Method of obtaining water-insoluble sulphur-containing chitosan-based biomaterial
SUBSTANCE: invention relates to the field of organic synthesis. A method of obtaining a water-insoluble sulphur-containing chitosan-based biopolymer includes interaction of chitosan with a thiomethylating agent, preliminarily obtained by saturation of a formaldehyde solution with gaseous H2S, with molar ratio chitosan: formaldehyde: hydrogen sulphide 1:6:4, at a temperature of 60°C for 20-25 hours.
EFFECT: invention ensures obtaining the water-insoluble sulphur-containing chitosan-based biopolymer, which possesses a complexing activity to ions of noble metals (Pd, Pt).
1 ex, 1 tbl
The invention relates to organic chemistry, in particular to a method for producing sulfur-containing crosslinked derivative of chitosan (1), having the structural formula:
Sulfur-containing derivatives of chitosan can be used as a highly effective sorbents of heavy metals to wastewater treatment, extractants for the separation of rare and precious metals, as well as selective complexing agents.
It is known that chitosan and its derivatives are promising polysaccharide materials to create ion-exchange membranes used in ultrafiltration and dialysis, and their complexing ability can be used for selective extraction of some metals from seawater (Evert, Lnterface // USP, 2001, CH, No. 1, p.72-87.). Chitosan and its phosphate derivatives, in particular phosphate chitosan can be used as biocompatible materials (Wang X., MA J., Wang Y., He, B. // Biomaterials, 2001, V.22, No.16, P.2247), sorbents for the extraction of uranium (Sakaguchi T., Hirokoshi T., Nakajima A. // Agric. Biol. Chem., 1981, V.45, No.10, P.2191), chiral matrices to create a metal-complex catalysts (E. Guibal // Prog. Polym. Sci., 2005, V.30, No.1, P.71).
According to literature data, the chemical modification of chitosan can be carried out for all functional groups. Thus, the known method the floor is placed N,O-carboxymethyl-N,O-sulfotransferase chitosan (Zhao Xia, LV Zhihua, XU Jiamin, YU Guangli // Journal of Ocean University of Qingdao, 2003, V.2, No.1, P.69-74)with inhibitory activity against platelet blood:
There are ways of modification of chitosan solely by the primary amino group of the polysaccharide to obtain N-alkyl derivatives of chitosan. The method is based on the interaction of chitosan with aliphatic aldehydes by introduction of alkyl substituents on the amino group of the original polymer via Schiff's base (Keisuke Kurita, Satoko Mori, Yasuhiro Nishiyama, Manabu Harata // Polymer Bulletin, 2002, 48, 159-166). It was shown that with increasing alkyl radical increases antibacterial activity of derivatives of chitosan (Chun But Kim, Jang Won Choi, Heung Jae Chun, Suk Kyu Choi // Polymer Bulletin, 1997, V.38, No.4, P.387-393).
A method of obtaining sulfur-containing biopolymer by modification of chitosan component sulfur-containing agent with obtaining N-thiocarbamoylation [Aviston, Shubraska, Abelardo, Waaramaa, Ugetsu. Thiocarbamoylation - new sorbent with high capacity and selectivity for ions of gold (III), platinum (IV) and palladium (II). WPI. An. A series of chemical, 2010, No. 7, s-1276]. As the two sulfur-containing agent, a mixture of ammonium thiocyanate and thiourea, modified chitosan is carried out at a temperature of 130°C for at least 4 hours. About the TPC is subjected to cold extraction with water until a negative reaction to the thiocyanate ion.
The disadvantage of this method is the need for process modification of chitosan at high temperature, use as a sulfur-containing reagent thiourea and ammonium thiocyanate - deficient reagents.
A method of obtaining sulfur-containing biopolymer by modification of chitosan with formaldehyde and sulfur-containing reagent to obtain N-metilsulfate grafted derived hitozuma (D.J.Macquarria, Hardy, J.J.E. // Ind. Eng. Chem. Res., 2005, Vol.44, No. 23, P. 8499-8520).
As the sulfur-containing reagent is used thiol-mercaptohexanol acid HSCH2COOH.
In this way cannot be obtained stitched sulfur-containing derivative of chitosan (1).
