CH290145A - Process for the preparation of sulfuric acid esters of xylan. - Google Patents

Description

  

  
 



  Process for the preparation of sulfuric acid esters of xylan.



   It is known that the sulphuration of polymeric hexoses (namely cellulose, starch, glycogen, pectin and chitin) with a chlorosulphonic acid-pyridine mixture results in reaction products which, depending on the choice of the starting product, are able to delay the natural coagulability of the blood or entirely cancel.



     Sulfuration products of pentosans, for example xylan, are not yet known. Nor could it be foreseen that sulfurous products of the pentosans would delay or abolish blood clotting in a manner similar to that of heparin.



   It has now been found that the sulfurization of pentosans under various conditions gives rise to reaction products which have an anti-coagulant effect. It has also been found that the extent of the anticoagulant effect depends on the conditions under which the sulfurization is carried out.



     Depending on the preconditions, products with different viscosities arise, from which it can be concluded that they have different molecular sizes. During the sulfurization, the pentosan molecules are partially broken down, i.e. partial depolymerization. The same process can also be achieved by pretreating the pentosans before the actual sulfurization. To a certain extent, the anticoagulant effect depends on the viscosity and thus on the molecular size. The optimum anticoagulant effect is at a degree of polymerization of
10 to 100, preferably 20 to 80.

   This can be done either by controlling sulfurization or by pre-sulfurization mining.



   The subject of the patent is now a process for the production of a sulfuric acid ester of partially degraded xylan, wel ches is characterized in that starting from xylan, on the one hand a degradation and on the other hand an ISulfierung carried out, in such a way that the product obtained a
Degree of polymerization between 10 and 100 has.



   The sulfurization product obtained in this way is an amorphous, readily water-soluble powder which is insoluble in alcohol. It forms neutrally reacting alkali salts which are easily soluble in water. The barium salts are sparingly soluble. The aqueous solutions are resistant to boiling and light. The product is able to delay or completely stop the coagulation of natural blood (mammalian blood or men’s blood) in vitro as well as in vivo.



   1. In vitro test:
In a record syringe with 0.2 cm3
3.8 percent sodium citrate solution is charged, 0.8 cm3 of blood is drawn up and mixed well. 0.1 ems of this mixture is placed in a small test tube; 0.2 cm3 distilled water are added in which the substance to be tested is dissolved. Hang in a 37 water bath for one minute. A 0.5 percent, precisely adjusted calcium chloride solution is blown in and the time from the beginning of the blowing in to the occurrence of coagulation is measured. Three individual samples give a value.



   A preparation with an sp / e value of 0.015 extends the human coagulation time from 2'35 "at a concentration of 5 y per cm3 to 7'43", at 2.5 y to 6'15 " No coagulation occurs for 2 hours at a concentration of 25 μg per cm of blood.



     2. In vivo test:
A rabbit is injected intravenously with 3 mg per kg and, after the normal coagulation value has been determined, the blood is taken 5 minutes after the injection and then every half an hour.



   A preparation with an Ssplc value of 0.015 doubles the coagulation time 4 hours after the injection.



   Examples:
1. 3 g of freshly reprecipitated xylan, which was obtained by extracting hardwood flour (in particular beech or birch wood) with 8 percent sodium hydroxide solution (Husemann, Journal f. Pract. Chemie 155, 38; 1940), are mixed with a mixture of 60 cm3 of pyridine and 14 cm3 of chlorosulfonic acid heated to 100 ° for 8 hours while stirring and, after cooling, poured into 1 liter of methanol.



  After washing out, it is dissolved with a little water, centrifuged, treated with 8 percent sodium hydroxide solution and precipitated by pouring into the 10-fold volume of methanol.



  Further purification by dialysis.



   The product obtained has a degree of polymerization of about 50.



   2. Before esterification, xylan is partially depolymerized by heating with 0.5N potassium bisulfate or an acid (for example hydrochloric acid). This reaction product is esterified as in Example 1, but at a temperature of 600. The degree of degradation is monitored by checking the dsple values. The dsple value of the finished sulfurized product is about half as large as that of the original xylan. By directing the degradation in a certain way, the optimum effect is achieved with good yield.



   The degree of polymerisation of the finished product can be greatly influenced by the duration of the heating with walium bisulphite or acid before sulphurisation. For example, when a xylan with an approximate degree of polymerization of 150 was heated in 0.5N potassium bisulfite for 24 hours, the degree of polymerization of the finished sulfurized product was approximately 30. When the xylan was broken down in exactly the same way for 2 to 3 days before esterification sulfurized products with a degree of polymerization around 20 are obtained.

 

Claims (1)

PATENT CLAIM: Process for the production of a sulfuric acid ester of partially degraded xylan, characterized in that, starting from xylan, on the one hand a degradation and on the other hand a sulphonation are carried out in such a way that the product obtained has a degree of polymerization between 10 and 100. The new product obtained is an amorphous, white powder that dissolves well in water, but does not dissolve in common organic solvents. It is characterized by a strong anticoagulant effect in vitro and in vivo as well. Process according to patent claim, characterized in that the sulphuration is carried out with a chlorosulphonic acid-pyridine mixture.