Double Bromides of Piperidine with Arsenic, Antimony, and Bismuth

P. V. Kristalev

(Presented by Prof. Dr. Chem. Sci. V. V. Tronov)

The present work is a continuation of the study of the complex-forming ability of the halides of As, Sb, and Bi with hydrohalide salts of organic bases. Interest in the study of these derivatives is aroused by the presence among them of such chemotherapeutic preparations as “bioquinol”—quinine iodobismuthate \[1\], “biodamine” \[2\]—urotropine iodobismuthate, “solusurmin” \[3\]—a complex of antimony and sodium gluconate, and others.

In the interaction of the bromides of As and Sb with the corresponding piperidine salt, using chloroform as solvent, the following compounds have been obtained and described in the literature:

\[ 2\,\mathrm{C_5H_{11}N}\cdot \mathrm{HBr}\cdot \mathrm{AsBr_3}\cdot \mathrm{CHCl_3}; \qquad 3\,\mathrm{C_5H_{11}N}\cdot \mathrm{HBr}\cdot 2\mathrm{AsBr_3}\cdot \mathrm{CHCl_3}; \]

\[ 2\,\mathrm{C_5H_{11}N}\cdot \mathrm{HBr}\cdot \mathrm{AsBr_3}; \qquad \mathrm{C_5H_{11}N}\cdot \mathrm{HBr}\cdot 2\mathrm{AsBr_3}\ [4]; \]

\[ 3\,\mathrm{C_5H_{11}N}\cdot \mathrm{HBr}\cdot 2\mathrm{SbBr_3}; \qquad 2\,\mathrm{C_5H_{11}N}\cdot \mathrm{HBr}\cdot \mathrm{SbBr_3}\cdot \mathrm{CHCl_3}\ [5]. \]

In the preceding communication \[6\], in the condensation of piperidine chlorides with the chlorides of As, Sb, and Bi, HCl served as the solvent (sp. gr. 1.17). In the present investigation the medium was 40% HBr. Since the magnitude of the dipole moment \[7\] of HBr (0.78) is less than that of CHCl₃ (1.05), it was to be expected that in an HBr medium the most stable and characteristic complex compounds would form without solvent molecules.

Moreover, the use of HBr eliminated the need to prepare the bromides of As, Sb, and Bi, since they were obtained by dissolving As₂O₃, Sb₂O₃, and Bi₂O₃. The composition, melting point, and analyses for Me³⁺ (As, Sb, Bi) and Br⁻ of the compounds obtained by us are summarized in Table 1. As and Sb were determined iodometrically, and bromide ion by the Volhard method. In Bi derivatives the bromide ion was not determined.

One of these compounds—\(2\mathrm{C_5H_{11}N}\cdot \mathrm{HBr}\cdot \mathrm{AsBr_3}\)—was obtained by P. P. Popov and V. F. Novik from \(2\mathrm{C_5H_{11}N}\cdot \mathrm{HBr}\cdot \mathrm{AsBr_3}\cdot \mathrm{CHCl_3}\) after drying the latter in vacuum at 90°.

All the complex compounds synthesized by us are stable in air and are hydrolyzed by water. Their resistance to hydrolysis increases in the series As, Sb, Bi; in the same order the melting points and the intensity of coloration increase, from colorless As derivatives to bright-yellow Bi derivatives. Recrystallization from mother liquor and from 40% HBr did not lead to a change in the composition of the compounds obtained—

Table 1

compounds, in contrast to works [8], carried out using \(\mathrm{CHCl_3}\) as solvent, and did not give compounds whose composition included either solvent or water.

Experimental Part¹⁾

1. Condensation of \(\mathrm{C_5H_{11}N\cdot HBr}\) with \(\mathrm{AsBr_3}\).
To a solution of 6 g of \(\mathrm{C_5H_{11}N\cdot HBr}\) in 7 ml of HBr \((d = 1.48)\), over 10 minutes a solution of 3.6 g of \(\mathrm{AsBr_3}\) in 30 ml of HBr was added (ratio of components \(\mathrm{C_5H_{11}N\cdot HBr:AsBr_3}=3.35\)). A precipitate in the form of small, colorless, thin needles appears 5–6 minutes after the solutions are combined. The crystals are separated from the mother liquor, washed with HBr, and dried in vacuum over solid KOH at room temperature. Their composition corresponds to the formula \(2\mathrm{C_5H_{11}N\cdot HBr\cdot AsBr_3}\).

2. To a solution of 5.5 g of \(\mathrm{AsBr_3}\) in 40 ml of HBr, over 5 minutes a solution of 1.1 g of \(\mathrm{C_5H_{11}N\cdot HBr}\) in 3 ml of HBr was added \((\mathrm{AsBr_3:C_5H_{11}N\cdot HBr}=2.22)\).

The precipitate appearing upon addition of the first drops of solution disappeared and soon separated out in the form of small colorless needles. The crystals separated from the mother liquor were washed with HBr and dried in vacuum over solid KOH at room temperature.

Composition: \(3\mathrm{C_5H_{11}N\cdot HBr\cdot 2AsBr_3}\).

3. Condensation of \(\mathrm{C_5H_{11}N\cdot HBr}\) with \(\mathrm{SbBr_3}\).
To a solution of 5.5 g of \(\mathrm{C_5H_{11}N\cdot HBr}\) in 6.5 ml of HBr, over 10 minutes a solution of 4.0 g of \(\mathrm{SbBr_3}\) in 25 ml of HBr was added \((\mathrm{C_5H_{11}N\cdot HBr:SbBr_3}=2.92)\). With the first drops of hydrobromide piperidine, a light-yellow precipitate began to separate. The crystals, in the form of thin long needles, separated from the mother liquor and washed with HBr, were dried in vacuum over solid KOH. Composition: \(2\mathrm{C_5H_{11}N\cdot HBr\cdot SbBr_3}\).

