Complex Compounds of Hydroquinone and Resorcinolquinoline with Mineral Salts

I. I. Molodykh and A. E. Lapina

Introduction

Different metals possess unequal capacity for complex formation. Complex compounds in which the role of the central atom would be played by an alkali metal occur in considerably smaller numbers than analogous compounds with atoms of heavy metals in the nucleus. When the electrochemical series is considered, it is found that the tendency to form complex compounds increases with decreasing electropositivity, which is known to depend on atomic volume. In the alkali metals the electropositivity is greatest, and therefore they tend to pass directly into the ionic state; on the contrary, metals with a small atomic volume (Co, Ni, Cu, Ag, Au, Pt, etc.) require, in order to pass into the ionic state, an increase of the latter, which is achieved through formation of a complex. Complex compounds vary greatly in stability. Alongside extremely unstable ones, there also exist such compounds whose decomposition into their constituent components requires considerable effort. The stability of complex compounds is of great importance in analytical chemistry for the qualitative detection and quantitative determination of the corresponding metals. There is no doubt that the study of compounds formed by various organic substances with mineral salts is of ever increasing importance for the development of analytical methods.

Investigations in the field of compounds of tetrasubstituted ammoniums with mineral salts have yielded a sufficient number of similar complexes, but all of them, being compounds more or less soluble in water, have no practical application. The purpose of the present work was an attempt to obtain ternary complex compounds having poor solubility.

As objects for investigation there served complex compounds of mineral salts with more complicated tertiary cyclic amines, namely with hydroquinone- and resorcinolquinoline. For the complex compounds obtained, several structural formulas may be proposed. Of these, structure I may be regarded as the most probable.

In favor of such a structure speaks the fact of the existence of the salts $C_9H_7N \cdot HgCl_2$ and $C_9H_7N \cdot CdCl_2$, obtained as a result of the combination of quinoline with $HgCl_2$ and $CdCl_2$. The structure of these complex salts may be represented in the form of the formula shown on the following page.

It is very probable that the same structure is retained when mineral salts are added to hydroquinonequinoline. It should be noted that compounds of hydroquinone with mineral salts also exist, but in them the starting substances are taken in entirely different proportions than in complexes with hydroquinonequinoline.

\[ \text{[Structural formulas of coordination compounds involving quinoline, hydroquinone, and metal chlorides are shown.]} \]

The formula stated above is all the more probable because nitrogen in ammonia and amines enters extremely readily into a complex bond with metals, forming compounds of considerably greater strength than those in which the complex bond is effected through oxygen. The inner coordination sphere is a cation consisting of the metal and the organic part, while the outer sphere is a simple anion, \(\mathrm{Cl}'\).

\[ \begin{array}{r} \mathrm{Cl} - \left[\, \mathrm{Me}\ldots \mathrm{NC_9H_7}\ldots \mathrm{C_6H_4(OH)_2}\ldots \mathrm{C_9H_7N}\ldots \mathrm{Me} \,\right] - \mathrm{Cl} \\ \mathrm{Cl} - \left[\, \mathrm{Me}\ldots \mathrm{NC_9H_7}\ldots \mathrm{C_6H_4(OH)_2}\ldots \mathrm{C_9H_7N}\ldots \mathrm{Me} \,\right] - \mathrm{Cl} \end{array} \]

METHOD OF WORK

The starting substances—hydroquinonequinoline and the mineral salts—were ground, after which saturated solutions of them were prepared. Alcohol or ether is used as the solvent for hydroquinonequinoline; for the mineral salts, alcohol or water. In obtaining the complexes, various stoichiometric ratios of the component parts were tested, as a result of which it was established that their combination occurs in the ratio of one molecule of hydroquinonequinoline to two molecules of the mineral salt. The complexes were obtained by mixing an alcoholic or ethereal solution of hydroquinonequinoline with an alcoholic or aqueous solution of the mineral salts. The product obtained was filtered on a Büchner funnel, washed with alcohol and ether, dried in a desiccator, and then subjected to analysis. Determinations were carried out for the metal and the halide.

For greater confidence in the results obtained by analysis, one combustion was carried out. In addition to the experiments with hydroquinonequinoline, a series of experiments was performed with resorcinolquinoline. The latter is oxidized with more difficulty than hydroquinonequinoline, which can be explained by the meta-position of the hydroxyl groups in the resorcinol molecule. Melting points were determined in capillaries.