Closest to the proposed technical essence is a method of obtaining sulfur-containing biopolymer consisting in the reaction of chitosan with formaldehyde and H2S in the ratio of chitosan : formaldehyde : hydrogen of 1:2:1, leading to a heterocyclic derivative of chitosan, forming a stable gel with water [Dzhemilev sea level, Rakhimov E.B., minlebaev A.B., Akhmetov V.R., Kunakova RV Application No. 2010122540/04.22.09.2010].
The known method cannot be obtained water-insoluble sulfur-containing derivative of chitosan, altausee property of the sorbent of metal ions.
The purpose of the invention is to obtain water-insoluble sulfur-containing biopolymer chitosan with complexing activity to ions of noble metals (Pd, Pt).
This goal is achieved by modification of chitosan myometrium agent obtained by saturation of an aqueous solution of formaldehyde gas H2S. the Modification is carried out by interaction of hydrochloric acid solution of chitosan and timetreasure agent at a molar ratio of chitosan : formaldehyde : hydrogen of 1:6:4 at a temperature of 0-60°C for 20-25 hours.
The reaction modification of chitosan proceeds according to the scheme:
obtaining water-insoluble crosslinked sulfur-containing derivative of chitosan (1), where n=300-1800.
The method is illustrated with an example.
Example 1. In a three-neck flask equipped with a stirrer and a bubbler, thermostated at 20°C, loaded the calculated amount of 37%formalin (0,03 mole), 30 minutes was barbotirovany hydrogen (derived from the estimated number of Na2S and HCl)to form dimethylurea mixture "CH2O and H2S". Then the reaction mass was added dropwise to 0.005 mole of chitosan (0.8 g)dissolved in diluted hydrochloric acid (0,365 g HCl in 8 ml of H2O) at a given temperature (0, 20, 60°C). The mixture was stirred is at a given temperature (0, 20, 60°C) within 24 hours. The reaction mass was neutralized with diluted NaOH solution to pH=7. The modified chitosan of the reaction mass was besieged by treatment with 70%ethanol in a volume of 150 ml, was added a few drops of concentrated NaCl solution to coagulate the polymer. The precipitated biopolymer was centrifuged and washed three times with 70%alcohol. The result was 1.26 g at 0°C, 1.32 g at 20°C and 1.38 g at 60°C sulfur-containing derivative of chitosan (1).
Characteristics of sulfur-containing derivative of chitosan (1)
Elemental composition. Found (percent): C, 40.54; H, 5.86; N, 6.3; S, 23.54. Calculated (%): C, 41.95; H, 5.59; N, 4.89; S, 22.37. IR spectrum, ν, cm-1: CL 529, 588 SL and 639 CL (C-S) 750, 1050, 1170, 1650, 2166, 2900, 3400.
IR spectra were obtained on a spectrophotometer "Specord 75IR" in suspension in vaseline oil. Elemental analysis of the compound (1) (C, H, N, S, O) was determined on the analyzer company Karlo Erba model 1106.
The optimal conditions for the modification process are: maintaining the molar ratio of chitosan : formaldehyde : hydrogen sulfide is 1:6:4; temperature 60°C, duration of 20-25 hours.
Reducing the number dimethylurea mixture is less than the molar ratio of chitosan : formaldehyde : hydrogen of 1:6:4, it leads to the formation of the target product. The increase in the number dimethylurea mixture is higher than the mole is E. the ratio of chitosan : hydrogen sulfide, equal to 1:4, leads to the formation side of the cyclic sulphur compounds. Lowering the process temperature below 60°C leads to a reduction of the yield of sulfur-containing derivative of chitosan (1). Increasing the process temperature above 60°C does not significantly affect the output (1). Reducing process time less than 20 hours leads to a decrease of the degree of functionalization of the biopolymer. The increase in the length of more than 25 hours is inappropriate.
The proposed method allows to obtain a water-insoluble sulfur-containing biopolymer chitosan with complexing activity to ions of noble metals (Pd, Pt).
