NO122102B - - Google Patents

Description

Process for the preparation of water-soluble complex compounds which

contains inorganic phosphate.

The present invention concerns a method for producing a water-soluble complex compound containing inorganic phosphate which is usually water-insoluble. More specifically, the invention concerns a method for producing a substance composition which contains a sugar phosphate salt in complex connection with a usually water-insoluble inorganic phosphate. The term "inorganic phosphate" as used herein means a salt comprising an inorganic ortho-phosphate anion.

It is well known that the inorganic orthophosphates of ammonium, certain low molecular weight organic cations (eg alkyl substituted ammonium) and certain monovalent metal cations (eg alkali metal) are soluble in water, at least to a reasonable extent.

On the other hand, orthophosphates are polyvalent metal cations

(e.g. calcium) either relatively insoluble in water or only incongruently soluble (i.e. the dissolution is followed by a reaction), as e.g. when monocalcium phosphate is dissolved in water, but at the same time exposed to hydrolysis, less soluble dicalcium phosphate is formed. (In general, it has been found that prolonged treatment of any calcium orthophosphate with an excess of water leads to the formation of an insoluble apatite).

It is recognized that the solubility properties are of crucial importance for the possibility of transport and utilization of normally insoluble phosphates in biological systems. In certain plant and animal fluids, calcium phosphate is kept in solution at concentrations that exceed the values that one would expect at the prevailing pH value, and in certain cases these phosphates can be precipitated under special conditions that are important for the formation and maintenance of calcified tissue.

The equilibrium conditions between solid and liquid in the case of polyvalent metal phosphates in aqueous media are exceptionally complicated and are not fully understood.

It is known that many polyvalent metal phosphates (both amorphous and crystalline) can be colloidally dispersed in water to form viscous liquids of poorly defined structure and behavior.

It is also known that phosphates in aqueous media are able to form compounds or complexes with other species (e.g. metallic or organic cations), but many aspects of this phenomenon are still not properly understood.

These properties are the basis for a number of industrial applications of phosphates, but the poor solubility of many orthophosphates is sometimes a disadvantage.

It is an object of the invention to provide complex compounds containing inorganic phosphate which are normally insoluble, but whose properties with regard to water solubility have been improved in order to make them suitable for use in a number of areas, in particular (but not exclusively) by supplying nutrients to animals and plants.

It has been observed that the sugar phosphate salts of a number of polyvalent metallic and organic cations are much more soluble in water than the corresponding inorganic compounds.

This increased solubility is probably due to the hydrophilic character of the sugar group with which the phosphate groups are connected. Generally speaking, the water solubility of the salt is greater the greater the ratio between hydroxyl and phosphate on the sugar molecule. For example the calcium salts of sucrose monophosphates are exceptionally soluble in water, the limit of their solubility apparently being determined only by the very large increase in viscosity at high concentrations (i.e. solutions containing more than approx.

250 g of salt per 100 g of water). The calcium salts of glucose monophosphates are also easily soluble in water, although to a lesser extent than the salts of sucrose monophosphates. The calcium salts of hexosediphosphates, e.g. fructose-1:6-diphosphate, however, are considerably less soluble. It has been found that the same consideration is valid for the other polyvalent metal salts of sugar phosphates. When the multivalent metal is e.g. copper, iron, aluminium, tin, lead or zinc, the sugar phosphate salt is thus always more soluble than the corresponding inorganic compound. It is e.g. possible to dissolve as much as 160 g of aluminum sucrose phosphate in 100 g of water at 20°C, while inorganic aluminum phosphate is insoluble in water under the same conditions.

It has also been observed that sugar phosphates in aqueous media are stable

to form compounds or complexes with polyvalent metallic and organic cations in a similar manner to inorganic phosphates.

The above-mentioned properties of sugar phosphates suggest a possible

large application in areas similar to those where inorganic phosphates are currently used extensively.

It is a further purpose of the invention to improve the applicability of sugar phosphates in a number of areas of application corresponding to those where inorganic phosphates can be used.

The complex compounds or substance compositions produced according to the invention are a synergistic combination of one or more sugar phosphate salts and one or more usually water-insoluble, inorganic phosphates, the combination having properties that are markedly different from the properties of the individual components.

These compositions can, among other things, be formed by a sugar being phosphorylated in the presence of a suitable base of a polyvalent metal ion, after which a product containing sugar phosphate salts in complex with the inorganic phosphate of the polyvalent metal ion is recovered from the reaction mixture. For example, a product containing calcium sucrose phosphates in complex with inorganic calcium phosphate can be recovered from the reaction mixture obtained by phosphorylating an aqueous solution of sucrose and lime.

It has been found that compositions which are soluble in water can be prepared in this way to form solutions which contain a significant amount of soluble inorganic phosphate (which is usually water insoluble) and which are stable for a long time at concentrations above about 5% by weight of the total dissolved phosphates.

A dilution of these solutions is found to give a slow precipitation of an insoluble phosphate associated with some sugar phosphate. The precipitated material is highly dispersed and essentially amorphous and, depending on the concentration conditions, can form a gel or a tough cloudy solution. When the solution is concentrated again, the precipitated substance dissolves again.

