DE2260785A1 - Prepn of hydroxyethyl starches - using organic base catalyst useful as blood serum extenders - Google Patents

Abstract

By using org. bases as the catalyst, starches or partially hydrolyzed starches (mol. wt. of anhyd. glucose unit = 162) are reacted with hydroxyethylating agents in the presence of alkalis to give hydroxyethyl starches (I). In an example, 0.2 g pyridine and 4.05 g sol. starch were dissolved in 30 ml. H2O contg. 0.5 g NaOH, mixed at 40 degrees during 4 hr. stirring with 3.7 ml ethylene oxide, stirred further 1 hr. neutralized with ion-exchange resins, and the filtrate distd. at 40-50 degrees and mixed with iso-PrOH to give 4 g (I) (DS = 0-78 and II/III = 3.89).

Description

Process for the preparation of hydroxyethyl starch in the 6-position of the glucose ring is substituted by many hydroxyethyl groups.

The present invention relates to a method for producing Hydroxyethyl starch, which has many hydroxyethyl groups on carbon atom 6 of the glucose ring is substituted. The present Procedure differs in this of known processes where a hydroxyethylating agent, e.g., ethylene oxide, ethylene chlorohydrin or the like with starch or partially hydrolyzed starch (the molecular weight of the Anhydroglucose unit thereof is 162) simply in the presence of a catalytic Amount of sodium hydroxide is reacted to produce hydroxyethyl starch, which is on Carbon atom 2 of the clucose ring is substituted with many hydroxyethyl groups.

The hydroxyethyl starches produced by the process according to the invention are more effective as plasma stretching agents than hydroxyethyl starches that are on the carbon atom 2 of the clucose ring contain more hydroxyl groups and according to the known method have been manufactured.

The hydroxyethyl starches obtained by the process according to the invention are represented by the formula below.

The present invention thus relates to a method of manufacture of hydroxyethyl starches in the 6 position of the glucose ring, as indicated by the Formula shown contains many substituted hydroxyethyl groups.

In the past. Years, blood substitutes, especially plasma diluents, has been used to a great extent, this is due to the increase in surgical operations and the frequent occurrence of traffic accidents. Dextran-40 and dextran-70, the plasma diluents currently in use have low antigenic activity, which often causes fever and critical allergy reactions, z. Urticaria, and the inclination causes bleeding when the diluent is transferred in large amount. on the other hand was of the hydroxyethyl starches, which in 1934 by W. Ziese (Z. Physiol. Chem., 299, 213, (1934)) reported that they were used as plasma diluents are suitable. In this regard, see Gegenheim et al. 1957 (Arch.Int.

Pharmacodyn., 111, 353, (1957)).

The hydroxyethyl starches are made by reacting the ethylene oxide with soluble starch produced in the presence of a cataltic amount of alkali. Although it has been difficult to find out exactly where the hydroxyethyl groups are are substituted in the clucose ring of the starch produced, but have in the last Research conducted over time has shown that them preferably are attached to the secondary alcohol in position 1 of the clucoserine.

In particular, it has been found that the resulting ratio of 2-hydroxyethylglucose (hereinafter referred to as "2-O-HEG" for short) to 6-hydroxyethylglucose (hereinafter referred to as "6-O-HEG" for short) namely the ratio 2-O-HEG / 6-O-HEG according to Belder et al. (Carbohyd. Res., 10, 391 (1969)) 5.20 according to Sivastava et al. (Starke, 21, 181 (1969)), 5.50 or according to Bollenbach et al. (Cereal, Chem., 46, 304 (1969)) is 5.54. From this it is understandable that a larger number Hydroxyethyl groups substituted in position 2 than in position 6 of the glucose ring are.

On the other hand, based on the studies on the enzyme activity von Amvlase, with regard to methyl ether starches, reports that compounds disclosed in the position 6 of the clucose ring carry many substituents, an enzyme reaction are relatively more accessible than those with many substituents in Have position 2 of the fllucoserinps (Y. Matsushima et al., J, Biochemi., 64, 73 (1958) ).