For compound (1) were studied sorption properties for extracting ions of Pd (II) and Pt (IV) from hydrochloric acid solutions. The table presents the dependence of the distribution coefficients (Kd) and the degree of extraction (R) ions Pd (II) and Pt (IV) sample (1) from the original acidity of a solution at a concentration of [K2PdCl4]0=0.0237 M, [H2RtCl6]0=0.0185 M and the ratio of solid : liquid=1:300, τ=24 h revealed that the most effective sorbent extracts Pt(IV) from weakly acidic solutions. With increasing acidity of the aqueous phase up to 5 M HCl capacity of the sorbent is reduced.
|The dependence of coefficie the Ltd distribution and the degree of extraction of Pd (II) and Pt (IV) example (8) from the original acidity of a solution if [K 2PdCl4]0=0.0237 M, [H2PtCl6]0=0.0188 M, t:W=1:300, τ=24 h|
|CHClM||Pd (II)||Pt( IV)|
A method of obtaining a water-insoluble sulfur-containing biopolymer (1) based on chitosan, which consists in the interaction of chitosan with myometrium agent, prior saturation of the solution of formaldehyde in gaseous H2S, wherein the reaction is carried out at a molar ratio of chitosan : formaldehyde : hydrogen of 1:6:4 at a temperature of 60°C for 20-25 hours.
SUBSTANCE: skins of pond fish are flushed with cold flushing water during 10-15 minutes. They are crushed to the size of 2-3 mm. Water extraction is performed at the temperature of 40-45°C during 40-50 minutes at the ratio of crushed skins to water, which is equal to 1:1 at periodic mixing. Then, they are filtered; liquid fraction is dried in a spraying drier at the drier outlet product temperature of 60-65°C during 15-25 minutes so that hyaluronic acid is obtained. Solid fraction is subject to bleaching during 12 hours with hydrogen peroxide-salt solution that is prepared by mixing of 1 l of 3% hydrogen peroxide and 20 g of sodium chloride. Treatment of bleached solid fraction is performed with 1.0-1.2% solution of sodium hydroxide during 24 hours at the temperature of 20-25°C with further neutralisation of the obtained mixture with 3% boric acid solution. Treatment of swollen solid fraction is performed with Pancreatin ferment preparation solution taken in the quantity of 0.5-0.6% to the weight of solid fraction during 1.5-2.0 hours at the temperature of 37-40°C. Flushing of solid fraction is performed with cold flushing water for removal of Pancreatin residues so that collagen is obtained. The obtained collagen, depending on the purpose, is supplied for drying in drying chambers with forced air circulation at the temperature of 18-20°C during 12 hours and storage in dry ventilated rooms at the temperature of not higher than 20°C during 24 months or frozen to the temperature of minus 18 - minus 20°C and stored at the temperature of minus 18 - minus 20°C during 24 months. The liquid fraction dried in the spraying chamber is stored at the temperature of 0-4°C during 12 months or dissolved in physiological buffer solution.
EFFECT: improvement of the method.
2 dwg, 1 tbl, 1 ex
SUBSTANCE: production method of glucan-chitosan complex from yeast biomass of brewing waste involves mechanical and ultrasonic treatment of yeast biomass, destruction of proteins by treatment of the obtained suspension using alkali reagents with further extraction of a target product. As biomass, Saccharomyces living yeast is used. First, yeast is frozen to -15°C during 24 hours. After mechanical destruction, biomass is treated for 15 minutes at 20°C in an ultrasonic bath with frequency of an emitter of 35 kHz and voltage of 285 W. Biomass is acidified with chlorhydric acid till pH=5.5 and treated with ferment preparation in the amount of one pellet containing lipase - 3500 units of Ph.Eur., amylase - 4200 units of Ph.Eur. and protease - 250 units of Ph.Eur. per kilogramme of biomass in terms of dry substance; then, lipid components of yeast are removed. Fermentation is performed at t=20-29°C during 30-60 minutes. Destruction of proteins is performed at 55°C by means of a water bath during 60 minutes by treatment using 4% water solution of caustic soda at the ratio of yeast biomass and alkali, which is equal to 1:4. The medium is neutralised and hydrosol of glucan-chitosan complex is deposited by centrifugation during 10 minutes. The deposit is dried at t=55°C during 48 hours.
EFFECT: invention allows improving the quality of the obtained complex and its biological activity.
SUBSTANCE: invention relates to production of hydroxyalkyl derivatives of polysaccharides. The method of producing 2,3-dihydroxypropyl chitosan involves reacting chitosan with glycidol in the presence of hydrochloric acid with ratio glycidol:chitosan:hydrochloric acid = (2-6):1:1, at room temperature until a gel forms. The mixture is then heated at 55-65°C for 12-14 hours and the reaction mass is treated with water. The mixture is then deposited, subjected to hot extraction with water-soluble alcohols or ketones and dried.