When calcium sucrose phosphates which are substantially free of inorganic calcium phosphates are thoroughly mixed during comminution with an inorganic calcium phosphate, the resulting product exhibits solubility properties in water which are not significantly different from the known properties of the two components. The calcium sucrose phosphate component is dissolved, and the inorganic calcium phosphate will either remain undissolved or dissolve incongruously. (As mentioned earlier, the most basic inorganic phosphates will remain largely undissolved, while the less basic inorganic phosphates initially dissolve, but later cause precipitation of a less soluble, more basic phosphate).

The component of inorganic calcium phosphate can of course be dissolved

by acidifying the aqueous mixture. Provided that the concentration of calcium sucrose phosphate in solution is sufficiently high, however, it has been found that careful neutralization of the mixture will not result in precipitation of inorganic calcium phosphate. This is also the case for solutions that have been brought up to pH values above 7. Such a result is unexpected, as it is known that inorganic calcium phosphates precipitate in neutral and alkaline solutions when sucrose phosphates are not present. It has been found that these neutralized solutions are stable for long periods of time at concentrations of calcium sucrose phosphates exceeding approx. 5%.

A dilution of the solution has been found to cause a slow precipitation of calcium phosphate associated with some calcium sucrose phosphate. The precipitated material is highly dispersed and essentially amorphous and, depending on the concentration conditions, can form a gel or a viscous cloudy solution. When the solution is concentrated again, the precipitated substance is dissolved again.

In the same way as the reaction mixture formed by phosphorylating an aqueous solution of sucrose and lime, the neutralized solution described above also comprises inorganic calcium phosphate in complex association with calcium sucrose phosphates. It has already been mentioned that such a composition cannot be prepared by finely dividing the two components, then mixing them with water, and it is also important to note that it cannot be prepared by certain double decomposition reactions in solution.

Precipitation of polyvalent metal phosphates cannot therefore be avoided

(in basic solution) by dissolving a sugar phosphate salt in water and simultaneously adding dropwise with vigorous stirring separate aqueous solutions containing respectively a) a soluble inorganic phosphate salt and b) a soluble inorganic non-phosphate salt of the multivalent metal ion.

Nor can the precipitation of polyvalent metal phosphate (in alkaline solution) be avoided when dissolving the sugar phosphate salt by a cation whose inorganic phosphate is usually soluble in water (e.g. sodium, potassium, ammonium) together with the corresponding soluble inorganic phosphate salt and addition under vigorous stirring of an aqueous solution containing the component mentioned above under b).

It will be clear from these examples that soluble compounds between sugar phosphate salts and usually insoluble inorganic phosphates can only be produced by specific methods, and that these methods are not obvious from the knowledge of the individual properties of the constituents. Preferred methods for producing the compounds will be described in detail later.

The invention relates to a method for producing a complex compound in solid form or aqueous solution consisting of two components a and b, the component a being at least one salt of a sugar phosphate and the component b being at least one inorganic phosphate of a polyvalent metal cation which is usually will form a mainly insoluble phosphate, and which is chosen ui * i +• ^ 2+ r 2+ IV* 2+ - 7 2+ M-2+ c 2+ ir<2>+xr 3+ ~<Al3+> the cations Ca , Cu , Mn , Zn , Ni , Sn , Fe , Fe and Al , while the aforementioned compound is such that when the total sugar phosphate and inorganic phosphate dissolved in water exceeds 5 parts by weight per 100 parts by weight of water, there is at least 2% by weight of component b calculated on the weight of component a in solution at ambient conditions, characterized in that a solution of components a and b is prepared with a pH value that is not significantly lower than 7, and that the above-mentioned complex compound which is thereby formed, is extracted from the solution, e.g. by using a precipitation with alcohol, the special case where the reaction mixture is prepared by phosphorylating one or more sugars in the presence of a calcium oxide compound in a stoichiometric ratio is excluded. The reason for the aforementioned exception is that this special phosphorylation method is the subject of Norwegian patent no. 109,332.

Generally, no specific upper limit can be given for the proportion by weight of component b which is soluble in water under the conditions stated above, but usually the proportion of dissolved component b will not exceed 25% by weight calculated on the weight of the dissolved component a.

In the above definition of the complex compounds or substance compositions that can be produced by the method according to the invention, the solubility of the component of inorganic phosphate is put in connection with the case that the total content of dissolved phosphate exceeds approx. 5 parts by weight per 100 parts by weight of water. It will be understood that only some of the complex compounds are such that at least 2 percent by weight of component b calculated on the weight of component a is soluble in water under ambient conditions when the total content of dissolved phosphate in the solution does not exceed approx. 5 parts by weight per 100 parts by weight of water. However, all the complex compounds satisfy the definition given above.

As an explanation for this apparent irregularity, it must it is emphasized that the nature of the complex compounds is such that the component of inorganic phosphate is more soluble in water at higher concentrations of sugar phosphates than at lower concentrations.