EXPERIMENTAL PART

Preparation of the starting substance. The starting substance for obtaining ternary complex compounds in the present work was hydroquinonequinoline, prepared by Hosck’s method by fusing one molecule of hydroquinone with two molecules of quinoline at 100°. The hydroquinonequinoline obtained, after recrystallization from alcohol, was a white crystalline substance, insoluble in water and readily soluble in alcohol, ether, benzene, toluene, and also in mineral acids, which decompose it into its constituent parts. In the dry state, and also in the ternary complex compounds formed by it, it is more stable. Oxidizing agents convert one constituent part of the molecule, namely hydroquinone, into quinone. On heating with water it undergoes cleavage. It has a melting point of 98.5°.

With mineral salts the following complexes were obtained and studied:

1. \((\mathrm{C}_9\mathrm{H}_7\mathrm{N})_2\,\mathrm{C}_6\mathrm{H}_4(\mathrm{OH})_2 \cdot 2\mathrm{CdI}_2\) . . . . . . . . . . . . . white
2. \((\mathrm{C}_9\mathrm{H}_7\mathrm{N})_2\,\mathrm{C}_6\mathrm{H}_4(\mathrm{OH})_2 \cdot 2\mathrm{CdCl}_2\) . . . . . . . . . . . white
3. \((\mathrm{C}_9\mathrm{H}_7\mathrm{N})_2\,\mathrm{C}_6\mathrm{H}_4(\mathrm{OH})_2 \cdot 2\mathrm{CuCl}_2\) . . . . . . . . brown
4. \((\mathrm{C}_9\mathrm{H}_7\mathrm{N})_2\,\mathrm{C}_6\mathrm{H}_4(\mathrm{OH})_2 \cdot 2\mathrm{CoCl}_2\) . . . . . . . . blue
5. \((\mathrm{C}_9\mathrm{H}_7\mathrm{N})_2\,\mathrm{C}_6\mathrm{H}_4(\mathrm{OH})_2 \cdot 2\mathrm{HgCl}_2\) . . . . . . . . white
6. \((\mathrm{C}_9\mathrm{H}_7\mathrm{N})_2\,\mathrm{C}_6\mathrm{H}_4(\mathrm{OH})_2 \cdot 2\mathrm{ZnCl}_2\) . . . . . . . . white
7. \((\mathrm{C}_9\mathrm{H}_7\mathrm{N})_2\,\mathrm{C}_6\mathrm{H}_4(\mathrm{OH})_2 \cdot 2\mathrm{SnCl}_2\) . . . . . . . . white
8. \((\mathrm{C}_9\mathrm{H}_7\mathrm{N})_2\,\mathrm{C}_6\mathrm{H}_4(\mathrm{OH})_2 \cdot 2\mathrm{AlCl}_3\) . . . . . . . . white
9. \((\mathrm{C}_9\mathrm{H}_7\mathrm{N})_2\,\mathrm{C}_6\mathrm{H}_4(\mathrm{OH})_2 \cdot 2\mathrm{CrCl}_3\) . . . . . . . . green
10. \((\mathrm{C}_9\mathrm{H}_7\mathrm{N})_2\,\mathrm{C}_6\mathrm{H}_4(\mathrm{OH})_2 \cdot 2\mathrm{FeCl}_3\) . . . . . . . . brown
11. \((\mathrm{C}_9\mathrm{H}_7\mathrm{N})_2\,\mathrm{C}_6\mathrm{H}_4(\mathrm{OH})_2 \cdot 2\mathrm{BiCl}_3\) . . . . . . . . white

1. COMPLEX COMPOUNDS OF HYDROQUINONEQUINOLINE WITH SALTS OF DIVALENT METALS

No. 1. Complex \((\mathrm{C}_9\mathrm{H}_7\mathrm{N})_2\,\mathrm{C}_6\mathrm{H}_4(\mathrm{OH})_2 \cdot 2\mathrm{CdI}_2\)

It is obtained by mixing an alcoholic solution of hydroquinonequinoline with an aqueous solution of cadmium iodide. It precipitates as a white crystalline precipitate. The crystals are fairly large, well formed, and lustrous. It is sparingly soluble in cold water, readily soluble in hot water and in mineral acids. M.p. 226°.