EFFECT: invention simplifies the method of production and output of the end product and improves sorption properties of the compound.
1 tbl, 3 ex
FIELD: medicine, pharmaceutics.
SUBSTANCE: there are presented: using benzophenanthridine alkaloid salts for preparing therapeutic agents for treating tumours, wherein the alkaloid salt is found in the form luteic, phosphatidic or hyaluronic acid, the benzophenanthridine alkaloid salt with phosphatidic acid or hyaluronic acid, and a based pharmaceutical composition for treating tumours.
EFFECT: what is shown is cytotoxic activity of the sanguinarine salts according to the invention at least twice increased in all studied tumour cell lines in relation to the chloride salt; it is suggested to be caused by higher absorption by the tumour cells.
12 cl, 8 ex
FIELD: medicine, pharmaceutics.
SUBSTANCE: invention refers to a recovered imidised biologically compatible polymer functionalised by an imide group. The above polymer is selected from the group consisting of polyethylene oxide, partially or completely hydrolysed by polyvinyl alcohol, polyvinylpyrrolidone, polyethyloxazoline, polyoxypropylene oxide block copolymers (poloxamers and meroxapol), polyethylene oxide and poloxamine copolymer, carboxymethyl cellulose and hydroxyalkylated cellulose, polypeptides, polysaccharides, carbohydrates, polysaccharose, hyaluronic acid, dextran, heparin sulphate, keratan sulphate, chondroitin sulphate, heparin, alginate, gelatin, collagen, albumin, ovalbumin, complex polyphosphoesters, polylactides, polyglycolides, polycaprolactones, polyamides, polyurethanes, polyesteramides, polyorthoesters, polydioxanones, polyacetals, polyketals, polycarbonates, polyorthocarbonates, polyphosphazenes, polyhydroxybutyrates, polyhydroxyvalerates, polyalkylene oxalates, polyalkylene succinates, polymaleic acids, polyamino acids, polyvinyl alcohol, polyvinylpyrrolidone, polyhydroxy cellulose, chitin, chitosan, and copolymers, ternary copolymers, or combinations or mixtures of the aforementioned materials. Also, the invention refers to a composition for a tissue adhesive, a medical device and a pharmaceutical composition.
EFFECT: invention represents additionally modified or functionalised imidised polymers.
9 cl, 2 ex, 20 dwg
SUBSTANCE: fish roe is homogenised. Fish roe hydrolysis is carried out with a ferment preparation "Collagenase" in presence of an inhibitor for 10-12 hours. Chitosan is added to the produced hydrolysate at the ratio of 0.5-1.0:1.0. Components are mixed.
EFFECT: invention makes it possible to accelerate process of chitosan-nucleic complex production.
1 dwg, 1 tbl, 3 ex
SUBSTANCE: method includes depolymerisation of a high-molecular chitosan with hydrogen peroxide. The process of chitosan depolymerisation is carried out in a double-phase system. The solid phase is activated chitosan with Mav = 450-650 kDa and the average particle size of 0.05-0.20 mm. The liquid phase is a water solution of H2O2 with concentration of H2O2 in a reaction system equal to 1-7%. The reaction is carried out for 120-180 minutes at 70°C. Then phase separation of produced chitosan homologs is carried out by means of filtration via paper or textile surface of the produced reaction mixture. The produced filtrate contains water-soluble chitosan oligomers.
EFFECT: invention makes it possible to quantitatively control extent of conversion of an initial high-molecular chitosam into oligomer and low-molecular structures of its homologs.
1 tbl, 1 ex
SUBSTANCE: invention relates to a method of purifying chondroitin sulphate and can be used in food and cosmetic industry and in medicine. The method involves electrochemical deposition to obtain a hydrogel of chondroitin sulphate, stabilisation, removal from the electrode, washing and drying. The chondroitin sulphate is dissolved in a 0.01-0.1 n alkali solution in ratio of 1:50-1:200 and deposited in an alkaline medium with constant cooling and stirring. The solution is stirred at a rate of 10-20 rpm. Current density is equal to 1-10 A/m2. Voltage is preferably not lower than 2.7 V. The hydrogel of chondroitin sulphate is stabilised in a 0.05-0.5 n HCl solution.
