US1964696A - Complex compound of metals with aliphatic polyhydroxy-carboxylic acids and process of making the same - Google Patents

Description

Patented June 26, 1934 COMPLEX COMPOUND OF METALS WITH ALIPHATIC POLYHYDROXY-CARBOXYLIC ACIDS AND PROCESS OF MAKING THE SAME Wilhelm Traube and Fritz Kuhbier, Berlin, Germany, assignors to Winthrop Chemical Company, Inc., New York, N. Y., a corporation of New York No Drawing. Application December 14, 1931, Serial No. 581,049. In Germany March 21,

32 Claims. (Cl. 260-11) The present invention relates to aprocess of preparing metal complex compounds of aluminium, trivalent iron, trivalent chromium, antimony and bismuth with aliphatic polyhydroxy carboxylic acids and to the basic alkaline-earth metal salts of these complex compounds being intermediate products in the said process.

Metal complex compounds, for instance of aluminium, trivalent iron and antimony have already been prepared.

The present invention provides a process to obtain metal complex compounds of aliphatic polyhydroxy carboxylic acids from their aqueous solutions in a pure, uniform state by Way of the basic alkaline-earth metal salts of the said metal complex compound being insoluble or sparingly soluble in water.

In accordance with the present invention complex compounds of aluminium, trivalent iron, trivalent chromium, antimony and bismuth, which metals have proved equivalent in the process of our present invention, are prepared by first producing basic alkaline-earth metal salts being insoluble or sparingly soluble in water by precipitating these salts by the addition of an alkalineearth metal salt or hydroxide to an aqueous alkaline solution containing an aliphatic polyhydroxy carboxylic acid to which one of the metals above specified is linked in a complex like linkage, said aqueous alkaline solutions being prepared by the action of a salt or hydroxide of the metals specified on an alkaline solution of the aliphatic polyhydroxy carboxylic acid. The basic alkaline-earth metal salts of the metal complex compounds thus obtained in a uniform state are further transformed into their water-soluble alkali-, ammcniumor amine salts by double decomposition with alkali-, ammoniumor amine salts of such acids which yieldwith alkaline-earth metal ions salts insoluble or sparingly soluble in water.

It may be mentioned that the basic alkalineearth metal salts of the metallic complex compounds may further be transformed into the corresponding water-soluble neutral alka1ine-earth metal salts by reacting thereupon with about 1 mol of the complex forming aliphatic polyhydroxy carboxylic acid.

When using in our new process, for instance, an aqueous alkaline solution of ferric-gluconate,

the formation of the basic barium salt proceeds in accordance with the following probable equation:

CsI-I1207+ FeCls +BaC12 5NaOH= Csl-l'zO'zFeBa 5NaCl 5H20.

When transforming the above basic barium salt into the corresponding water-soluble sodium salt the process proceeds probably for instance according to the following equation:

CeHvOvFeBa +NaI-ISO4=CsHsO7FeNa+BaSO4.

The above formula correspond to the result of the analysis.

More graphic formulae would probably be for the basic barium salt the formula:

which may be further explained by the following structural formula:

Fe for the sodium salt-the formula:

Na [O2CeHe (OH) zOsFe] aq.,

which may be further explained by the following structural formula:

CHH.CH.CH.OHOH.OHOH.C O ONa aq.,

Fe for the neutral barium salt the formula:

which may be further explained by the following structural formula:

Ba aq.,

As is to be seen from the above formulae, we presume that the alkaline-earth metal cation substitutes in the insoluble alkaline-earth metal salts, which have been called basic salts, one hydrogen atom of the carboxylic group and another hydrogen atom of a hydroxyl group of the polyhydroxy carboxylic acid; however, in the alkali and alkaline-earth metal salts, which have been called neutral salts, the alkali-, alkalineearth metal cation respectively, substitute only the hydrogen atom of the carboxylic group.

