DE1518587A1 - Process for the production of phosphoric acid esters from polymers containing hydroxyl groups - Google Patents

Description

Process for the preparation of phosphoric acid esters of hydroxyl-containing Polymers The invention relates to the production of homogeneously esterified, water-soluble Phosphoric acid esters of polymers containing hydroxyl groups, for example polysaccharides or synthetic polymers such as polyvinyl alcohol.

It is known, for example, to phosphorylate dextran, whereby one phosphorus oxychloride (POCl3) is generally used as a phosphorylating agent. as Solvent or reaction medium one uses anhydrous pyridine, which at the same time acts as an acid-binding condensation agent. Highly hydroxyl containing polymers, e.g. B. unsubstituted polysaccharides, but are not or only strong in pyridine soluble in the degraded state. When using pyridine one therefore usually obtains cross-linked or strongly degraded phosphoric acid esters of polysaccharides.

Attempts have therefore already been made, for example, dextran in water Solution using alkali as a hydrogen chloride binding agent phosphorylate.

This process has the disadvantage that with highly concentrated alkali must be worked, with a strong hydrolysis of the phosphorus oxychloride occurs.

Because of this and because of the low reaction temperature required of about + 10 ° C, the degree of phosphorylation achieved is only low.

The process according to the invention is used as a solvent or swelling agent for the polymers formamide. It is already-known that formamide z. B. for strength has a better solvency than water and that acylations of neutral and acidic polysaccharides with acidic anhydrides in formamide are possible. In younger Time has shown that phosphorus oxychloride is an ionic addition compound with formamide of the formula [H2N = CH-O-P (= 0) Cll 01 ", which is very reactive.

The inventive method does this in formamide with POC13 compound formed in a hitherto unknown manner for the phosphorylation of use of the hydroxyl-containing polymers present at the same time. The used Polymers in anhydrous formamide at room temperature or by brief heating dissolved with stirring. To avoid a strong evolution of hydrogen chloride or any chain degradation caused by this can be used as the acid-binding base morpholine be added in sufficient quantity. Pyridine is suitable as an alkaline agent not, as it suppresses the solubility of the polymer in formamide, and therefore more networked products are formed. In addition, it quickly darkens of the reaction mixture as a result of side reactions.

To the solution or highly swollen suspension of the polymer in formamide or formamide-morpholine mixture is cooled with ice water and vigorous stirring the phosphorus oxychloride was added dropwise. At about + 5 ° C there is still no noticeable Phosphorylation of the polymer.

If the reaction mixture is warmed to room temperature or above, finds one within about 30 minutes significant esterification of the polymer instead. As a result of the dehydrating effect of POCl ~ 3 ^ on formamide a small amount of hydrogen cyanide is formed, if the addition of a sufficient amount of base just as the resulting hydrogen chloride is largely bound.

By varying the reaction temperature and the reaction time, you can the degree of phosphorylation can be arbitrarily influenced.

The esterification reaction is carried out after the desired reaction time Addition of excess methanol to the reaction mixture is stopped, causing the phosphorylated reaction product is flocculated at the same time. Is cleaned the product by reprecipitation from aqueous solution with methanol or from alkaline soda Solution with formation of the sodium salt.

Ion exchange membranes or gels which still contain free hydroxyl groups in this way can be added gently and easily with phosphoric acid are esterified i, whereby their exchange capacity increases or their selectivity is changed.

Phosphoric acid esters of polymers containing hydroxyl groups can be used for manifold technical purposes are used, such as. B. as a thickener, Gel formers with certain cations, ion exchangers, intermediates for others Implementations. In addition, certain phosphoric acid esters can have therapeutic applications Find.

Example 1 3.0 g of dried guar gum in 300 ml of distilled water. Formamide swollen by heating and dissolved except for a small, highly swollen portion. The mixture is cooled to about + 5 ° C and 17 ml of POCl3 are added dropwise with vigorous stirring and with cooling of the reaction mixture so that the internal temperature does not exceed + 15 ° 0 increases.

The mixture is then heated to 40 ° C for 1/2 hour while stirring, with strong foaming due to the development of HCl with a low HCN content. By access. be of excess. Methanol, the reaction is stopped and that Reaction product flocculated. The product is worked up and cleaned by swelling or dissolving in water several times with the addition of a little soda lye and precipitation with methanol. The resulting in addition to a highly satisfactory gel portion water-soluble guaranophosphoric acid ester has a P content of 17.8%, which is one Degree of substitution of 2.25, calculated on mono-sodium salt.

Example 2 5, 3 g of dried guar gum are distilled in 400 ml. Shape- -, amide geauollen by heating and largely dissolved.

One adds to the binding the resulting in the subsequent reaction Add 14.0 ml of morpholine, cool the mixture to about + 5 ° C and drop 30 ml POC13 with vigorous stirring and with cooling of the reaction mixture so that the internal temperature does not exceed + 15 ° C nteic-t; Duration approx. 1 hour. Afterward the mixture is stirred for a further 1/2 hour at room temperature (22 ° C).

The reaction is stopped by adding an excess of methanol, whereby the reaction product flocculates.

Further purification can be carried out as in Example 1.

P content of the largely water-soluble, highly viscous product : 5.85, which corresponds to a degree of substitution of 0.38, calculated on the monosodium salt.

Example 5 9.5 5 g anhydrous polyvinyl alcohol powder (PVA 90-98) are in 500 ml of dist. Formamide by heating to about 120 ° C to a viscous Sol solved. It is cooled and 250 ml of morpholine are added to bind the acid formed and allows 58 ml of POCl3 to be added while vigorously stirring the mixture, the The reaction mixture is kept at a temperature of +5 to +15 ° C by cooling will. The mixture is then heated to 60 ° C. with stirring for 1 hour and then thoroughly stirred Addition of methanol stopped the reaction and flocculated the product. The cleaning can wi. e in example 1. The completely water-soluble phosphoric acid ester obtained of the polyvinyl alcohol has, as Mohosodium salt, a P content of 7.55%, the one 14, 2 percent Esterification corresponds.

Example 4 10 g of dextran are dissolved in 800 ml of dist. Formamide by embracing broke to swell, with mostly solution occurring. To bind the emerging Acid do you add? Add 80 ml of Mornholin, cool to about + 5 ° C and leave under vigorous Stir and cool 160 ml of POC15 dropwise so that the Internal temperature does not rise above + 15 ° C (duration oa.

1 hour). The mixture is then left for 3 hours at room temperature (22 ° C) stirred further. The reaction is made by adding an excess of methanol canceled, the reaction product flocculating. Further cleaning can be done as in Example 1 take place. The product obtained in this way has a phosphorus content of 2.8 %. The yield is 10e2 g.

Claims (1)

Claims 1) Process for the preparation of phosphoric acid esters hydroxyl group-containing polymers with phosphorus oxychloride, characterized in that that to the solution of the hydroxyl-containing polymer in formamide phosphorus oxychloride at temperatures of 0-15 ° C is added and then the reaction mixture is heated 2) Method according to claim 1, characterized in that the acid-binding agent Mbrpholine added.