On the basis of these investigations it was further found that hydroxyethyl starches, the many hydroxyethyl groups on the secondary alcohol in position 2 of the clucoserino (e.g. starch with a 2-O-HEG / 6-O-HEG ratio of 5.5) contain substituted in the Comparison with hydroxyethyl starches, which have a relatively larger number of hydroxyethyl groups on the primary alcohol in position 6 (e.g. starch with a 2-O-HEG / 6-O-HEG ratio von O, 8S) contain a different behavior with regard to α-amylase demonstrate. In particular, it was found that when comparing substances with the same Degree of substitution the latter hydroxyethyl starches of an enzyme reaction in vitro More accessible are around essentially the same level of concentration in the blood in the initial stage in vivo.

The latter strengths are eliminated faster and during one held back for a much shorter time compared to the long hold back period (2-3 Weeks), as is generally the case with conventionally manufactured Strengths are used. It has been found that according to the invention Hydroxyethyl starches produced by the process have excellent properties for them Have application as a plasma extender. Accordingly, it was searched for, hydroxyethyl to maintain strengths1 which have many substituents in position 6 of the clucose ring.

It was used in amounts corresponding to the amount of starch or the alkali partially hydrolysed starch (molecular weight of the anhydroglucose unit 162) used and surprisingly found that the application of alkali in a Amount of at least 1, corresponding to the molar ratio, (i.e. the alkali was as Reagent, but not as a catalyst in accordance with the customary processes used) allows the production of hydroxyethyl starches in position 6 of the clucose ring in proportions corresponding to the amount of alkali used Have substituents. In this way it became possible to produce hydroxyethyl starches, which have the desired molar ratio of 2-O-HEG to 8-O-HEG.

Authentic samples of Glucose (II), 2-O-HEG (III), 3-O-HEG (IV) and 6-O-HEG (V). The au @ ent table Samples were similarly replaced by the trimethylsilyl radical (e.C. Sweeley et al. Jan.

Chem. Soc., 85, 2497 (1963)). With the help of gas chromatography a test system was set up for each component. So were the hydroxyethyl starches (I), after being hydrolyzed with mineral acid, trimethylsilylated.

The proportions of the resulting components were determined in comparison with the authentic samples with the aid of cachroratography. 6th C2oN 6th / CH OH 4th Efo 2 GlucoE; e (PI) 1 H. 0 OH l ocH2cU2Oll II - olysis r-> wdrolysis T-LC 3-0-HBb (IV) ,, CH20CH2CH2oe 0 011 HO ½ll H0 C l) H 6-0 kEG (V) From the above hydroxyethyl starches, those exhibiting a molar ratio of 0.5 to 10.0 for 2-O-HEG / 6-O-HEG were selected to conduct experiments in the living body of rabbits. As a result, it was found that the hydroxyethyl starches which have more substituents in the 6-position of the glucose ring than those prepared by the known processes are more useful as plaque diluents than those having a 2-O-HEG / Have a 6-O-HEG ratio of 0.5 to 2.0. Among other things, it was confirmed that they are particularly excellent.

This is due to the difference in properties.

While the hydroxyethyl starches, the substituents on the carbon atom 2 of the glucose ring have such modified properties that the substituted glycoside bond of position 2 completely free of enzymatic If decomposition is or is extremely resistant to it, the elycoside bond can the position 6 in hydroxyethyl starches with a relatively larger number are gradually decomposed by substances in position 6 of the glucose ring, although they are resistant to decomposition.