It has previously been mentioned that inorganic phosphates, which are usually insoluble in water, can largely be dissolved by acidifying their aqueous dispersions, and the invention comprises that the aforementioned solution of components a and b is prepared by an acidified aqueous solution of a such inorganic phosphate, and furthermore comprising a sugar rf phosphate anion, is neutralized by the addition of a base. It will be understood that the polyvalent metal cation (e.g. calcium) in this method can be obtained either from the added base or from the acidified solution. The substance composition that has been produced in this way has included those where the sugar phosphate is sucrose phosphate or glucose phosphate. In many applications, acidic conditions cannot be tolerated, and it is an important advantage of the material compositions produced according to the invention that they are not only soluble under acidic conditions, but also under neutral and alkaline conditions.

Although sugar phosphates constitute a rapidly expanding branch of chemistry (especially as regards their application in the biological field), few if any sugar phosphates have been produced in quantities for any significant industrial utilization.

When polyhydroxy compounds such as sugars are phosphorylated, any one or a number of the hydroxyl groups can be esterified. Selective esterification is only possible when special methods are used (e.g. when enzymatic reactions are used or substituted phosphoryl chlorides are reacted with sugar molecules that carry protective hydroxyl groups in suitable positions). Processes for the preparation of certain simple sugar phosphates are therefore likely to remain prohibitively expensive for widespread industrial application.

According to the invention, however, a method has been developed for the production of compositions which satisfy the above-mentioned solubility criteria, and this method comprises the phosphorylation of a sugar in the presence of a suitable base of a polyvalent metal ion under conditions which allow the recovery of a product consisting mainly of a mixture of sugar phosphate salts of the metal ion in complex with the inorganic metal ion phosphate.

Although the following examples show the use of mixtures

of sucrose or glucose phosphates, it will of course be understood that the substance compositions or complex compounds produced according to the invention also include simple sucrose or glucose phosphates.

Likewise, the substance compositions that can be produced according to the invention can include sugar phosphates other than sucrose or glucose phosphates (e.g. fructose, maltose or lactose). Preparations of mixtures of phosphates of different sugars are also covered by the invention.

The proportion of inorganic phosphate in the product can be controlled by such factors as the concentration and rate of addition of the reaction components, the reaction temperature, the degree of agitation and the method of extracting the product. When phosphorylating sucrose in aqueous solution in the presence of lime with phosphorus oxychloride in solution in trichloretine, the proportion of inorganic calcium phosphate in the product can e.g. can be varied by suitable regulation of variables.

Factors that lead to an increase in the proportion of inorganic phosphate in the product are:

1. Increasing the reaction temperature between 0 and 25°C,

2. reduction of the degree of agitation during the reaction,

3. increase in the concentration of phosphorus oxychloride in the trichloretine,

4. increased rate of addition of phosphorus oxychloride in the trichloroethene

during the reaction.

With the same production method, the proportion of inorganic phosphate in the product can also be changed by changing the method for extracting the product from the reaction mixture. This is shown in the following examples

on the preparation of compositions A and D. These examples and that relating to the preparation of composition E illustrate methods which are related to methods which fall within the scope of the invention. Composition F is produced by a method that lies within the scope of the invention, while compositions B and C are produced by methods that fall outside the scope of the invention, and which are not even related to methods that lie within the scope of the invention.

Composition A:

A solution of 127 kg of sucrose in 63.5 L of water was mixed with 295 L of water and 68 kg (the stoichiometric amount) of slaked lime in a reaction vessel. Additional water was added to adjust the volume to 591 L. The solution was cooled to 5°C and held at this temperature for 8 hours, during which time 54.5 kg of phosphorus oxychloride dissolved in 54.5 kg was added gradually and with vigorous stirring. . the trichloroethene. When the reaction was complete, the mixture was centrifuged to remove suspended solids and the trichloroethene and then pumped into a glass-lined vessel where 2000 L of denatured absolute alcohol was added with stirring to precipitate the product. The precipitated product was separated and leached in four separate amounts of 80% ethanol, before being collected in a centrifuge and dried to a fine white powder.

The product is a complex compound of calcium sucrose phosphates with inorganic calcium phosphate together with small constituents characteristic of the reaction (e.g. traces of calcium chloride).

This substance composition is easily soluble in water, and stable viscous solutions containing as much as 70% dissolved solids can be produced there. The solutions contain approx. 19 percent by weight of dissolved inorganic calcium phosphate (calculated on the weight of the calcium sucrose phosphates present) and has pH values above 7 (a 5% solution calculated on the total amount of dissolved phosphates has, for example, a pH value of 9.2) .

If these solutions are diluted with water to less than approx. 10 parts by weight total dissolved phosphates per 100 parts by weight of water, they will slowly begin to precipitate insoluble matter consisting of calcium phosphate associated with some sucrose phosphates. Both the form and composition of the precipitated material, the amount precipitated and the rate of precipitation depend, among other things, on the concentration of the solution. When the solution is allowed to stand for a number of days at concentrations of approx. 5 parts by weight total dissolved phosphates per 100 parts by weight of water, it has been found that less than approx. 2% of the inorganic phosphate (calculated on the weight of sucrose phosphate present) remains in solution.

It will appear later that a variation in the solubility of the inorganic phosphates and the slow precipitation of these substances upon dilution are properties which are of fundamental importance for many applications of the compositions to which the invention relates.