In a similar manner as described above for the production and further transformation of the basic barium ferric-gluconate the process proceeds when using instead of gluconic acid other aliphatic polyhydroxy carboxylic acids and instead of the iron complex compound the corresponding complex compounds of aluminium, trivalent chromium, antimony and bismuth; further instead of a barium salt or barium hydroxide a calciumor strontium salt or hydroxide may be employed. As complex forming polyhydroxy carboxylic acids further may be used, for instance, glyceric-, tartaric-, arabic-, mucic-, saccharic, glucoheptonic-, mannoheptonic, lactobionicacid and the like. As is to be seen from the above formulae in our metal complex compounds about one atom of. aluminium, trivalent iron, trivalent chromium, antimony or bismuth is contained in one molecule of the complex forming hydroxy carboxylic acid and one alkali or alkaline-earth metal atom is bound chiefly by the carboxylic group. This result is in general obtained when reacting upon one mol of the polyhydroxy carboxylic acid with about one mol of a salt or hydroxide of one of the metals specified and adding about one mol of the alkaline-earth metal compound to the solution obtained in order to precipitate the insoluble basic alkaline-earth metal salt. Also in such cases where dicarboxylic acids are employed sometimes no more of the alkaline-earth metal compound is required for the precipitation of the insoluble basic salt. In general, of course, it is advantageous to use a water-soluble alkaline-earth metal salt or hydroxide when precipitating the metal complex compounds as basic alkaline-earth metal salts.

Our new process is advantageously performed by reacting upon an aqueous alkaline solution of the aliphatic polyhydroxy carboxylic acid with about 1 mol of a salt or hydroxide of aluminium, trivalent iron, trivalent chromium, antimony or bismuth and then adding about 1 mol of a salt or hydroxide of an alkaline-earth metal. The basic alkaline-earth metal salt of the metallic complex compound precipitated is separated from the liquid. In order to transform it into a water-soluble product it is decomposedin an aqueous suspension while shaking or stirring with an equivalent quantity of an alkali metal, ammonium or amine salt of an acid which forms water-insoluble salts with alkaline-earth metal ions, for example, with alkali metal ammonium or amine sulfates, bisulfates, carbonates, bicarbonates or oxalates. When the whole quantity of the alkaline-earth metal present in the mixture is transformed into the water-insoluble alkalineearth metal salt, the latter salt is separated from the mixture. From the filtrate the alkali metal, ammonium or amine salt of the metallic complex compound produced may be obtained by evaporating or by precipitating by means of alcohol.

As alkali metal, ammonium or amine salts for the decomposition of the basic alkaline-earth metal salts of the metallic complex compound preferably the salts of the sulfuric, carbonic and oxalic acid, for example, sodium and potassium sulfate, bisulfate, carbonate, bicarbonate, oxalate or bioxalate, or the corresponding salts of ammonia, diethylamine, triethylamine, diethylaminoethanol, ethylenediamine and the like have proved suitable.

The water-insoluble basic alkaline-earth metal salts of the metallic complex compounds may, as already mentioned, further be transformed into water-soluble products by reacting upon the said basic salts with about one equivalent of the aliphatic polyhydroxy carboxylic acid used as complex forming component in the complex compound. The neutral water-soluble alkaline-earth metal salt of the metallic complex compound thus produced may be separated from the solution by evaporating or precipitating by means of alcohol.

The reaction, in general, performs at room temperature, however, sometimes heating is of advantage. Of particular value we consider the production, according to our new process, of the complex compounds of iron, antimony and bismuth, preferably the sodium salts of such ones, as contain a polyhydroxy carboxylic acid derived from hexane as complex forming component, especially gluconic acid.

The products obtainable in accordance with our invention may be used preferably for medicinal purposes, but they may also be employed for the general technical use.

The following examples illustrate our invention without restricting it thereto, the parts being by weight.

Example 1.To a solution of 4.2 parts of ferric-chloride (1 mol) in '70 parts of water 5 parts of gluconic acid and 42.5 parts of a 12% solution of caustic soda possibly free from carbonate (5 mols) are added. The mixture is then treated with a concentrated aqueous solution of 6.2 parts of crystallized barium chloride (1 mol),

whereby a yellow precipitate of barium-ferricgluconate of the formula CsHqovFeBa. aq. separates.

When treating a solution of ferric chloride, gluconic acid and caustic soda prepared in accordance with the above directions with a conif.

centrated aqueous solution of 2.8 parts of calcium chloride (free from water) the basic calciumferric-gluconate of the formula CsHqO7FeCa. aq. is obtained. In order to obtain a very good yield of this salt. it is necessary to heat the solution ii-t;

the calcium salt but in suitably chosen other proportions calcium-ferric-gluconates of another composition, for instance, a salt containing upon 2 molecules of gluconic acid 1 atom of iron and 2 atoms of calcium and having accordingly the formula C12I-lmO14CazFe, and a further salt, containing upon 4 molecules of gluconic acid 3 atoms of iron and 6 atoms of calcium are obtainable.

