Complexes of Pyrazolone Derivatives with Some Aromatic Compounds

F. Z. Gorfinkel

(Presented by Prof. L. P. Kulev, Doctor of Chemical Sciences)

In previous works we studied the complex-formation reaction of pyrazolone derivatives—antipyrine and pyramidon—with carboxylic acids of the aromatic series, with certain higher fatty acids, dibasic acids, and Na salts of carboxylic and aromatic sulfonic acids. All the indicated compounds form complexes with antipyrine and pyramidon of composition \(1:1\), \(2:1\). In most cases these complexes have the structure of ammonium salts [2]. Proceeding from the structure of antipyrine and pyramidon—the presence of the group \(-N-CH_3\) and, respectively, \(-N(CH_3)_2\)—we considered possible the chemical interaction of halobenzenes with antipyrine and pyramidon. It is known that organohalogen compounds of the benzene series with a halogen at a carbon atom of the benzene ring are difficult to subject to the action of alkalis, alcoholates, amines, and other compounds, but in the presence of metals they readily give up the halogen.

B. V. Tronov and M. I. Bardamova give an interesting explanation of this fact from the electronic point of view [1]. They suppose that the phenyl radical withdraws electrons from the halogen atom, owing to which a positive excess charge is formed on the halogen, which then withdraws electrons readily given up by the metal [1]:

\[ \mathrm{C_6H_5{:}X{:} + {:}Mg \longrightarrow (C_6H_5{:})^{-} + {:}X{:} + Mg^{+}} \]

If, however, instead of the valence electrons of a metal, which completely leave their atom, a pair of electrons of the amino nitrogen \(-N-CH_3\), \(-N(CH_3)_2\) is attracted to the halobenzene molecule, then the process is limited to complex formation. We studied the action of antipyrine and pyramidon on iodo-, bromo-, and chlorobenzene.

We also considered it interesting to determine the possibility of interaction of antipyrine and pyramidon with certain polynuclear hydrocarbons, in particular with diphenyl and diphenyl ether. If the complexes of antipyrine and pyramidon have the character of ammonium salts,

Table 1

Table 2

then in the reaction with diphenyl and with diphenyl ether, chemical interaction is hardly possible, apart from the manifestation of van der Waals forces (bonds of the order of \(0.1\)—\(1 \dfrac{\text{kcal}}{\text{mole}}\), with the formation of molecular complexes), similarly to complexes of urea with saturated hydrocarbons \([3, 4, 5]\). The starting compounds (antipyrine, pyramidon, diphenyl, halogenobenzenes, etc.) had constants corresponding to the literature data. The antipyrine—diphenyl and antipyrine—diphenyl ether complexes obtained by us may be assigned to molecular compounds; in this case the process of complex formation can proceed only through the manifestation of van der Waals forces.

Experimental Part

Preparation of complexes of antipyrine and pyramidon with halogenobenzenes. 3–5 g of antipyrine or pyramidon were mixed with 9–15 g of iodo-, bromo-, or chlorobenzene in a 75 ml flask fitted with a reflux air condenser. The mixture was heated on a glycerol bath at \(100\)—\(120^\circ\) for 2–2.5 hours. The precipitate that separated from the cooled solution was filtered off, washed with a small amount of ether, and dried in air. The compound obtained was analyzed for nitrogen content by Kjeldahl’s method and for halogen content by fusion with metallic sodium in a bomb. The molecular weight was determined cryoscopically from benzene. Solubility in various solvents (alcohol, ether, benzene, toluene, acetone) was also determined. To prove that no valence reaction of the amino groups \(-\mathrm{N}-\mathrm{CH}_3\), \(-\mathrm{N}=\mathrm{C}\mathrm{H}_3\) with halogenobenzenes occurs in the compound obtained, the presence of ionized halogen was also determined by Volhard’s method in a nitric-acid medium. Ionized halogen was not detected in the compounds obtained. On the basis of the experimental data obtained, it may be concluded that the complexes of antipyrine and pyramidon with chloro-, bromo-, and iodobenzenes have a composition of 1:1.

Preparation of complexes of antipyrine and pyramidon with diphenyl and diphenyl ether

The complexes of antipyrine and pyramidon with diphenyl and diphenyl ether were obtained from melts at \(65\)—\(80^\circ\). The compounds obtained were recrystallized from ether and analyzed for nitrogen content and for the solubility of the complexes in various solvents. The composition of the complexes was also determined.

Determination of the composition of the complex. The first compound obtained was dissolved in 40 ml of distilled water and boiled for 5 minutes; it was then cooled and the precipitated solid was filtered off, after first washing it several times with water. The precipitate was dried in air, weighed, and the melting point was determined. The data obtained are given in Table 2.

Conclusions

1. Complexes of antipyrine and pyramidon with iodo-, bromo-, and chlorobenzenes of composition 1:1 were obtained.
2. The possibility of complex formation of antipyrine and pyramidon with diphenyl and diphenyl ether has been demonstrated.

References

1. B. V. Tronov and M. N. Varlamova, Proceedings of Higher Educational Institutions. Chemistry and Chemical Technology, vol. 1, p. 34, 1959.

2. F. Z. Gorfinkel, Reports of the First All-Union Conference on the Chemistry of Organic Complex Compounds. Tomsk State University Press, 1959.

3. V. Hückel, Theoretical Foundations of Organic Chemistry. Moscow–Leningrad, 1955.

4. B. T. Brooks, S. V. Burd, S. S. Kurtz, and L. I. Schmerling, The Chemistry of Petroleum Hydrocarbons. Gostoptekhizdat, 1958.

5. Benesi and Hildebrand, J. Am. Chem. Soc., 63, 207, 1951.

6. G. B. Freidlin, Journal of Applied Chemistry, vol. 29, no. 6, 1956.