4. To a solution of 5.5 g of \(\mathrm{SbBr_3}\) in 30 ml of HBr, a solution of 1 g of \(\mathrm{C_5H_{11}N\cdot HBr}\) in 4 ml of HBr was slowly added \((\mathrm{SbBr_3:C_5H_{11}N\cdot HBr}=2.58)\). The precipitate separated slowly, and the solution was left for 24 hours for complete precipitation. The light-yellow, fluffy, thin needles of the crystalline precipitate were filtered from the mother liquor, washed on the filter with HBr, and dried in a vacuum desiccator over solid KOH. Composition: \(5\mathrm{C_5H_{11}N\cdot HBr\cdot 2SbBr_3}\).

5. Condensation of \(\mathrm{C_5H_{11}N\cdot HBr}\) with \(\mathrm{BiBr_3}\).
To a solution of 6 g of \(\mathrm{C_5H_{11}N\cdot HBr}\) in 7 ml of HBr, over 10 minutes a solution of 5.3 g of \(\mathrm{Bi_2O_3}\) in 15 ml of HBr was added \((\mathrm{C_5H_{11}N\cdot HBr:BiBr_3}=3.06)\).

¹⁾ The work was carried out with the participation of students V. A. Bukaev, Sh. Sh. Gubaidullin, O. K. Mlyatkovskii, and V. M. Sheker.

A copious precipitate in the form of thin yellow plates, precipitating upon addition of almost the entire solution of \(C_5H_{11}N\cdot HBr\), was separated from the mother liquor, washed with HBr, and dried in vacuum over KOH.

Bismuth was determined photocolorimetrically by the iodometric method [9]. The standard bismuth solution was prepared from \(Bi_2O_3\).

A weighed portion of \(Bi_2O_3\), 0.0860 g, in a 200 ml volumetric flask was dissolved in 10 ml \(H_2SO_4\) (1:10); 5 ml \(H_2SO_3\) (1:20) and 10 ml of 2% KJ solution were added, and the resulting colored solution was diluted to the mark. The concentration of the standard solution was 0.415 mg Bi in 1 ml.

To construct the calibration curve, a definite amount of the standard solution (from 1 to 45 ml), depending on the dilution, was taken; 2–8 ml \(H_2SO_4\) (1:10) and 1–5 ml of 2% KJ were added, and the solution in the volumetric flask was brought with water to 50 ml.

The intensity of the colored solutions was measured on an “FEK-2” photocolorimeter in a cuvette of 10 ml volume with a blue light filter. From the measurements of the optical density of the solutions, a calibration curve was constructed (Fig. 1).

Fig. 1

The composition of condensation product 5 \((5C_5H_{11}N\cdot HBr\cdot 2BiBr_3)\) was established from bismuth. From a weighed portion of the substance, 0.0966 g, according to the method for preparing the standard colored solutions, a solution of 100 ml volume was prepared. The color intensity of the solution was measured in the photocolorimeter.

The extinction of the resulting solution was 0.40, which corresponded, according to the calibration curve (Fig. 1), to a concentration of 0.244 mg Bi/ml, or 0.0244 g in 100 ml.

1. A solution of 2 g \(C_5H_{11}N\cdot HBr\) in 10 ml HBr was added over 10 minutes to a solution of 8.4 g \(Bi_2O_3\) in 30 ml HBr \((BiBr_3:C_5H_{11}N\cdot HBr = 2.8)\).

Upon addition of the first drops of the \(C_5H_{11}N\cdot HBr\) solution, a bright-yellow crystalline precipitate began to form; it was separated from the mother liquor, washed with HBr, and dried in vacuum over KOH.

Composition: \(2C_5H_{11}N\cdot HBr\cdot BiBr_3\).

From a weighed portion of the substance, 0.0625 g, the colored solution prepared by the above-described method had an extinction equal to 0.31, which corresponded according to the curve to 0.20 mg Bi, or 0.020 g in 100 ml.

Conclusions

1. Six complexes of the hydrobromide salt of piperidine with the bromides of As, Sb, and Bi were obtained, using hydrobromic acid as the solvent.

2. The use of hydrobromic acid as the solvent makes it possible to obtain a small number of complex compounds without inclusion of solvent and water molecules in their composition.

LITERATURE

1. Skvortsov V. I. Course of Pharmacology, 544, Medgiz, 1948.
2. Cherkes A. I. Handbook of Pharmacotherapy, 39, Medgiz, 1946.
3. Mashkovskii, Handbook of New Medicinal Preparations, 160, Medizdat, 1948.
4. Popov P. P. and Novik V. F. Uchenye zapiski TGU No. 5, 74, 1947.
5. Popov P. P., Sidorov V. A. Trudy TGU, 122, 40, 1952.

1. Popov P. P. and Kristalev P. V. Proceedings of TSU, 126, 133, 1954.
2. Hildebrand J. Solubility of Nonelectrolytes. 62, GONTI, 1938.
3. Popov P. P. Journal of General Chemistry, 19, 47, 1949.
4. Babko A. K., Pilipenko A. T. Colorimetric Analysis. Goskhimizdat, 76, 1951.