Analysis of the complex

The complex is stable; in air at room temperature it keeps well.

No. 2. Complex \((\mathrm{C_9H_7N})_2\,\mathrm{C_6H_4(OH)_2}\cdot 2\mathrm{CdCl_2}\).

It separates in the form of a white crystalline precipitate when an alcoholic solution of hydroquinonequinoline is mixed with an aqueous solution of \(\mathrm{CdCl_2}\). It differs from complex No. 1 in that the crystals are smaller; they dissolve in the same solvents as complex No. 1. It dissolves in water better than in alcohol. M.p. \(268^\circ\).

Analysis of the complex.

Determination of chlorine

\((\text{as } \mathrm{AgCl}.)\)

Determination of cadmium

\((\text{as } \mathrm{CdSO_4})\)

Percentage content of chlorine.

Percentage content of cadmium.

Determination of carbon and hydrogen by the combustion method.

Percentage content of carbon and hydrogen.

Nitrogen was not determined.

No. 3. Complex \((\mathrm{C_9H_7N})_2\,\mathrm{C_6H_4(OH)_2}\cdot 2\mathrm{CuCl_2}\).

It is obtained only from an ethereal solution of hydroquinonequinoline and alcoholic \(\mathrm{CuCl_2}\). It has a brown color and a sharp odor. M.p. \(242^\circ\). It is unstable—under the action of water it changes color to golden-yellow, shows a lower chlorine content¹ and has a melting point of \(236^\circ\). On standing in air, the appearance in the precipitate of reddish-brown needles with a green luster is observed. The complex is decomposed by water (by acidified water it is decomposed more rapidly).

Analysis of the complex.

Determination of chlorine:

\((\text{as } \mathrm{AgCl})\)

Determination of copper:

\((\text{as } \mathrm{CuO})\)

Percentage content of chlorine.

Found 22.10%;
calculated 22.5%.

Percentage content of copper.

Found 20.13%;
calculated 20.00%.

No. 4. Complex \((\mathrm{C}_9\mathrm{H}_7\mathrm{N})_2\,\mathrm{C}_6\mathrm{H}_4(\mathrm{OH})_2 \cdot 2\mathrm{CoCl}_2\).

It is obtained only from saturated alcoholic solutions of both hydroquinonequinoline and \(\mathrm{CoCl}_2\). It separates in the form of small light-blue, well-formed crystals, some of which decompose at once. Those separated from the mother liquor and dried, however, keep for a long time without changing. It melts at \(245^\circ\) with decomposition. It is decomposed by water, and likewise by mineral acids.

Analysis of the complex.

Percentage content of chlorine

Found 22.94%;
calculated 22.87%.

Percentage content of cobalt

Found 18.82%;
calculated 18.75%.

No. 5. Complex \((\mathrm{C}_9\mathrm{H}_7\mathrm{N})_2\,\mathrm{C}_6\mathrm{H}_4(\mathrm{OH})_2 \cdot 2\mathrm{HgCl}_2\).

It can be obtained from an alcoholic solution of hydroquinonequinoline and an aqueous solution of mercuric chloride. It has the appearance of a white, very fine precipitate. It is only sparingly soluble in water, even on boiling; in alcohol and ether it is almost completely insoluble. M.p. \(218^\circ\).

It was tested by Dr. Lipskaya as a pharmaceutical preparation in the treatment of certain weeping eruptions. It gave very good results.

Analysis of the complex.

Percentage content of chlorine

Found 15.65%.
Calculated 15.58%.

Percentage content of mercury

Found 44.10%.
Calculated 43.97%.

No. 6. Complex \((\mathrm{C}_9\mathrm{H}_7\mathrm{N})_2\mathrm{C}_6\mathrm{H}_4(\mathrm{OH})_2 \cdot 2\mathrm{ZnCl}_2\).

It is obtained in the form of transparent white crystals when concentrated (alcoholic) solutions of hydroquinonequinoline and zinc chloride are mixed. It dissolves in slightly acidified water and has a melting point of \(252^\circ\).

Analysis of the complex

No. 7. Complex \((\mathrm{C}_9\mathrm{H}_7\mathrm{N})_2\mathrm{C}_6\mathrm{H}_4(\mathrm{OH})_2 \cdot 2\mathrm{SnCl}_2\).