An analysis of a particular batch of the above-mentioned composition by conventional methods (which have been tested for reliability) gave the following result (expressed as a percentage of the dry weight of the composition):

An important method that has been used to help identify the compounds is zone electrophoresis (paper). This method can be performed with a variety of buffers, pH values, concentrations and voltage gradients. The relative mobility of the various components depends on these parameters, but the following conditions have been found to be applicable: Buffer: 5% pyridine, 0.5% glacial acetic acid in water (pH value 6.0), paper: Whatman no. 54,

voltage gradient: 16 Volt/cm,

separation time: 2-2.5 hours.

Localization of the constituents on the paper after drying can conveniently be carried out by the application of an ammonium molybdate reagent which gives a blue color in the presence of phosphate.

A typical electrophoresis pattern is shown in fig. 1. This figure compares the results for four different products that were subjected to electrophoresis in the same quantities. The composition denoted by A was prepared by the special phosphorylation method described above, while the compositions B, C and D were prepared by methods that will be described later.

Compositions A and D, which are prepared by processes related to processes within the scope of

invention, contains more than 2% by weight of soluble inorganic phosphate calculated on the weight of the associated sucrose phosphates, while compositions B and C, which are produced by methods outside the scope of the invention, contain less than this amount of soluble inorganic phosphate.

Band analysis. Composition A:

Composition A is seen to be characterized by five bands. Of these, the fastest band (no. 5) corresponds to inorganic phosphate and the remaining bands (no. 1-4) to sucrose phosphates with different molecular structures.

The methods used to characterize these different bands have included conventional analysis, infrared spectrophotometry, neutron activation analysis, determination of formula weights and X-ray diffraction to determine the nature of the inorganic phosphates that are formed

when the substances are roasted at 800° C.

These methods have shown that composition A consists of approx. 15%

(by dry weight) of an inorganic calcium phosphate which in the solid state exists mainly as an amorphous tricalcium orthophosphate in connection with approx. 80% (by dry weight) of a mixture of amorphous calcium salts of a variety of sucrose phosphates. The remaining dry material consists of some calcium chloride and traces of free sucrose.

A general confirmation of. that the electrophoresis bands 1-4 consist of components of sucrose phosphate can be obtained by elution of these bands followed by controlled hydrolysis in aqueous solution (using acids, alkali or enzymes) to give free inorganic phosphates and the free sugars or their hydrolysis products.

The detailed determinations carried out on the sucrose phosphate component suggest that the four bands 1 - 4 in the particular composition A consist of the following types of sucrose phosphate. It will of course be understood that the decisive properties of substance composition are in no way invalidated by theoretical errors in the assignment between the sucrose phosphates and the various bands. In the analysis, an attempt has only been made to elucidate the nature and the complicated nature of the sugar phosphate constituents which can be used in compositions prepared according to the invention.

There is evidence to suggest that band 1, which is derived from less than 5% of the total dry weight of the composition, consists of di-sucrose phosphate anions of the type

where R is the sucrose molecule minus a hydroxyl group.

There are signs that band 2, which is derived from ca. 55% of the composition's total dry weight consists of sucrose monophosphate anions of the type

where R is the sucrose molecule minus a hydroxyl group.

There are signs that band 3, which is derived from ca. 10% of the composition's total dry weight consists of cyclic sucrose monophosphate anions of the type

where R' is the sucrose molecule minus two hydroxyl groups.

There are signs that band 4, which is derived from ca. 15% of the composition's total dry weight consists of sucrose diphosphate anions of the type

where R' is the sucrose molecule minus two hydroxyl groups.

It will be understood that these bands do not necessarily relate to simple, pure compounds, as in certain cases they may consist of isomeric sucrose phosphates. The complex nature of these sucrose phosphates has prevented a complete identification of the molecular structure of each component.

The properties of the synergic phosphate combination the invention relates to must vary to a certain extent with the variations in the particular identity of the sugar phosphate components, but these variations will fall within the limits of the stated solubility of the substance composition.

Composition B:

This composition was prepared according to the method which

is described in German patent document No. 247,809, and it essentially consists of a mixture of sucrose phosphates of a similar nature to those attributed to composition A, but in different proportions.

In accordance with this procedure, a solution of phosphorus oxychloride (77 g; 0.5 mol) in alcohol-free chloroform (250 ml) was slowly added to an ice-cold solution of sucrose (180 g; 0.53 mol) in water (2000 ml) in which had been leached and suspended a stoichiometric excess of calcium oxide (115 g; 2.05 mol). After stirring for several hours, the solution was filtered and carbon dioxide was introduced into the filtrate to remove excess calcium oxide as carbonate. The filtered solution was then concentrated and alcohol was added to precipitate a calcium sucrose phosphate composition containing calcium chloride. To obtain a composition free of calcium chloride, the precipitated material was dissolved in water and precipitated with alcohol five or six times.

Analysis of a particular batch of the composition by conventional methods gave the following result (expressed as a % of the dry weight of the composition):

Composition B only contains approx. 0.25% (by dry weight) of

an inorganic calcium phosphate and is easily soluble in water, as a solution is obtained which is stable at practically all concentrations. For this reason, composition B does not exhibit the properties to which the compositions of the invention relate, and thus has small advantages in relation to sugar phosphates as such.