The described barium and calcium salts may be transformed into water-soluble compounds in the following manner:

Basic barium-ferric-gluconate is made into an even paste with about the same quantity of water.

After cooling to the mixture so much of a concentrated potassium bisulfate solution is added as is required for the transformation of all barium into barium sulfate. When the decomposition is complete the mixture is centrifuged from the barium sulfate. A concentrated solution of the neutral postassium-ferric-gluconate containing upon 1 molecule of the acid 1 atom each of potassium and iron is thus obtained. The salt is separated from the solution by the addition of amine-bisulfate solution).

alcohol. It has the probable formula:

K[O2C6Hs(OH) 2.03F8] aq.,

and accordingly probably the following structural formula:

({3H2.CH.OH.OH.CH.COOK. aq.

O OH H Alternatively, the basic barium-ferric-gluconate may be transformed into a water-soluble compound by making into a paste with some water and decomposing in the same manner as indicated above with the equivalent quantity of ammonium bisulfate. The solution, separated 1 from the barium sulfate formed, is evaporated in vacuo. The ammonium-ferric-gluconate obtained in this manner is readily soluble in water with neutral reaction. It is a yellow powder containing upon 1 molecule of the acid 1 atom of iron and one ammonium group. It has the probable formula: NH4[O2CsHs(OH)2.03FB13CL, and accordingly probably the following structural formula:

CH2.OH.CH.CH.CH.C O ONH4.aq.

O O H OH The neutral dimethylamine-ferric-glueonate is l V obtained when 8 parts of the basic barium-ferric- V barium sulfate from the filtrate, the neutral magnesium-ferric-gluconate readily soluble in water may be isolated by precipitation with alcohol. According to the analysis it is composed according to the formula: (Cel-lsovFelzMg-l-HzO.

The basic barium-ferric gluconate may further be transformed into a water-soluble compond in the following manner:

Into a concentrated aqueous solution containing about -30% of gluconic acid basic bariumferric-gluconate is introduced in small portions until the acid reaction of the liquid has disappeared. The iormed salt at first readily dissolves on stirring. In order to dissolve the rest, gentle heating of the liquid is required. From the finally resulting viscous solution a precipitate of neutral barium-ierric-gluconate separates on the addition of alcohol, which readily changes to a powder on kneading. It contains upon 2 molecules of gluconic acid 1 atom each of iron and barium and corresponds to the probable formula:

Ba [C1zH19O1-1Fe] aq., and probably to the following structural formula;

omoncnon-o H.CH-OH.C oomoo (105111105. aq.

When decomposing this soluble barium salt with calcium sulfate the corresponding calcium-ferricgluconate is obtained according to the following equation:

The basic calcium-ferric-gluconate of the formula: ChzHwOnCazFe, above mentioned is transformed into a soluble compound in the following manner: 2

To a concentrated aqueous solution of 2- molecules of gluconic acid 1 molecule of the basic calcium-ferric-gluconate is added in small portions. It dissolves without leaving a residue when finely ground and gently heated. Alcohol precipitates from the solution thus obtained a light yellow salt, readily soluble in water with neutral reaction, containing upon 4 molecules of gluconic acid 2 atoms of calcium and 1 atom of iron. It has the probable formula Example 2.-1 part of mucic acid is dissolved in parts of a '7-8% aqueous solution of caustic soda and to this solution 2.6 parts of a 67% aqueous ferric chloride solution are added. When adding to the liquid a solution of 0.5 parts of barium chloride in 10 parts of water a white precipitate appears temporarily. The clear solution when heated to boiling, separates a durable whitish precipitate. The mixture is kept boiling for some time and the precipitate is sucked off while hot and washed first with hot water, then with alcohol and ether. The air-dried compound according to the analysis corresponds to the formula When using instead of mucio acid in the above example corresponding quantities of, for instance, saccharic or galaetoni'c acid, the corre- 'sponding complex compounds with similar properties are obtained.