To produce hydroxyethyl starches that have a molar ratio of the resulting Hydroxyethyl groups in position 2 to those in position 6 (2-O-HEG / 6-O-HEG) are substituted, from 0.5 to 2.0 have at least 2 moles of alkali 1 mole of starting starch or partially hydrolyzed starch (the Molecular weight of the anhydroglucose unit is 162) used Alkali during the reaction between starch and ethylene oxide is corresponding to the calculated below equation. The ratio of the components, i.e. the 2-O-HEG / 6-O-HEG Ratio of hydroxyethyl starch, that of the molar ratio of alkali to starch. is shown in Table 1. The table shows that, as already described the use of alkali as a reactant, but not as a Catalvsator according to the known process for the production of hydroxyethyl starches leads, which have many Subst @@ uenten in position 6 according to the amount of alkali. Furthermore, the table shows that the molar ratio of alkali to starch is at least 2, () must be in order to achieve the above ratio of 0.5 to 2.0, the special is suitable for use as a plasma extender.

162 NaOH amount (g) x = molar ratio starch amount (g) 40 where 162 is the Molecular weight of an anhydroglucose unit and 40 that of sodium hydroxide.

Table 1 molar ratio molar ratio degree of substitution with alkali / starch 2-O-HEG / 6-O-HEG hydroxyethyl groups 0.1 10.8 0.68 0.2 9.8 1.06 O.5 5.9 1.13 1.0 4.0 0.94 2.0 2.0 0.87 5.0 0.80 0.58 7.0 0.5 0.43 If potassium hydroxide is used instead of If sodium hydroxide is used, similar results are obtained.

Table 1 gives the resulting molar ratios of 2-O-HEG / 6-O-HEG and the degree of substitution (hereinafter simply referred to as "SG"), the using a constant amount of starch and ethylene oxide and by varying the amount of alkali used can be obtained. SG is the faction of the substituted Residual glucose. It is carried out according to the method of Morgan et al. (Ind.Eng.Chem.Anal.Ed., 28, 500 (1946)).

For comparison, constant amounts of starch and alkali were used used, the changes in the molar ratio of 2-O-HEG / 6-o-HEG according to the differences in the amount of ethylene oxide introduced (i.e. differences in the SG values) to observe. However, no changes were found.

Examples of starch or partially hydrolyzed starch that are used as starting material for the process according to the invention Grain starch, glutinous rice starch, wheat starch, potato starch, waxy corn starch, soluble starch, thin-boiling starch and the like. Particularly preferred are starches with a high amylopectin content. The alkali used in the process according to the invention preferably atrium hydroxide, potassium hydroxide and derpl. are used while alcoholates, e.g., methylate and ethylate, are also usable. Examples of hydroxyethylating agents are ethylene oxide, ethylene chlorohydrin and derp, 'l.

Furthermore, regardless of the alkali concentration used a catalytic amount of an organic nose is added to the reaction system, the molar ratio of 2-O-GEG / 6-O-HEG by 20 to 40% compared to the case reduce, in which di.e organic base is not used.

It is believed that this effect of hydrogen bonding is the catalytic Amount of organic base to the hydrogen atom of the active hydroxyl group in the Position 2 of the strengths is attributable to what the substitution of the Hydroxyläthvlions in position 2 hindered.

The catalytic amount of the organic base is generally an amount understood to be not more than 0.5 mole per mole of the starting material starch used or partially hydrolyzed starch (the molecular weight of the Anhvdrop, the glucose unit of which was 162). Examples of Oroan bases, which are used for the inventive method are: guanidine, pyridine, Cyclohexylamine, ethylenediamine, triethanolamine, monoAthanolamine, aniline, phenylenediamine, Morpholine, piperidine, pyrrole, piperazine, phenylhydrazine, i-urea, methylamine, Ethylamine, trimethylamine, triethylamine, semicarhazide, pyrrolidine, aminoguanidine, Aminophenol and derpl.

Usable organic bases are not limited to these examples. Any organic bases that are effective can be used as long as they are no adverse effect, e.g. B.

Hydrolysis of the resulting hydroxyethyl starches, cause, table 2 shows specific results obtained with or without the use of bases as catalysts were obtained.