Composition C:

This composition was prepared from composition A in the following manner. A 2% aqueous solution of A was allowed to stand for several days, whereby a colloidal precipitate was formed which was recovered by centrifugation. Ethanol was added to the resulting supernatant and compound C was precipitated.

Analysis of a specific batch of the composition by conventional methods gave the following result (expressed as a % of the dry weight of the composition):

As will appear from this analysis and from fig. 1 (and which can be confirmed by other methods mentioned earlier), this material is essentially similar to composition B, but contains approx. 1% of an inorganic calcium phosphate.

In the same way as composition B, composition C is easily soluble in water and gives a solution which is stable at almost all concentrations. This entails only a small advantage compared to sugar phosphates as such.

Composition D:

This composition was prepared by a modification of the phosphorylation process described for composition A. Instead of the reaction product being precipitated after the reaction mixture had been centrifuged, an amount of disodium hydrogen phosphate corresponding to the free chloride that was left in the reaction mixture was added. The resulting solution was then evaporated to dryness.

Analysis of a specific batch of the composition by conventional methods gave the following result (expressed as a % of the dry weight of the composition):

Using previously mentioned methods, it has been shown that composition D consists mainly of the following components in approximately the following proportions: 35% calcium sucrose phosphates, 29% tricalcium phosphate, 17% free sucrose and

19% sodium chloride.

An analysis of the electrophoresis bands 1-5 for composition D gives similar results to the electrophoresis bands 1-5 for composition A. The faint band below band 1 for composition D in FIG. 1 corresponds to free sucrose.

About 57% of this composition is soluble in water at a weight ratio of 1:5 between total solids and water. The two phases have the following approximate compositions:

The calculated weight of soluble calcium sucrose phosphates is thus approx. 8% tricalcium phosphate soluble in water at a concentration of approx. 4 percent by weight

• total soluble inorganic phosphates and sucrose phosphates.

This composition contains a significant amount of soluble inorganic phosphate in complex connection with a mixture of sucrose phosphates and exhibits the advantageous properties which are characteristic of the substance compositions to which the invention relates.

As an example of the invention, a description of the preparation of and the properties of a composition consisting of calcium glucose phosphates in connection with inorganic calcium phosphate will be given.

Composition E:

90 g of glucose was dissolved in 1.5 L of water, and 92.5 g of calcium hydroxide was added to the solution. The mixture was then cooled to 0° C. and kept at this temperature while 46 ml of phosphorus oxychloride dissolved in 75 ml of trichloroethene was added gradually and with vigorous stirring. The reaction mixture was then stirred for 1 hour before being centrifuged to remove any undissolved material. The resulting mixture was then concentrated to about 40% solids, and the reaction product was precipitated by addition of ethanol to a concentration of approx. 90 percent by weight calculated on the weight of the liquid. The product was isolated and dissolved and reprecipitated four times under similar conditions to remove soluble impurities (eg calcium chloride).

The dried product is a composition that lies within the framework of the compositions to which the invention relates, and which has the following elemental analysis (expressed in % of dry weight):

That the composition is a compound of inorganic calcium phosphate with calcium glucose phosphates can be shown, among other things, by zone electrophoresis.

In fig. 2 shows a diagram comparing the pattern obtained when equal amounts of composition E and the previously described composition A were subjected to electrophoresis under conditions corresponding to those already described. The patterns are different, but both show the same fastest band of inorganic phosphate which for composition A is designated as band 5 and for composition E is designated as band 4'.

In the case of composition E, by applying the methods mentioned earlier in connection with sucrose phosphates, it can be shown that the remaining bands correspond to glucose phosphate components. There are indications that the main group of glucose phosphates present in the composition (and which corresponds to band 2') consists of glucose monophosphates.

It can also be shown that composition E mainly consists of a mixture of essentially amorphous calcium salts of the described glucose phosphates (approx. 90% of the composition calculated by dry weight) in complex connection with an inorganic calcium phosphate which exists in solid form as a mainly amorphous tricalcium phosphate (approx. 7% of the composition calculated by dry weight).

Composition E is completely soluble in water provided the resulting solution is sufficiently concentrated (eg 50% solids by weight). The solution has a pH value of approx. 7 and contains approx. 8% inorganic calcium phosphate calculated on the weight of calcium glucose phosphates present. When the solution is diluted to approx. 1 part by weight of total dissolved phosphates per 100 parts by weight of water, it is quickly blurred as a result of precipitation of finely divided insoluble material.

Composition F:

•This compound was prepared by phosphorylation of sucrose i according to the method described above according to German patent document no. 247,809 (stoichiometric excess of lime) and subsequent recovery of a complex compound of calcium sucrose phosphate and inorganic calcium phosphate from the reaction mixture.

A solution of 90 g of sucrose in 1 liter of water was prepared, and 57.5 g of calcium oxide was mixed with the solution, which was then cooled to approx. 0° C and held at this temperature for one hour. During this time, 38.5 g of phosphorus oxychloride dissolved in 0.125 1 of trichloroethene was gradually added with vigorous stirring. The mixture was then filtered to remove unreacted calcium hydroxide, and the filtrate was neutralized by the addition of a suitable acid (85% phosphoric acid).