. Example 3.2 parts of gluconic acid,'22 parts of a 12% aqueous solution of caustic soda free from carbonate and 3.1 parts of bismuth chloride are mixed together in order to obtain an alkaline solution containing bismuth This solution is dropped into a heated and continually stirred solution of 2.4 parts of barium chloride in parts of water. The barium-bismuth-gluconate precipitating is separated from the liquid by suction. It is in the dry state a white powder insoluble in water. The yield amounts to 50-60%.

From the above insoluble basic salt a watersoluble product is obtained in the following manner:

Into a concentrated aqueous solution of gluconic acid so much of the difiicultly soluble basic barium-bismuth-gluconate is introduced while gently heating as is dissolved by the solution. The solution obtained, if necessary after filtration, is poured into alcohol, whereby a soluble barium-bismuth gluconate separates, which con tains the double quantity of gluconic acid than the difiicultly soluble salt.

Example 4.-Into a boiling solution of 6 parts of gluc'onic acid in 45 parts of a 13% aqueous caustic soda solution 4.3 parts of antimony trioxide are introduced in small portions. When the antimony trioxide has been dissolved the solution is cooled and mixed with a solution of 7.2 parts of crystallized barium chloride in 25 parts of water. Thereby temporarily a precipitate appears, but afterthe addition of the wholequantity of the barium chloride the solution becomes completely clear.. On heating the solution to boiling the basic barium-antimony-gluconate separates in form of a white crystalline precipitate. It is sucked off while hot, since the pre-' cipitate dissolves again on cooling of the solution. Before separating the precipitate from the liquid, the latter is kept boiling for some time. The precipitate remaining on the filter is washed with hot water, then with alcohol and acetone and dried on an unglazed burned clay plate. According to the analysis the basic barium-antimony-gluconate has the formula:

CsHvOvSbLBa-l- 3H2O.

CizI-ImOrrSbaCzHsNz aq.

separates. It is readily soluble in water.

When using instead of ethylenediamine sulfate sodium sulfate the sodium-antimony-gluconate of the probable formula: CeHsO7SbNa-l-aq. is obtained.

In a similar manner instead of antimony trioxide, antimonic acid may be used for preparing the antimony complex compounds. When, for example, antimonic acid is dissolved in an alkaline solution of gluconic acid and caustic soda and the solution is mixed with a barium chloride solution, a whitish powder separates, which may be isolated in the usual manner.

Example 5.-A concentrated aqueous solution of one part of gluconic acid is mixed with a solution of 1.4 parts of crystallized chromic chloride (containing crystal water) and then, while well shaking, with 8 parts of an about 13% aqueous caustic soda solution; The resulting clear green solution is diluted with some water. Thereto a solution of 1.2 parts of barium chloride in some water is added. Thereby thebasic barium-chromic-gluconate separates in form of a fine-crystalline green precipitate. After heating to boiling the precipitate is sucked off, washed with water, alcohol and acetone and driedon an unglazed'burned clay plate. The compound has the formula:

In order to transform the Water-insoluble basic barium-chromic-gluconate into the water-soluble neutral barium-chromic-gluconate, 2 parts .of the former salt are dissolved in a concentrated aqueous solution of about 0.9-1.0 parts of gluconic acid while gently heating. From the clear solution obtained alcohol precipitates the neutral water-soluble barium-chromic-gluconate of the formula:

Example 6.-To a concentrated aqueous solution of 2 parts of gluconic acid a solution of 2.4 parts of crystallized aluminium chloride and while well shaking a solution of 2' parts of caustic soda in 15 parts of water are added. The clear solution is then mixed with a concentrated aqueous solution of 2.4 parts of crystallized barium chloride. Thereby the basic barium-aluminium-gluconate separates in form of white fine crystals. The precipitate is sucked off, washed with water, alcohol and acetone and dried on an unglazed burned clay plate. The new compound has the formula:

In order to transform the water-insoluble basic barium-aluminium-gluconate into a neutral water-soluble salt, 10 parts of the former salt are made into a paste with 6 parts of water. After cooling to 6 C. the paste is mixed with so much of a concentrated aqueous solution of tetraethylammonium-bisulf ate as is required for the precipitation of the barium in the form of barium sul-' fate. The filtrate from the barium sulfate is evaporated to dryness, whereby the neutral tetraethylammonium-aluminium-gluconate of the formula:

remains. The new compound is hygroscopic and readily soluble in Water and alcohol.