It is formed as a white precipitate when alcoholic solutions of the components are mixed. In water it dissolves with decomposition. It has a melting point of \(258^\circ\).

Analysis of the complex

2. COMPLEX COMPOUNDS OF HYDROQUINONEQUINOLINE WITH SALTS OF TRIVALENT METALS

No. 8. Complex \((\mathrm{C}_9\mathrm{H}_7\mathrm{N})_2\mathrm{C}_6\mathrm{H}_4(\mathrm{OH})_2 \cdot 2\mathrm{AlCl}_3\).

It is obtained in the form of needle-like white crystals when alcoholic solutions of hydroquinonequinoline and aluminum chloride are mixed. It crystallizes after 30 hours, after evaporation of a considerable amount of solvent. The substance is a greasy mass. It dissolves well in water, less in alcohol, and is completely insoluble in ether. It melts at a temperature of \(42^\circ\).

Analysis of the complex

Percentage content
of chlorine

Found 33.6%.
Calculated 33.5%.

Percentage content
of aluminum

Found 8.45%.
Calculated 8.50%.

No. 9. Complex \((\mathrm{C}_9\mathrm{H}_7\mathrm{N})_2\,\mathrm{C}_6\mathrm{H}_4(\mathrm{OH})_2 \cdot 2\,\mathrm{CrCl}_3\).

It is formed when alcoholic solutions of the constituent parts are mixed and most of the solvent is subsequently evaporated. A green, gelatinous substance. It dissolves readily in water, likewise in alcohol; in ether it dissolves less well. Crystallizes after 70 hours. M.p. \(35^\circ\).

Analysis of the complex

Determination of chlorine

Sample \(0.2452\ \mathrm{g}\),
weight of \(\mathrm{AgCl}\) \(0.3146\ \mathrm{g}\),
weight of \(\mathrm{Cl}\) \(0.0778\ \mathrm{g}\).

Percentage content
of chlorine

Found 31.72%.
Calculated 31.66%.

Determination of chromium

(as \(\mathrm{Cr}_2\mathrm{O}_3\))

Sample \(0.2748\ \mathrm{g}\),
weight of \(\mathrm{Cr}_2\mathrm{O}_3\) \(0.0616\ \mathrm{g}\),
weight of \(\mathrm{Cr}\) \(0.04210\ \mathrm{g}\).

Percentage content
of chromium

Found 15.34%.
Calculated 15.18%.

No. 10. Complex \((\mathrm{C}_9\mathrm{H}_7\mathrm{N})_2\,\mathrm{C}_6\mathrm{H}_4(\mathrm{OH})_2 \cdot 2\,\mathrm{FeCl}_3\).

It is formed both in ether–alcohol and in aqueous–alcoholic solutions as a viscous dark-brown mass. It almost does not crystallize. Readily soluble in water, less well in alcohol and ether. M.p. \(30^\circ\).

Analysis of the complex

Determination of chlorine

Sample \(0.2112\ \mathrm{g}\),
weight of \(\mathrm{AgCl}\) \(0.2491\ \mathrm{g}\),
weight of \(\mathrm{Cl}\) \(0.06152\ \mathrm{g}\).

Percentage content
of chlorine

Found 30.6%.
Calculated 30.72%.

Determination of iron

(as \(\mathrm{Fe}_2\mathrm{O}_3\))

Sample \(0.3568\ \mathrm{g}\),
weight of \(\mathrm{Fe}_2\mathrm{O}_3\) \(0.0827\ \mathrm{g}\),
weight of \(\mathrm{Fe}\) \(0.0578\ \mathrm{g}\).

Percentage content
of iron

Found 16.20%.
Calculated 16.13%.

No. 11. Complex \((\mathrm{C}_9\mathrm{H}_7\mathrm{N})_2\,\mathrm{C}_6\mathrm{H}_4(\mathrm{OH})_2 \cdot 2\,\mathrm{BiCl}_3\).

It separates from alcoholic solutions of hydroquinonequinoline and bismuth chloride¹ in the form of a white powdery precipitate. In water it is difficultly soluble even on heating. It dissolves in acids; in alcohol worse, in ether almost not at all. M.p. \(285^\circ\).

¹ To avoid hydrolysis, the solution was acidified.

Analysis of the complex

Determination of chlorine

Sample: 0.1236 g,
weight of AgCl: 0.0962 g,
weight of Cl: 0.0238 g.