The reaction mixture was then poured into 5 L of absolute ethanol, and the precipitated substance was further purified by extraction three times in portions of 0.4 L of 80% ethanol in water. The thus produced product contained little remaining calcium chloride and was dried in a vacuum at 60°C.

Analysis of a specific batch of the composition by conventional methods gave the following result (expressed as a % of the dry weight of the composition):

By means of previously mentioned methods, it has been shown that composition F mainly consists of the following components in percentage by weight: 60% calcium sucrose phosphates and 40% inorganic calcium phosphate. With the zone electrophoresis method described above, it has been shown that five electrophoresis bands are obtained for composition F, and that an analysis of these gives similar results as for electrophoresis bands 1-5 for composition A.

The compositions described above have all concerned that case

that the cation in the inorganic phosphate component is calcium. General methods (e.g., phosphorylation of sugars in the presence of a suitable base) for the preparation of compositions in which the cation of the inorganic phosphate is any other suitable polyvalent metal have already been disclosed, and it has been determined that these methods are applicable in the case of a number of such other cations, e.g. Cu^, Ni^<*>. The cation in any given composition may also be replaced by any polyvalent metal cation to give other compositions falling within the scope of the invention.

The replacement can be carried out by a number of methods, three of which will be described below. The correct procedure must be chosen taking into account the properties of the respective compositions. It will be understood that the stated methods are only examples and do not indicate any limitations.

In the description of the methods, "desired polyvalent metal" means the metal which is to replace the metal in a composition to give another composition which lies within the scope of the invention.

Procedure 1.

A solution of composition A is passed through a column which

is filled with a cation exchange resin (e.g. Dowex 50-X2) in acid form.

This treatment removes most of the calcium ions from the composition without significantly changing the proportions of inorganic phosphate and sucrose phosphates in the solution flowing out of the column. The solution is then reacted with such a slight excess of the recently precipitated hydroxide of the desired multivalent metal (e.g. nickel) that a final pH value of between 7 and 8 is obtained. Excess hydroxide is filtered off, and the filtrate is evaporated to the is dry to give the composition.

Procedure 2.

A similar cation exchange resin in acid form is converted in a column to the form corresponding to the desired polyvalent metal, by passing a 10% solution of a soluble salt of the metal through the resin. After the resin has been washed clean of unwanted anions, a solution of a substance composition prepared by the method according to the invention is passed through the column, whereby an exchange of metal ions takes place. The solution flowing from the column can be evaporated to dryness, or the composition can be recovered by precipitation with alcohol.

Procedure 3.

To a 10% solution of the substance composition is added a 5% solution of a soluble salt whose cation consists of the desired multivalent metal, and whose anion is able to form an insoluble salt with the metal in the original composition. The precipitate that forms is filtered off and the filtrate is evaporated to dryness to give a composition containing the desired polyvalent metal. If there e.g. is to produce a composition containing soluble stannous phosphate, a solution of stannous fluoride is added to a solution of a calcium-containing substance - composition, so that insoluble calcium fluoride is precipitated. This is filtered off, and the filtrate is evaporated to dryness to give the desired composition.

From these examples, it will be clear to those skilled in the art that a number of different compositions can be prepared from other compositions according to the invention by replacing the polyvalent metal ions or organic cations with other such ions. Examples of some of the compositions prepared include compositions containing copper (Cu^), manganese (Mn^), zinc (Zn^), tin (Sn^<*>), aluminum (Al^^), nickel ( Ni^<*>) and iron (Fe^ and Fe^). All these compositions exhibit the properties which are characteristic of the compositions to which the present invention relates.

Composition G:

This composition contains soluble copper phosphate and was prepared from composition A by method 2. The composition has the following elemental analysis (expressed as % of dry weight):

This composition essentially consists of approx. 14% (calculated on the basis of dry matter) copper phosphate in connection with approx. 80% copper sucrose phosphate. The composition is soluble in water and forms a clear green solution at a pH value of 8, and the rate of dissolution is greatly increased by heating. When diluted to form a solution-with approx. 1% total soluble solids, the solution becomes cloudy due to precipitation of a well-dispersed insoluble material consisting of inorganic copper phosphate associated with copper sucrose phosphates.

Ionized compounds in aqueous solution can lie anywhere on a scale between relatively simple complex formation and more complicated ion interactions that take place in complex coacervation and floc formation. The latter interaction phenomena are largely dependent on factors such as e.g. The pH value, the concentration of the interacting components (both absolute and relative), the ionic strength and the nature (specificity) of the interaction.

The physico-chemical basis for the dissolution properties of the compositions to be produced according to the invention obviously includes a complex interaction or interaction of ionized components. However, the exact mechanism of these interactions is so far only poorly understood, and this applies not only to the mentioned systems, but also to most other systems.

Studies of sugar phosphates have shown that these substances can form complex compounds with polyvalent metal ions and are absorbed at the interface between solid and liquid, particularly on solid inorganic phosphates. It has been found that adsorption of sugar phosphates on solid inorganic phosphates can lead to a marked dispersion of these solids (which points to the fact that sugar phosphates can be used as a means of dissolving flocs (deflocculating agents) in a number of cases). It has also been observed that sugar phosphates can interact with large organic cations at suitable pH values and concentrations to form insoluble products.

