J. Deschamps, J. Arriau and P. Parmentier, Tetrahedron, 1971, 27, 5779.
35. A. Maquestiau, Y. van Haverbeke and A. Bruyere, Bull. Soc. Chim. Belg., 1973, 82, 757.
36. J. L. M. Abboud, P. Cabildo, T. Cañada, J. Catalan, R. M. Claramunt, J. L. G. de Paz, J. Elguero, H. Homan, R. Notario, C. Toiron and G. I. Yranzo, J. Org. Chem., 1992, 57, 3938.
37. A. El Hammadi, M. El Mouhtadi, R. Notario, J. L. M. Abboud and J. Elguero, J. Chem. Res. (S), 1995, 172.
38. A. El Hammadi, M. El Mouhtadi, R. Notario, A. Werner and J. Elguero, J. Chem. Soc., Perkin Trans. 2, 1995, 379.
39. A. R. Katrizky, P. Barczynski, G. Musumarra, D. Pisano and M. Szafran, J. Am. Chem. Soc., 1989, 111, 7; P. von R. Schleyer, P. K. Freeman, H. Jiao and B. Goldfuss, Angew. Chem., Int. Ed. Engl., 1995, 34, 337.
40. P. von R. Schleyer, C. Maerker, A. Dransfeld, H. Jiao and N. J. R. van Eikema-Hommes, J. Am. Chem. Soc., 1996, 118, 6317.