' While we have described our invention in great detail and with respect to preferred embodiments thereof, We do not desire to limit ourselves to such details or embodiments, since many modifications and changes may be made and the invention embodied in widely different forms without departing from the spirit or scope of the invention in its broadest aspects. Hence we desire to cover all modifications and forms within the scope or language of any one or more of the appended claims. 1

We claim:

1. In the process of preparing metal complex compounds the; steps which comprise precipitating from an aqueous solution of an alkali metal salt of. an aliphatic polyhydroxy carboxylic acid to which a metal of the group consisting of aluminium, trivalent iron, trivalent chromium, antimony and bismuth is linked in complex like linkage, said solution containing alkali metal hydroxide, by the addition of an alkaline-earth metal compound selected from the group consisting of the water-soluble salts and the hydroxides thereof the basic alkaline-earth metal salt of the metal complex compound.

2. In the process of preparing metal complex compounds the steps which comprise precipitating from an aqueous solution of an alkali metal salt of a polyhydroxy carboxylic acid derived from hexane to which a metal of the group consisting of aluminium, trivalent iron, trivalent chromium, antimony and bismuth is linked in complex like linkage, said solution containing alkali metal hydroxide, by the addition of an alkaline-earth metal compound selected from the group consisting of the water-soluble salts and the hydroxides thereof the basic alkaline-earth metal salt of the metal complex compound.

3. In the process of preparing complex compounds the steps which comprise precipitating from an aqueous solution of an alkali metal salt one mol of an aliphatic polyhydroxy carboxylic acid to which 1 gram atom of a metal selected from the group consisting of trivalent iron, antimony and bismuth is linked in complex like linkage, said solution containing alkali metal hydroxide by the addition of about 1 mol of a watersoluble alkaline-earth metal compound selected from the group consisting of the water-soluble salts and the hydroxides thereof the basic alkaline-earth metal salt of the metal complex compound.

4. In the process of preparing metal complex compounds the steps which comprise precipitating from an aqueous solution of an alkali metal salt of 1 mol of a polyhydroxy carboxylic acid derived from hexane to which one gram atom of a metal selected from the group consisting of trivalent iron, antimony and bismuth is linked in complex like linkage, said solution containing alkali metal hydroxide, by the addition of about 1 mol of a water-soluble alkaline-earth metal compound selected from the group consisting of the water-soluble salts and the hydroxides thereof the basic alkaline-earth metal salt of the metal complex compound.

5. In the process of preparing metal complex compounds the steps which comprise precipitating from an aqueous solution of an alkali metal salt of 1 mol of a polyhydroxy mono-carboxylic acid derived from hexane to which one gram atom of a metal selected from the group consisting of trivalent iron, trivalent antimony and bismuth is linked in complex like linkage, said solution containing alkali metal hydroxide, by the addition of about 1 mol of a water-soluble calcium salt the basic calcium salt of the metal complex compound.

6. In the process of preparing ferric complex compounds the steps which comprise precipitating from an aqueous solution of an alkali metal salt of one mol of gluconic acid to which one gram atom of trivalent iron is linked in complex like linkage, said solution containing alkali metal hydroxide, by the addition of about 1 mol of a water-soluble calcium salt the basic calcium salt of the ferric complex compound.

7. In the process of preparing antimony complex compounds the steps which comprise precipitating from an aqueous solution of an alkali metal salt of one mol of a polyhydroxy monocarboxylic acid derived from hexane to which one gram atom of trivalent antimony is linked in complex like linkage, said solution containing alkali metal hydroxide, by the addition of about one mol of a water-soluble barium salt the basic barium salt of the antimony complex compound.

8. In the process of preparing antimony complex compounds the steps which comprise precipitating from an aqueous solution of an alkali metal salt of one mol of gluconic acid to which one gram atom of trivalent antimony is linked in complex like linkage, said solution containing alkali metal hydroxide, by the addition of about one mol of a Water-soluble barium salt the basic barium salt of the antimony complex compound.