Table 2 NaOH, used @ t used pyridine molar ratio amount SG 2-O-HEG / 6-O-HEG g mole g mole 0.2 0. @ - - 0.89 8.52 0.2 0.2 0.2 0.1 0.72 6.21 0.5 0.5 - - 1.13 5.90 0.5 0.5 0.02 0.01 0.97 4.62 0.5 0.5 0.1 0.05 0.83 4.16 0.5 0.5 0.2 0.1 n.78 3.89 0.5 0.5 0.6 0.3 0.24 4.27 0.5 0.5 2.0 1.0 0.089 4.36 1.0 1.0 - - 0.94 4.00 1.0 1.0 O.2 n, l 0.81 3.21 The number of moles in Table 2 is given as a molar ratio in terms of the number of moles of 4.05 g of soluble starch used as the starting material is used when the latter is given the value 1.

Table 2 indicates that the use of the organic base in excess via a catalytic amount an adverse effect on the molar ratio of the resulting components as well as exerts on the SG value, this is likely on the reaction of the hydroxyethylating agent with the excess amount of organic base. The accordingly is it alright, to use the organic base in a catalytic amount as described above, i.e. in an amount of less than 0.5 mole per mole of the starting material Strength. Preferred results are achieved when they are in a ratio of about 0.1 mole can be used.

A suitable amount of an orange rabbit salt can be used in place of the catalytic amount of the organic base used to make hydroxyethyl starches to produce a much larger number of substituents in the position 6 have al in the case where the alkali is used alone.

Examples of inorganic salts are: sodium nitrite,: sodium hydrogen phosphite, Sodium phosphite, aluminum chloride, lithium chloride, titanium chloride, iron (II) chloride, Manganese (II) chloride, potassium cvanate, potassium chlorate, sodium chloride, sodium chromate, Sodium perchlorate, sodium hypophosphite, manan (II) bromide, sodium nitrate, sodium hypophosphate, Sodium carbonate, sodium bicarbonate, sodium pyrosulfite, sodium pyrosulfate, boric acid, Metaboric acid, aluminum iodide, sodium borate, aluminum sulfate, potassium aluminum sulfate, Sodium thiosulfate, sodium sulfate, magnesium sulfate, potassium phosphate, disodium hydrogen phosphate, sodium phosphate, and the like. The inorganic salts are not limited to these examples. It all inorganic salts can be used in the same way, provided that they are effective and have no adverse effect on the source material and the hydroxyethyl starch.

Of the examples given, lithium chloride, Aluminum chloride, sodium sulfate, sodium thiosulfate, magnesium sulfate, sodium chloride, Disodium hydrogen phosphate and the like are used.

Specific results obtained with or without the use of the inorganic Salts obtained are shown in Table 3. It is obvious that the above effect will be caused by the inorganic salts.

Table 3 Starting material (soluble NaOH Na2SO4. SG molar ratio liche Starch) 2-O-HEG / 6-O-HEG 1OH2O g g mol g mol 4.05 2.0 2 - - 0.87 2.04 4.05 2.0 2 8 1 0.80 1.53 4.05 2.0 2 16 2 n.93 1.23 4.05 2.0 2 32 3 0.78 0.85 Although the invention Process is usually carried out in an open system, the reaction can also be carried out in a closed system, if necessary, e.g. if it is desired the Sr value of the hydroxyethyl groups to improve.

From the above it can be seen that the method according to the invention is capable of supplying hydroxyethyl starches containing a relatively large amount of Have substituents in position 6. The process is simple and proportionate cheap.

Furthermore, the hydroxyethyl starches obtained have excellent effects as pharmaceutical products, particularly as plasma diluents, all of them are superior to such previously featured products.

Example 1 4.05 g of waxy corn starch is dissolved in 80 ml of water, the 5th p contains sodium hydroxide, and 3.2 g of ethylene oxide are suspended for 3 hours introduced into the resulting suspension at 400C in the gaseous state. To after the ethylene oxide is introduced, the reaction is continued for 2 hours at the same time Temperature continued with stirring. After cooling become the reaction mixture Add RO ml of a cation exchange resin while continuing to stir. The resin is then filtered off. Then acetone becomes the resulting filtrate given to precipitate the desired substance (i.e. hydroxyathvl starch). The resulting precipitated product is collected by filtration. It is washed out with acetone / ethanol and provides 4 g of hydrolyte starch (SG = 0.58) as colorless crystals, which form a 2-O-HEG / 6-O-HEG Have ratio of 0.78.