Inorganic phosphates can also behave in a similar way. Thus, when inorganic phosphates and sugar phosphates are brought together in aqueous solution, complex interaction phenomena can occur which affect the solubility properties in the manner already described for the compositions to which the invention relates. As a result of these interactions, the properties of these soluble compositions of sugar phosphates and inorganic phosphates will in many cases be different from the properties of the individual components. It has already been pointed out that dis-

se compositions can only be produced by certain selected methods, and it is believed that this is due to the complexity of the relevant interactions and differences in the dynamics of the reactions in opposite directions for the various equilibrium states (the kinetics of the forward and reverse reactions for the various equilibria).

The connection between sugar phosphates and inorganic phosphates that exists in the compositions to which the invention relates gives these products advantages in many applications, not only in relation to the use of inorganic phosphates, but also in relation to the use of sugar phosphates.

This is evident from the following example.

It is generally agreed that the dissolution of hydroxyapatite

(a calcium phosphate that makes up the majority of tooth enamel) is probably an early stage in the formation of caries damage to teeth. In attempts to reduce the occurrence of dental caries in humans, attention has been directed towards a delay in the demineralisation of the tooth enamel by the addition of phosphates to foodstuffs. The problem of rehardening teeth whose enamel has softened as a result of demineralization has also been studied. In both of these ways of combating dental caries, calcium phosphates stand out as the phosphates that are most likely to be able to delay the demineralization of the tooth enamel in a natural way or at least partially bring minerals that have been lost from the tooth enamel back to it. However, as mentioned earlier, calcium phosphates are either poorly soluble in water at physiological pH values or they form insoluble phosphates under these conditions.

The calcium compositions which the present invention an-

goes, however, provides calcium phosphates in a soluble form, not only as calcium sugar phosphates, but as soluble inorganic phosphates in complex connection with these sugar phosphates. It has been shown that these compositions are effective when it comes to preventing the demineralization of tooth enamel in vitro and the occurrence of caries damage both in animals and

human beings. Some examples are given below.

When a human tooth whose enamel has previously been softened in a buffer solution is introduced into a diluted solution of the below-mentioned toothpaste containing composition A, the enamel will become hard again, which can be measured by the usual Knoop method of hardness measurement.

Dilute to a total of 100 parts by weight.

This toothpaste is produced by standard methods. The indicated composition A corresponds to that described earlier in the preparation, i.e. it consists of special calcium sucrose phosphates in complex connection with inorganic calcium phosphate.

This toothpaste has been compared with a control toothpaste which does not contain compound A, in extended tests with school children. The proportion of attacked, missing (missing) or sealed tooth surfaces

was found to be less for children who used the toothpaste containing composition A than for children who used the control toothpaste. The differences between the sample group and the control group were significant at the 0.1% level.

It has also been demonstrated that the addition of compositions based on a compound between calcium sucrose phosphates and inorganic phosphate to the diet of rats that are prone to caries, reduces the frequency of caries in these animals compared to control groups fed with similar amounts of inorganic phosphates. As it is recognized that results from the fight against dental caries in animals are also valid for humans, and on the basis of the proven effect on humans of the mentioned compounds in toothpastes, it is reasonable to conclude that the addition of these compositions to foods will also reduce the incidence of dental caries in humans.

The composition according to the invention has a wide range of applications

in connection with animal and plant nutrition. Dissolved as aqueous solutions

provides the compounds phosphate and important metal ions in a form that is very similar to the form in which these components occur in liquids in biological systems.

It is well known in connection with the nutrition of both animals and plants

that even if the nutrients contain significant amounts of phosphates and important metal ions, these will not always be immediately available so that they can be utilized by the growing organism. The form in which the nutrients are available is of significant importance for their availability. Milk is e.g. "a good example that calcium and phosphates, which are important for rapidly growing young animals, are present in an easily assimilable form. The connection between calcium and phosphates in milk is exceptionally complex, and the solubility properties of calcium phosphate are typical of the complex relationship that exists in many biological fluids.

The presence of phosphates in plant seeds and fruit is also very complicated. In such tissues, inorganic phosphates are generally associated with organic phosphates, and both of these phosphate types are present in a form that is easily accessible to the germinating plant.

Obviously, insoluble inorganic calcium phosphates will not

be as easily accessible to adult organisms as those that are soluble or highly dispersed, as they are in biological fluids. Alkali metal or ammonium salts of inorganic phosphates are relatively easily soluble in water, but they often have to be used in animal or plant nutrition in connection with polyvalent metal ions with which they tend to form insoluble salts. The advantages of the compositions to which the invention relates are due to the fact that they can provide phosphates in the presence of polyvalent metal ions, while both of these components are soluble. When the phosphates contained in these compositions are precipitated under certain conditions, they will further be precipitated in a highly dispersed state, which is advantageous in the above-mentioned and other applications.

The applicability of the indicated compositions as improved sources of calcium and phosphate for growing organisms will be apparent from the following example.