Percentage content of chlorine

Found: 21.6%.
Calculated: 21.34%.

Determination of bismuth

(as Bi₂O₃)

Sample: 0.2340 g,
weight of Bi₂O₃: 0.1095 g,
weight of Bi: 0.0982 g.

Percentage content of bismuth

Found: 41.98%.
Calculated: 41.72%.

In addition to the complexes described above, complex salts of hydroquinonequinoline with Pb(NO₃)₂, SnCl₄, CuBr₂, and CuSO₄ were obtained, but no investigation of these was carried out.

3. COMPLEX COMPOUNDS OF RESORCINOLQUINOLINE WITH MINERAL SALTS

Resorcinolquinoline, like hydroquinonequinoline, was obtained by the method of Hosck. It is a white crystalline substance, readily soluble in water and alcohol, with a melting point of 85°.

The following complexes were obtained with resorcinolquinoline:

1. $(\mathrm{C}_9\mathrm{H}_7\mathrm{N})_2\mathrm{C}_6\mathrm{H}_4(\mathrm{OH})_2 \cdot \mathrm{CdCl}_2$ . . . . . . . . white
2. $(\mathrm{C}_9\mathrm{H}_7\mathrm{N})_2\mathrm{C}_6\mathrm{H}_4(\mathrm{OH})_2 \cdot 2\mathrm{HgCl}_2$ . . . . . . . . white
3. $(\mathrm{C}_9\mathrm{H}_7\mathrm{N})_2\mathrm{C}_6\mathrm{H}_4(\mathrm{OH})_2 \cdot 2\mathrm{CoCl}_2$ . . . . . . . . blue
4. $(\mathrm{C}_9\mathrm{H}_7\mathrm{N})_2\mathrm{C}_6\mathrm{H}_4(\mathrm{OH})_2 \cdot 2\mathrm{BiCl}_3$ . . . . . . . . white
5. $(\mathrm{C}_9\mathrm{H}_7\mathrm{N})_2\mathrm{C}_6\mathrm{H}_4(\mathrm{OH})_2 \cdot 2\mathrm{CuCl}_2$ . . . dark olive-colored

No. 1. Complex $(\mathrm{C}_9\mathrm{H}_7\mathrm{N})_2\mathrm{C}_6\mathrm{H}_4(\mathrm{OH})_2 \cdot 2\mathrm{CdCl}_2$.

It is obtained in the same way as the complex of cadmium chloride with hydroquinonequinoline. The properties, solubility, and color are the same; the only difference is in the melting point, which in this case is 282°.

Analysis of the complex

Analysis for chlorine

Sample: 0.3016 g,
weight of AgCl: 0.2381 g,
weight of Cl: 0.0588 g.

Percentage content of chlorine

Found: 19.41%.
Calculated: 19.26%.

Analysis for cadmium

(as CdSO₄)

Sample: 0.1489 g,
weight of CdSO₄: 0.0837 g,
weight of Cd: 0.0451 g.

Percentage content of cadmium

Found: 30.25%.
Calculated: 30.48%.

No. 2 Complex $(\mathrm{C}_9\mathrm{H}_7\mathrm{N})_2\mathrm{C}_6\mathrm{H}_4(\mathrm{OH})_2 \cdot 2\mathrm{HgCl}_2$.

The method of preparation and the properties are the same as for the corresponding complex of hydroquinonequinoline. Melting point 218°.

Analysis of the Complex

Determination of chlorine

Sample: 0.3434 g,
weight of AgCl: 0.2790 g,
weight of Cl: 0.0539 g.

Percentage content of chlorine

Found: 15.71%.
Calculated: 15.58%.

Determination of mercury

(as HgS)

Sample: 0.2130 g,
weight of HgS: 0.1139 g,
weight of Hg: 0.0994 g.

Percentage content of mercury

Found: 43.90%.
Calculated: 43.97%.

No. 3. Complex \((\mathrm{C}_9\mathrm{H}_7\mathrm{N})_2\,\mathrm{C}_6\mathrm{H}_4(\mathrm{OH})_2 \cdot 2\mathrm{CoCl}_2\).

As in the formation of the cobalt complex with hydroquinone-quinoline, an incomplete combination of the substances is observed. It dissolves in water and with greater difficulty in alcohol and ether. Melting point: 280°.