9. In the process of preparing bismuth complex compounds the steps which comprise precipitating from an aqueous solution of an alkali metal salt of one mole of a polyhydroxy mono-carboxylic acid derived from hexane to which one gram atom of bismuth is linked in complex like linkage, said solution containing alkali metal hydroxide, by the addition of about one mol of a water-soluble barium salt the basic barium salt of the bismuth complex compound.

10. In the process of preparing bismuth complex compounds the steps which comprise precipitating from an aqueous solution of an alkali metal salt of one mol of gluconic acid to which one gram atom of bismuth is linked in complex like linkage, said solution containing alkali metal hydroxide, by the addition of about one mol of a Water-soluble barium salt the basic barium salt of the bismuth complex compound.

11. The process which comprises precipitating from an aqueous solution of an alkali metal salt of an aliphatic polyhydroxy carboxylic acid to which a metal of the group consisting of aluminium, trivalent iron, trivalent chromium, antimony and bismuth is linked in complex like linkage, said solution containing an alkali metal hydroxide, by the addition of an alkaline-earth metal compound selected from the group consisting of the water-soluble salts and the hydroxides thereof the basic alkaline-earth metal salt of the metal complex compound, separating the basic salt, causing it to react in aqueous suspension with at least an equivalent of a salt selected from the group consisting of alkali metal ammonium and amine salts the anion of which salt forms with alkaline-earth metal ions salts difiicultly soluble in water and separating the insoluble precipitate formed.

12. The process which comprises precipitating from an aqueous solution of an alkali metal salt of a polyhydroxy carboxylic acid derived from hexane to which a metal of the group consisting of aluminium, trivalent iron, trivalent chromium, antimony and bismuth is linked in complex like linkage, said solution containing alkali metal hydroxide, by the addition of an alkaline-earth metal compound selected from the group consisting of the water-soluble salts and the hydroxides thereof the basic alkaline-earth metal salt of the metal complex compound, separating the basic salt, causing it to react in aqueous suspension with at least an equivalent of a salt selected from the group consisting of alkali metal, ammonium and amine salts the anion of which salt forms with alkaline-earth metal ions salts difficultly soluble in water and separating the insoluble precipitate formed.

13. The process which comprises precipitating from an aqueous solution of an alkali metal salt of one mol of an aliphatic polyhydroxy carboxylic acid to which one gram atom of a metal selected from the group consisting of trivalent iron and antimony is linked in complex like linkage, said solution containing alkali metal hydroxide, by the addition of about one mol of a water-soluble alkaline-earth metal compound selected from the group consisting of the water-soluble salts and the hydroxides thereof the basic alkaline-earth metal salt of the metal complex compound, separating the basic salt, causing it to react in aqueous suspension with at least an equivalent of a salt selected from the group consisting of alkali metal, ammonium and amine salts'the anion of which salt forms with alkaline-earth metal ions salts difiicultly soluble in water and separating the insoluble precipitate formed.

14. The process which comprises precipitating from an aqueous solution of an alkali metal salt of one mol of a polyhydroxy carboxylic acid derived from hexane to which one gram atom of a metal selected from the group consisting of trivalent iron and antimony is linked in complex like linkage, said solution containing alkai metal hydroxide, by the addition of about one mol of a water-soluble alkaline-earth metal compound selected from the group consisting of the watersoluble salts and the hydroxides thereof the basic alkaline-earth metal salt of the metal complex compound, separating the basic salt, causing it to react in aqueous suspension with at least an equivalent of a salt selected from the group consisting of alkali metal, ammonium and amine salts the anion of which salt forms with alkalineearth metal ions salts dimcultly soluble in water and separating the insoluble precipitate formed.

15. The process which comprises precipitating from an aqueous solution of an alkali metal salt of one mol of a polyhydroxy mono-carboxylic acid derived from hexane to which one gram atom of trivalent iron is linked in complex like linkage, said solution containing alkali metal hydroxide, by the addition of about one mol of a water-soluble calcium salt the basic calcium salt of the ferric complex compound, separating the basic calcium salt, causing it to react in aqueous suspension with at least an equivalent of an alkali metal sulfate and separating the calcium sulfate formed.

16. The process which comprises precipitating from an aqueous solution of an alkali metal saltof one mol of gluconic acid to which one gram atom of trivalent iron is linked in complex like linkage, said solution containing alkali metal hydroxide, by the addition of about one mol of a water-soluble calcium salt the basic calcium salt of the ferric complex compound, separating the basic calcium salt, causing it to react in aqueous suspension with at least an equivalent of an alkali metal sulfate and separating the calcium sulfate formed.