Example 2 10 g of waxy corn starch are partially with 12 ml of a 0.5 to 1 normal hydrochloric acid hydrolyzed for 5 to 7 hours to make 9.8 g of a thin boiling point To make starch. 4.05 g of it are then dissolved in 30 ml of water, the 2.8 p. Includes K011.

3.2 g of ethylene oxide are under atmospheric pressure at 30 ° C. for 3 hours introduced as a gas into the solution. After cooling, it becomes a cation exchange resin added to the reaction mixture to remove the alkali, the resin is then filtered off, The filtrate is concentrated, then acetone is added to carry out the precipitation perform. The resulting precipitated product is washed with acetone / ethanol, 4.1 g of hydroxyethyl starch (SG = 0.75) as a colorless powder with a 2-O-HEG / 6-O-HEG Ratio of 1.6 can be obtained.

Example 3 0.5 g of sodium hydroxide are dissolved in 30 liters of water. 0.2 g pyridine and 4.05 z soluble starch will remain in the alkaline solution solved. Become this mixed solution 4 hours at 40 ° C below Stirring 3.7 ml of gaseous ethylene oxide initiated. I) the reaction mixture is then stirred at the same temperature for another hour. After the cool down a cation exchange resin was added to the reaction mixture to neutralize it. The cation exchange resin is then filtered off and the filtrate at 4r) - 50 ° C removed.

Isopropyl alcohol is then added to the resulting residue knock down the desired product. The precipitate is collected by filtration obtained, washed thoroughly with acetone / ethanol and dried, with 4 g of hydroxyethyl starch (SG = n, 78) as a colorless powder with a 2-O-HEG / 6-O-HEG molar ratio of 3.89 can be obtained.

The reactions were carried out in the same way, with the exception that the catalytic amount of pvridine was varied.

The results are shown in Table 2.

Example 4 To an aqueous solution containing 0.5 @ sodium hydroxide, 0.34 ml of triethylamine are used as a catalyst and then 4.05 g of thin-boiling starch given, 3.7 ml of ethylene oxide are then 4 hours at 40 ° C while stirring the mixture initiated as @as, then stirring is continued at the same temperature for 2 hours continued. After cooling down, it will react mixed with one Treated cation exchange resin for neutralization. Under reduced pressure is distilled at 40-50 ° C., a residue being obtained. This becomes acetone given- to cause the precipitation. The resulting precipitate is made by filtration obtained, washed thoroughly with isopropyl alcohol and dried, with 4 g. Hydroxyethyl starch (SG 0.286) as a colorless powder with a 2-O-HEG / 6-O-HEG molar ratio of 3.21 There were reactions among the. same conditions as in example 4 carried out using catalysts other than triethylamine was. These results are in the table. 4 reproduced. The reaction products were obtained as colorless powders in yields of approximately 90%.

Table 4 NaOlt Organic Base Molar Ratio (Amount) (Amount) SG 2-O-HEG / 6-O-HEG g mol type g (ml) mol 0.5 0.5 - - - 1.13 5.90 0.5 0.5 guanidine 0.15 0.1 0.53 4.50 0.5 0.5 ethylan-0.15 0.1 0.69 4.58 diamine 0.5 0.5 30% aqueous (0.5) 0.1 0.59 3.21 solution

of trimethylamine 0.5 0.5 morpholine 0.11 0.05 0.40 4.66 0.5 0.5 trihydroxy 0.18 0.05 0.49 4.69 ethylamine 0.5 0.5 ethylamine (0.23) 0.1 0.59 4.43 0.5 0.5 aniline 0.12 0.05 0.39 4.50 0.5 0.5 thiourine 0.19 0.1 0.33 4.54 substance 0.5 0.5 piperidine (0.24) 0.1 0.68 4.00 0.2 0.2 - - - 0.89 8.52 0.2 0.2 piperidine (0.24) 0.1 0.77 5.91 0.2 0.2 triethyl (0.34) 0.1 0.72 6.44 amine 1.0 1.0 - - - 0.94 4.00 1.0 1.0 piperidine (0.24) 0.1 0.63 2.89 1.0 1.0 triethyl (0.34) 0.1 0.74 3.20 amine The number of moles of Table 4 is referred to as a molar ratio to the number of moles of 4.05 R is the thin-boiling starch that is used as the starting material, the the latter is given the value 1.

