RU2523545C1 - Method of obtaining betulin (versions) - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to versions of a method of obtaining betulin from bark of birch, including the bark crushing, its separation into the birch bark and bast, extraction of the birch bark with toluol, exposure to microwave radiation for 20 minutes at a temperature of the mixture boiling or at a temperature of 150°C under pressure 0.28 MPa; the solution is filtered at a temperature of 60÷70°C, a betulin solution in toluol is evaporated, betulin crystals are washed with ethyl or isopropyl alcohol, water and dried.

EFFECT: intensification of the technological process of betulin obtaining with an increase of the output and improvement of the target product quality.

2 cl, 2 ex

Description

The present invention relates to methods for extracting valuable chemical products from waste wood processing, and in particular to a method for producing betulin from birch bark, used in the medical, alcoholic beverage and perfume industries.

A known method of producing betulin from birch birch bark, including crushing the bark, separation of the bark into bark and bast, extraction of birch bark with alcohol, separation of the solution, followed by removal of the solvent from it. The extraction is carried out with 90 ÷ 95% ethyl alcohol at a temperature of 70 ÷ 75 ° C for 3 hours, while activated carbon is added during the extraction [RF Patent No. 2172178, cl. A61K 35/78, C08H 5/04, 2001].

The disadvantage of this method is the duration of the operation for extracting betulin from birch bark, as well as the need to add activated carbon mass fraction of 35 ÷ 45% by weight of absolutely dry birch bark.

A known method of producing betulin from birch birch bark, including its activation at a temperature of 180 ÷ 260 ° C, a pressure of 2 ÷ 5 MPa for 60 ÷ 300 s, alkali treatment and extraction with alcohol [RF Patent No. 2131882, cl. C07J 53/00, C07J 63/00, 1998].

The disadvantage of this method is the complex activation process of birch bark, which requires the use of high pressure and high temperature to produce superheated water vapor, which complicates the technology and increases the energy intensity of the betulin production process.

The closest in technical essence method is the extraction of birch bark with a mixture of solvents containing petroleum ether (PE) with boiling limits of 70 ÷ 100 ° C and 30 ÷ 75% toluene, while the yield of the extract is from 16 to 25% of absolutely dry matter, and the content betulin from 90 to 95% [RF Patent No. 2184120, cl. C07J 53/00, C07J 63/00, 2002 (prototype)].

In the known method, the extraction of birch bark is carried out with a mixture of solvents containing petroleum ether and toluene for three hours. For extraction, the outer layer of birch bark Betula Pendula Roth was taken. Birch bark was pre-crushed to a particle size of 20 × 5 × 0.1 mm. A mixture of petroleum ether (fraction 70-100 ° C) with toluene 1: 1 by volume (100 ml) was used as an extractant. The resulting extract was evaporated on a vacuum evaporator and dried at a temperature of 40 ° C over calcium chloride CaCl ₂ . When extracted with a mixture of PE with toluene, betulin does not crystallize, but precipitates. 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 disadvantages of this method is the duration of betulin production, low yield and purity of the product, due to this low process efficiency.

An object of the invention is the intensification of the process for producing betulin, increasing the efficiency of its extraction while improving the quality of the target product. Sagging birch (Betula pendula) was taken as an object for extraction.

The problem is solved in the following way: a method of producing betulin from a birch bark involves crushing the bark, separating it into birch bark and bast, extracting birch bark with toluene, separating the solution and then removing the solvent from it, according to the invention, the crushed birch bark with toluene is exposed to microwave radiation for 20 minutes at the boiling temperature of the mixture, after which the reaction mixture is filtered at a temperature of 60 ÷ 70 ° C, then the filtrate containing a solution of betulin in toluene is evaporated, betulin crystals washed with ethyl or isopropyl alcohol, then with water and dried. The yield of the target product is 28%, the obtained dry powder is 97% pure betulin (powder from white to cream color).