17. The process which comprises precipitating from an aqueous solution of an alkali metal salt of one mol of a polyhydroxy mono-carboxylic acid derived from hexane to which one gram atom of trivalent antimony is linked in complex like linkage, said solution containing alkali metal hydroxide, by the addition of about one mol of a water-soluble barium salt the, basic barium salt of the antimony complex compound, separating the basic barium salt, causing it to react in aqueous suspension with at least an equivalent of an alkali metal sulfate and separating the barium sulfate formed.

18. The process which comprises precipitating from an aqueous solution of an alkali metal salt one mol of gluconic acid to which one gram atom of trivalent antimony is linked in complex like linkage, said solution containing alkali metal hydroxide, by the addition of about one mol of a barium salt the basic barium salt of the antimony complex compound, separating the basic salt, causing it to react in aqueous suspension with at least an equivalent of an alkali metal sulfate and separating the barium sulfate formed.

19. A basic alkaline-earth metal salt of a metal complex compound wherein a metal of the group consisting of aluminium, trivalent iron, trivalent chromium, antimony and bismuth is linked in a complex like manner to an aliphatic polyhydroxy mono-carboxylic acid, said salt being diflicultly soluble in water.

20. A basic alkaline-earth metal salt of a metal complex compound wherein a metal of the group consisting of aluminium, trivalent iron, trivalent chromium, antimony and bismuth is linked in a complex like manner to a polyhydroxy monocarboxylic acid derived from hexane, said salt being difiicultly soluble in water. r

21. A basic alkaline-earth metal salt of a ferric complex compound wherein one atom of trivalent iron is linked in a complex like manner to one molecule of an aliphatic polyhydroxy carboxylic acid, said salt being difiicultly soluble in water.

22. A basic alkaline-earth metal salt of a ferric complex compound wherein one atom of trivalent iron is linked in a complex like manner to one molecule of a polyhydroxy carboxylic acid derived from hexane, said salt being diificultly soluble in water.

23. A basic calcium salt of a ferric complex compound wherein one atom of trivalent iron is linked in a complex like manner to one molecule of a polyhydroxy mono-carboxylic acid derived from hexane, said salt being difiicultly soluble in water.

24. The basic calcium salt of ferric gluconate wherein one atom of trivalent iron is linked in a complex like manner to one molecule of gluconic acid, said salt being diflicultly soluble in water.

25. Basic alkaline-earth metal salts of antimony complex compounds wherein one atom of antimony is linked in a complex like manner to one molecule of an aliphatic polyhydroxy monocarboxylic acid, said salts being difiicultly soluble in water.

26. Basic alkaline-earth metal salts of antimony complex compounds wherein one atom of antimony is linked in a complex like manner to a polyhydroxy carboxylic acid derived from hexane, said salts being difficultly soluble in water.

27. Basic barium salts of antimony complex compounds wherein one atom of trivalent antimony is linked in a complex like manner to one molecule of a polyhydroxy mono-carboxylic acid derived from hexane, said salts being difficultly soluble in water.

28. The basic barium salt of antimony gluconate wherein one atom of trivalent antimony is linked in a complex like manner to one molecule of gluconic acid, said salt being diflicultly soluble in water.

29. Basic alkaline earth metal salts of bismuth complex compounds wherein one atom of bismuth is linked in a complex like manner to one molecule of an aliphatic polyhydroxy carboxylic acid, said salts being difficultly soluble in water.

30. Basic alkaline-earth metal salts of bismuth complex compounds wherein one atom of bismuth is linked in a complex like manner to one molecule of a polyhydroxy carboxylic acid derived from hexane, said salts being diflicultly soluble in water.

31. Basic barium salts of bismuth complex compounds wherein one atom of bismuth is linked in a complex like manner to one molecule of a polyhydroxy mono-carboxylic acid derived from hexane, said salts being difilcultly soluble 5 in water.

32. The basic barium salt of bismuth gluconate wherein one atom of bismuth is linked in a complex like manner to one molecule of gluconic acid, said salt being difiicultly soluble in water. a

W'ILHELM TRAUBE. FRITZ KUHBIER.