RU2184120C1 - Method of betulin preparing - Google Patents

Abstract

FIELD: chemical technology of natural substances. SUBSTANCE: invention relates to a method of production of betulin from a birch external layer bark. Method is carried out by extraction of betulin from the birch ground bark with a mixture of solvents containing petroleum ether at 70-100 C with addition of toluene taken in the amount 30-75% of the total extractant volume followed by crystallization of betulin. The yield of extract is 16-25% of absolutely dry matter in a content of betulin 90-95%. EFFECT: improved method of betulin extraction. 1 tbl, 1 dwg

Description

 The invention relates to the field of chemistry and can be used for processing birch bark - the outer layer of the birch bark.

 Large pulp and paper and wood processing enterprises accumulate a large amount of bark annually as a result of the inevitable debarking of birch wood. Birch bark is a valuable raw material for the production of new biologically active substances. The main content of birch bark extractives is betulin. Betulin is isolated by extraction with organic solvents and subsequent recrystallization. Betulin is used to treat a number of diseases, and it is also a cheap starting compound for the synthesis of other biologically active substances.

A known method of producing betulin (RF Patent 2074867, C 07 J 53/00, 63/00, 1992.06.16). The essence of the method lies in the fact that betulin is obtained from birch birch, previously activated in non-isobaric steam cracking conditions with the following parameters: pressure 2-5 MPa, temperature 180-260 ^o C, holding time 60-360 s.

A known method of producing betulin (RF Patent 2131882, C 07 J 53/00, 63/00, 1998.03.26). The method includes activation of birch birch at a pressure of 2-5 MPa, a temperature of 180-260 ^o C, a holding time of 50-360 s, alkali treatment and extraction with alcohol, while the activation of birch birch and its alkaline hydrolysis are carried out simultaneously, and alkali is taken in an amount of 10 -20% by weight of absolutely dry birch bark.

 The disadvantage of the above methods for producing betulin is the relatively low yield of pure product.

 The problem to which the invention is directed, is to increase the yield and increase the purity of betulin.

 The problem is solved as follows.

The method of producing betulin is based on the extraction of betulin from the birch bark using an extractant and subsequent crystallization and is characterized in that a solvent mixture containing petroleum ether of 70-100 ^° C and 30-75% toluene is used as extractant, and the extract has a yield of 16 up to 25% of absolutely dry matter, and the content of betulin in the sediment from 90 to 95%.

 The proposed method is illustrated in the drawing, which shows the technological scheme for producing betulin.

Betulin is isolated from birch bark by extraction with organic solvents and subsequent recrystallization. When used as extractant hydrocarbon solvents with a boiling point of 150-185 ^o With the mass fraction of betulin and the yield of extractives are at a high level.

For extraction, the outer layer of the birch bark Betula Pendula Roth is taken. Humidity of birch bark (%) of absolutely dry raw materials is not more than 5%. A solvent mixture containing petroleum ether 70-100 ^o C (PE) and 30-75% toluene is used as an extractant.

 The technological process of extraction is as follows.

 The crushed birch bark is loaded into the extractor 1, where the solvent is fed from the collector 2 by the pump 3, which is heated in the heater 4. The solvent vapor condenses in the refrigerator 5. The extraction takes 5 hours. After extraction, the hot extract is poured into crystallizer 6. The residual solvent from the bark is distilled off with hot steam, the solvent is separated in Florentine 7 and enters the collection 2. The crystallizer is equipped with a stirrer and a cooling jacket. After cooling, the extract is fed to a vacuum suction filter 8. The filtrate through an intermediate receiver 9 is evaporated into the evaporator 10. The solvent is removed from the precipitate with hot steam.

When using as a extractant a mixture containing petroleum ether 70-100 ^o C and 30-75% toluene, the extract yield is from 16 to 25% of absolutely dry matter, and the content of betulin in the sediment from 90 to 95%.

 EXAMPLE 1

To isolate betulin from birch birch, the method of extraction of bark in Soxhlet was chosen. The extraction was carried out for three hours. For extraction, the outer layer of birch bark Betula Pendula Roth was taken. Birch bark (weight 170 g) was pre-crushed to a particle size of 20x5x0.1 mm. The moisture content of the birch bark is 4.4% (determined by drying the sample at a temperature of 105 ^o C). As an extractant, a mixture of petroleum ether 70-100 ^o With 50% toluene in a ratio of 1: 1 (volume 100 ml) was used. The resulting extract was evaporated on a vacuum evaporator and dried at an initial temperature of 40 ^{° C.} over calcium chloride CaCl ₂ .

When extracted with a mixture of PE with toluene in a ratio of 1: 1, betulin does not crystallize, but precipitates upon cooling and is easily filtered off. The yield of the extract is 19.6% of absolutely dry matter. Column chromatography showed that the content of betulin in the precipitate was 93%. The content of lupeol, which is the main impurity in the extract, is 5%. Yield 33.3 g. Mp. 257-259 ^o C.

 EXAMPLE 2

 Getting betulin produce the same way as in example 1.

A mixture of petroleum ether 70-100 ^o With 30% toluene was used as extractant.

The extract yield is 16.0% of absolutely dry matter. The betulin content in the sediment is 91%. The content of lupeol, which is the main impurity in the extract, is 6%. Betulin yield 27.2 g. Appearance - cream-colored powder, no mechanical impurities. Mp 252-254 ^o C.

 The proposed method will find application for producing betulin in the processing of large-tonnage waste obtained by processing birch.

Claims (1)

A method of producing betulin by extracting betulin from birch bark using an extractant followed by crystallization, characterized in that a solvent mixture containing petroleum ether 70-100 ^{° C.} with toluene from 30 to 75% of the total extractant volume is used as extractant.

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