In the second embodiment, the task is solved as follows: the method of producing betulin from birch bark involves crushing the bark, separating it into birch bark and bast, extracting birch bark with toluene, separating the solution and then removing the solvent from it, according to the invention, the crushed birch bark with toluene is exposed to microwave radiation for 20 minutes at a temperature of 150 ° C under a pressure of 0.28 MPa, after which the reaction mixture is filtered at a temperature of 60 ÷ 70 ° C. Then toluene is evaporated from the betulin solution, the betulin crystals are washed with ethyl or isopropyl alcohol, then with water and dried. The yield of the target product is 33% by weight of dry birch bark, the obtained dry powder is betulin 97% pure (powder from white to cream color). Methods for producing betulin from birch bark are illustrated by examples.

Example 1. The birch bark is crushed on a grinder and the crushed bark is divided into birch bark and bast. Extraction of birch bark with toluene is carried out in a 0.5 l reactor. The mass of birch bark is not more than 0.05 kg. Toluene is loaded in an amount of not more than 0.15 kg.

The mixture is exposed to microwave radiation for 20 minutes at a boiling point of 100 ÷ 110 ° C. After completion of the extraction process, the reaction mixture is filtered at a temperature of 60 ÷ 70 ° C. The filter element is filter-calico or belting fabric. After filtration was completed, toluene was evaporated. The distilled toluene enters the regeneration. A vacuum is used to increase the speed of distillation of toluene. To obtain a cleaner product, betulin crystals are washed with ethyl or isopropyl alcohol, then with water and dried. The yield of the target product is 28% by weight of dry bark, the resulting powder is white to cream in color weighing 14 grams and is betulin 97% pure.

Example 2. The birch bark is crushed on a grinder and the crushed bark is divided into birch bark and bast. Extraction of birch bark with toluene is carried out in a 0.5 l reactor. The mixture is exposed to microwave radiation for 20 minutes at a temperature of 150 ° C under a pressure of 0.28 MPa. After completion of the extraction process, the reaction mixture is filtered at a temperature of 60 ÷ 70 ° C. The filter element is filter-calico or belting fabric. After filtration is complete, toluene is distilled off from betulin solution. The distilled toluene enters the regeneration. A vacuum is used to increase the speed of distillation of toluene. Betulin crystals are cleaned from the walls and bottom, to obtain a cleaner product, the crystals are washed with ethyl or isopropyl alcohol, then washed with water and dried. The extract yield is 33% by weight of dry birch bark, the resulting powder is white to cream in color and is 97% pure betulin, weighing 16.5 grams.

Betulin according to the proposed methods is obtained with a yield of up to 35% by weight of dry birch bark in 20 minutes, while the production of betulin, in a known manner with a yield of up to 25%, takes from 1.5 to 3.0 hours for the extraction and cooling of betulin in toluene within 6 ÷ 10 hours to a temperature of 15 ÷ 5 ° C. In our proposed method, betulin is obtained in high quality in the form of a powder from white to cream color with a betulin content of 97% purity.

The proposed methods are simple and technologically advanced, all operations are easily feasible, concentrated acids and alkalis are not used. The resulting product is a triterpene dihydric alcohol - pharmacopoeial betulin and is a valuable raw material for the distillery, pharmaceutical and perfume industries.

Claims (2)

1. A method of producing betulin from birch bark, including crushing the bark, separating it into birch bark and bast, extracting birch bark with toluene, separating the solution, followed by removing solvent from it, characterized in that the crushed birch bark with toluene is exposed to microwave radiation for 20 minutes at the boiling temperature of the mixture, filter the solution at a temperature of 60 ÷ 70 ° C, evaporate the solution of betulin in toluene, wash the crystals of betulin with ethyl or isopropyl alcohol, water and dry. 2. A method of producing betulin from birch bark, including crushing the bark, dividing it into birch bark and bast, extracting birch bark with toluene, separating the solution, followed by removing the solvent from it, characterized in that the crushed birch bark with toluene is exposed to microwave radiation for 20 minutes at temperature of 150 ° C under a pressure of 0.28 MPa, filter the solution at a temperature of 60 ÷ 70 ° C, evaporate the solution of betulin in toluene, the crystals of betulin are washed with ethyl alcohol or isopropyl alcohol, then with water and dried.