The results clearly show that regardless of the alkali concentration the use of a catalytic mixture of an organic base, the molar ratio 2-O-HEC / 6-n-HEG decreased by 20-40% compared to the case where it was not used will.

Example 5 In 30 ml of water, 2 g sodium hydroxide and then 16 g of sodium sulfate dissolved. 4.05 g of soluble starch are added to this solution. Then 3.7 ml of ethylene oxide are stirred in the course of 4 hours in the gaseous State initiated into the Cemisch at 400C. After that it is still at the same temperature Stirred for 1 hour. After the reaction, the reaction mixture is added by adding a Cation exchange resin made acidic (not higher than pH 1). Then will continue an anion exchange resin was added for neutralization. After removing both Resins from the neutralized reaction mixture is the neutralized mixture under concentrated under reduced pressure at 500C, approximately 60 ml of isopropyl alcohol or acetone is added to the concentrated mixture to precipitate the desired product (Hydroxyethyl starch). The precipitation is through Filtration separated and washed thoroughly with acetone-ethanol. 4 g of Hydroxyathyis strength (sr, = 0.93) as a colorless powder with a 2-O-HEG / 6-O-HEG molar ratio of 1.23 (see, Table 3).

Example 6 There are reactions under the same conditions as carried out in Example 5, using inorganic salts other than sodium sulfate will. The results are compiled in Table 5, the products are listed as colorless crystals were obtained in a yield of about 90%.

Table 5 NaOH Inorganic Salts Molar Ratio (amount) (amount) sr, 2-O-HEG / 6-O-HEG g type g mol 2.0 lithium chloride 2.5 2.5 0.67 0.92 2.0 aluminum chloride 12.0 2 0.14 1.04 hexahydrate 2.0 sodium thiosulfate 12.0 2 0.23 1.15 pentahydrate 2.0 Potassium cyanate 5.0 2.5 0.76 1.03 2.0 Potassium sodium 14.0 2 0.54 1.18 phosphate heptahydrate 2.0 disodium hydrogen phosphate hepta- 13.4 2 0.65 1.21 hydrate 2.0 sodium carbonate 4.0 1.5 0.74 1.42 Expressed in units of molar ratio, based on to -the number of moles of 4.05 g of soluble starch used as the starting material which is given the value 1.

Claims (4)

Claims 1) Process for the production of hydroxyethyl starches, which in position 6 of the glucose ring, as shown in the following formula, contain many hydroxyethyl groups substituted, characterized in that hydroxyethylating agents are reacted with starches or partially hydrolyzed starches (the molecular weight of the anhydroglucose unit thereof is 162) in the presence of at least 2 moles of alkali per mole of the starch, 2) Process for the preparation of hydroxyethyl starches of the following formula which contain many substituted hydroxyethyl groups in position 6 of the alucoserings characterized in that the starches or partially hydrolyzed starches (the molecular weight of the anhydroglucose unit thereof is 162) are reacted with the hydroethylating agents in the presence of alkali and organic bases are used as the catalyst. 3) Process for the preparation of hydroxyethyl starches of the following formula, which contain many substituted hydroxyethyl groups in position 6 of the glucose ring, characterized in that the starches or partially hydrolyzed starches (the molecular weight of the anhydroglucose unit thereof is 162) are reacted with the hydroxyethylating agents in the presence of alkali and inorganic salts. 4) Method according to the preceding claims, characterized in that that it is carried out under the conditions of the examples