EFFECT: invention enables to obtain chondroitin sulphate with high weight ratio of the basic substance and increases output of the end product.
5 cl, 1 ex
SUBSTANCE: present invention relates to a method of producing a N,S-cyclo-containing chitosan derivative. Described is a method of producing a chitosan-based N,S-cyclo-containing polymer (I) which contains in the macrochain 1-oxa-6-thia-4,8-diazocycloundecane fragments: I, by reacting chitosan with formaldehyde and a S-containing compound, characterised by that the S-containing compound used is hydrogen sulphide, the formaldehyde solution is pre-saturated with H2S and the reaction is carried out with molar ratio chitosan: formaldehyde: hydrogen sulphide of 1:2:1, at temperature of 0-60°C in a chloride medium for 24 hours.
EFFECT: obtaining modified chitosan which exhibits properties of a highly efficient heavy metal sorbent for waste water treatment, an extractant for separating rare, noble and precious metals and a complexing agent for biological molecules.
1 tbl, 3 ex
FIELD: medicine, pharmaceutics.
SUBSTANCE: invention refers to biochemistry. What is presented is a conjugate of hyaluronic acid and novocaine of a structure as defined in the patent claim containing 20-50% residues of novocaine.
EFFECT: conjugate is water-soluble; it possess the amphoteric properties and contains no side O-acylisourea.
3 tbl, 3 ex
FIELD: fish industry.
SUBSTANCE: method involves providing deacetylation of raw material with the use of preliminarily cooled alkaline solution; washing and drying. Deacetylation process is performed in three stages, first stage being performed for 7 days and subsequent two stages being performed for 2 hours each, combined with thermal processing at temperature of 55-590C. Washing process is provided after each deacetylation stage.
EFFECT: provision for producing of chitosan from chitin of cancerous with increased extent of deacetylation, while native properties of natural polymer being kept, without breaking of glycoside binding chain.
FIELD: organic chemistry.
SUBSTANCE: claimed method includes subsequent chitosane-containing raw material with non-polar liquefied gas, water, alkali, water, acid, water, alkali, and water to produce target product in form of solid residue, wherein in at least first extraction step pressure in reaction mixture is periodically released to provide extractant boiling, and than increased up to starting value.
EFFECT: method with reduced energy consumption.
FIELD: chemical technology of natural compounds.
SUBSTANCE: invention describes a method for preparing water-soluble derivatives of chitosan. Method involves treatment of chitosan with acid medium up to its swelling wherein vapor medium water-acid is used as acid medium. Treatment of chitosan is carried out with vapor of monobasic acid aqueous solution taken among the group including hydrochloric acid, formic acid and acetic acid. Method allows simplifying technology in preparing water-soluble derivatives of chitosan.
EFFECT: improved preparing method.
4 cl, 1 tbl, 9 ex
FIELD: chemistry and technology of derivatives of polysaccharides, chemical technology.
SUBSTANCE: invention relates to methods for preparing chitosan esters. Invention describes a method for preparing chitosan polyethylene glycol ester that involves dissolving chitosan in acetic acid followed by alkalization. Then the reaction mixture is subjected for effect of ethylene oxide under pressure 1-3 atm and temperature 60-100°C, and the concentration of reaction mass is corrected by addition of distilled water up to the density value of solution 1.030-1.032 g/cm3. Then the reaction mass is purified by electrodialysis at the rate value of solution in treatment chambers 3.0 cm/s, not less, temperature 20-45°C, the current density value 0.25-0.75 A/dm2 and the constant volume of the reaction mass. Method provides enhancing the effectiveness of purification by electrodialysis due to reducing energy consumptions. Chitosan esters can be used in medicine, cosmetics, food and chemical industry.
EFFECT: improved preparing method.
FIELD: organic chemistry of natural compounds, chemical technology, medicine.
SUBSTANCE: invention relates to the group of chitosan-containing compounds. Invention relates to synthesis of modified chitosan of the following structure: wherein n = 150-1400. The modified chitosan possesses the bactericidal activity, in particular, antituberculosis activity.
EFFECT: valuable medicinal properties of modified chitosan.
1 tbl, 1 dwg, 3 ex
FIELD: natural compounds technology.