Analysis of the Complex

Determination of chlorine

Sample: 0.1988 g,
weight of AgCl: 0.1846 g,
weight of Cl: 0.0457 g.

Percentage content of chlorine

Found: 23%.
Calculated: 22.87%.

Determination of cobalt

(as CoSO₄)

Sample: 0.1420 g,
weight of CoSO₄: 0.0711 g,
weight of Co: 0.0271 g.

Percentage content of cobalt

Found: 19.10%.
Calculated: 18.75%.

No. 4. Complex \((\mathrm{C}_9\mathrm{H}_7\mathrm{N})_2\,\mathrm{C}_6\mathrm{H}_4(\mathrm{OH})_2 \cdot 2\mathrm{BiCl}_3\).

In its properties it does not differ from the corresponding complex with hydroquinone-quinoline; only the melting point is higher, namely 300°.

Analysis of the Complex

Determination of chlorine

Sample: 0.2673 g,
weight of AgCl: 0.2340 g,
weight of Cl: 0.0580 g.

Percentage content of chlorine

Found: 21.73%.
Calculated: 21.34%.

Determination of bismuth

(as Bi₂O₃)

Sample: 0.2178 g,
weight of Bi₂O₃: 0.10200 g,
weight of Bi: 0.0914 g.

Percentage content of bismuth

Found: 42.00%.
Calculated: 41.72%.

No. 5. Complex \((\mathrm{C}_9\mathrm{H}_7\mathrm{N})_2 \mathrm{C}_6\mathrm{H}_4(\mathrm{OH})_2 \cdot 2\,\mathrm{CuCl}_2\).

The complex is obtained under the same conditions as with hydroquinonequinoline, i.e., by mixing an ethereal solution of resorcinolquinoline with an alcoholic solution of \(\mathrm{CuCl}_2\). It separates as an olive-colored precipitate. It is decomposed by water. Melting point \(255^\circ\).

Analysis of the complex

Determination of chlorine

Sample \(0.1982\) g,
weight of \(\mathrm{AgCl}\) \(0.182\) g,
weight of \(\mathrm{Cl}\) \(0.0446\) g.

Determination of copper

Sample \(0.1402\) g,
weight of \(\mathrm{CuO}\) \(0.0356\) g,
weight of \(\mathrm{Cu}\) \(0.0284\) g.

Percentage content of chlorine

Found \(22.53\%\).
Calculated \(22.49\%\).

Percentage content of copper

Found \(20.21\%\).
Calculated \(19.77\%\).

CONCLUSIONS

1. Ternary complexes of hydroquinone- and resorcinol-quinoline with mineral salts have been investigated. Their formulas have been established: with salts of divalent metals—\((\mathrm{C}_9\mathrm{H}_7\mathrm{N})_2 \mathrm{C}_6\mathrm{H}_4(\mathrm{OH})_2 \cdot 2\,\mathrm{MeX}_2\), and of trivalent metals—\((\mathrm{C}_9\mathrm{H}_7\mathrm{N})_2 \mathrm{C}_6\mathrm{H}_4(\mathrm{OH})_2 \cdot 2\,\mathrm{MeX}_3\).

2. Resorcinolquinoline is more difficult to oxidize and is more stable than hydroquinonequinoline; therefore the complexes of the former with mineral salts are also more stable than the corresponding complexes of the latter.

3. Most of the compounds obtained are sparingly soluble in water. The complexes with chlorides of mercury, bismuth, and cadmium are especially difficultly soluble.

4. Hydroquinone- and resorcinol-quinoline, as well as their complexes with mineral salts, are decomposed by water upon boiling, and more readily upon acidification, into their constituent components.

5. The melting points of the complexes with salts of divalent metals are considerably higher than those of the complexes with salts of trivalent metals \((\mathrm{Al}, \mathrm{Fe}, \mathrm{Cr})\).

6. Compounds of hydroquinone- and resorcinol-quinoline with mercury salts possess strongly pronounced antiseptic properties.

LITERATURE

Werner, A.—New Views in the Field of Inorganic Chemistry, 1936.
Hosk, V.—16, 886. 1883.
Wöhler, A.—69, 246. 1849.
Hoffmann,—A. 47, 83. 1843.
Pfeiffer.—Organische Molekülverbindungen.

1. Evidently, a change in composition occurs here. ↩