Groups of soybeans previously conditioned to contain 13% moisture, and which had been stored in cans at room temperature for 6 months, were dipped for 10 minutes in respectively 1) a 0.5% solution of composition A, which is the previously described composition,

2) a 0.5% solution of monopotassium phosphate,

3) a 0.5% solution of sucrose,

4) a 0.5% solution of sucrose plus lime, containing calcium in an amount corresponding to the content of solution 1.

When using solution 1, the viability of the seeds was significantly increased, improving on average by approx. 20% compared to a control group. When using solution 2, there was less effect,

and with solutions 3 and 4 no increase in viability could be demonstrated.

It was found that a treatment with solution 1, in addition to increasing viability, also gave a marked increase in root growth. Compared to a control group, the improvement in this respect was 50% (calculated on the dry weight of the root shoots) for solution 1. The improvement when treated with solution 2 was smaller (10% compared to the control group), and solutions 3 and 4 showed no significant increase in root growth.

From the foregoing it will be clear that it is possible with advantage

to use the compositions to which the invention relates to supply plants and animals with soluble easily assimilable phosphates, important metals and trace metals (e.g. calcium, magnesium, copper, iron, zinc).

The applications in the biological area are discussed with particular reference to compositions that comprise a compound between sucrose phosphates and inorganic phosphate, but it will be understood that biologically applicable compositions that fall within the scope of the invention also include other sugar phosphates (e.g. glucose phosphates ) in connection with inorganic phosphate.

A further application of the described compositions is based on the improved interaction of these compounds in aqueous solution with organic cations.

It is known that both inorganic phosphates and organic phosphates can under certain conditions form insoluble interaction products with large organic cations. These conditions have led to the use of phosphates as a precipitating agent for water-soluble proteins under conditions where the proteins are positively charged, and many applications are known in connection with the production of foodstuffs (e.g. in the production of cheese).

It has been found that the use of the compositions to which the invention relates can have advantages over the use of inorganic phosphates or sugar phosphates when it comes to interaction with organic cations. This can be illustrated by a description of the interaction of phosphates with cetyl-trimethyl-ammonium bromide (CTAB).

When a 20% solution of trisodium phosphate or disodium phosphate is added to a 7% solution of CTAB in water, no precipitation can be observed. Dilution of the mixture with water to a solids content of approx. 1% causes no precipitation, and there is also no precipitation when acidifying with phosphoric acid. When calcium ions are added, a gel is obtained, probably as a result of the formation of calcium phosphate.

When a 40% solution of calcium sucrose phosphates which are mainly

substantially free of inorganic phosphates (e.g. the substance previously in

the letter is designated as composition C), a 7% solvent is added

of CTAB in water, no precipitation is obtained. A dilution of the mixture with water to a solids content of approx. 1%, however, gives a certain cloudiness and a limited flake formation.

When a 40% solution of a composition consisting of calcium sucrose phosphates in complex with inorganic calcium phosphate (e.g.

the substance that was earlier in the preparation designated as composition A),

if a 7% solution of CTAB in water is added, a slight cloudiness is obtained.

Dilution with water to a solids content of approx. 1% gives in this case

a rich dispersion that is relatively stable. It can be shown that the solid phase consists mainly of a compound of inorganic calcium phosphate and cetyl trimethyl ammonium sucrose phosphates.

These observations highlight the advantageous aspects of the connection of

an inorganic phosphate with sucrose phosphates in terms of forming a dis-

perfused solid phase from an organic cation. This may be of value in such applications as protein precipitation or the formation of a water-insoluble dispersion of an organic cation (in dilute solution). Various disinfecting, plant killing or fungicidal substances consist, for example, of

of organic molecules that can exist in solution as cations. effect-

tivity of these agricultural chemicals is sometimes limited due to the fact that they are water-soluble and are removed by rain. By suitably combining such chemicals with the compositions to which the invention relates, it is possible to obtain stable soluble, concentrated solutions. By suitably diluting the solutions (which can be carried out during spraying) it is possible for the chemical to form an insoluble dispersion with an increased duration of action on the plants or animals. This property, which is due to the complex interactions between the sugar phosphates, inorganic phosphate and organic cations in solution, is a new expression of the applicability of

the controlled solubility properties which are characteristic of the compositions whose preparation the present invention is based on.

Claims (1)

Process for the preparation of a complex compound in solid form or aqueous solution consisting of two components a and b, ie component a is at least one salt of a sugar phosphate and component b is at least one inorganic phosphate of a polyvalent metal cation which will usually form a substantially insoluble phosphate, and which is selected from the cations 2+ 2+ 2+ 2+ .T .2+ 2 + _ 2+ 3+A1 3+ .... Ca , Cu , Mn , Zn , Ni , Sn , Fe , Fe and Al , while the aforementioned compound is such that when the total sugar phosphate and inorganic phosphate dissolved in water exceeds 5 parts by weight per 100 parts by weight of water, there is at least 2% by weight of component b calculated on the weight of component a in solution at ambient conditions, characterized in that a solution of components a and b is prepared with a pH value that is not significantly lower than 7, and that the above-mentioned complex compound which is thereby formed is recovered from the solution, e.g. by using a precipitation with alcohol, the special case where the solution is prepared by phosphorylating one or more sugars in the presence of a calcium oxy compound in a stoichiometric ratio is excluded.