SUBSTANCE: chitosan preparation process comprises breaking naturally occurring chitin-containing material, charging it into reactor, demineralization with 6-7% aqueous hydrochloric acid, deproteination with sodium hydroxide solution at 85-95°C, deacetylation with sodium hydroxide solution on heating, decoloration, and washing with water after each stage to pH 6.5. Process is characterized by that chitin-containing material broken to achieve fraction 0.5-6 mm is fed simultaneously into a number of reactors, wherein demineralization is effected with aqueous hydrochloric acid stream at 85-95°C for 1.5 h while controlling pH in each reactor exit to achieve acid concentration in each reactor exit the same as concentration of the initial acid by way of feeding it in a continuous manner. In addition, deproteination is carried out with 6-7% sodium hydroxide solution stream for 1.5 h followed by discharging treated material into autoclave to perform deacetylation simultaneously with decoloration using 50% sodium hydroxide solution at 130-140°C in inert gas environment and in presence of 3-5% hydrogen peroxide solution used in amount 3-5% of the total volume of mixture.
EFFECT: enhanced process efficiency.
FIELD: chemical technology.
SUBSTANCE: invention relates to methods for preparing water-soluble saline complexes (associates) of hyaluronic acid with d-metals of IV, V and VI periods of Mendeleyev's periodic system of elements that can be used in pharmacology and cosmetology. Invention describes a method for preparing water-soluble saline complexes of hyaluronic acid involving preparing an aqueous solution of salt of d-metal of IV, V and VI periods of periodic system and its mixing with hyaluronic acid sodium salt, holding the mixture, its stirring, dilution with water and isolation of the end product. For mixing method involves using the amount of aqueous salt of abovementioned d-metal that is equivalent to the amount of carboxy-groups of hyaluronic acid sodium salt or in the limit from 0.95 to 1.10. After dilution with water the solution mixture is subjected for ultrafiltration on separating membranes with simultaneous washing out with aqueous salt solution of abovementioned d-metal firstly and then with deionized water followed by concentrating the product. By another variant for mixing the method involves the amount of aqueous solution of d-metal salt lesser of the equivalent amount of carboxy-groups in hyaluronic acid sodium salt. After dilution with water the mixture is subjected for ultrafiltration on separating membranes with simultaneous washing out with deionized water followed by concentrating the product also. Method is characterized by the decreased time of processes and simplicity.
EFFECT: improved preparing method.
2 cl, 1 tbl
FIELD: medicine, food processing industry, in particular production of depolymerized chitosane and products based on the same.
SUBSTANCE: claimed method is based on using of chitosanase in acetic acid medium and spray drying of and depolymerized chitosane and is characterized in that obtained depolymerized chitosane is preliminary converted in non-ionized form by neutralizing of bound acetic acid with ammonium hydroxide followed by precipitation in ethanol and air drying. Further interaction is carried out with ammonium lipoate or glutathione in aqueous medium. Claimed products may be used individually or in combination with other components.
EFFECT: new products for food processing industry and medicine.
4 cl, 2 ex
FIELD: organic chemistry, chemical technology.
SUBSTANCE: invention relates to a method for preparing modified glycosaminoglycans possessing analgesic properties. Method involves interaction of glycosaminoglycans with 1-phenyl-2,3-dimethyl-4-aminopyrazolone-5-(4-aminoantipyrine) in aqueous medium at pH = 4.7-4.8 in the presence water-soluble 1-ethyl-3-[3-(dimethlamino)propyl]carbodiimide as a condensing agent at room temperature followed by purification from low-molecular reagents. Method involves a single step that simplifies technology in preparing modified glycosaminoglycans.
EFFECT: improved preparing method.
FIELD: natural substances, chemical technology.
SUBSTANCE: invention relates to a method for preparing chitosan and purification from components of the reaction mixture - low-molecular products of deacetylation and alkali excess. Invention relates to a method for purifying chitosan prepared by solid-state method involving treatment of reaction mass with extractant consisting of 3.3-20.0% of water, 32.2-57.1% of ethyl acetate and 24.6-64.5% of ethanol at the extractant boiling point. Also, invention relates to a method for purifying chitosan prepared by suspension method and involving treatment of the reaction mass with ethyl acetate and the following treatment with extractant consisting of 6.2-25.0% of water, 12.5-62.5% of ethyl acetate and 31.3-62.5% of ethanol at the extractant boiling point.
EFFECT: improved isolating and preparing method.
3 cl, 2 tbl, 1 dwg