Patent CN102399205A discloses a method for purifying mycophenolic acid: dissolving the crude mycophenolic acid into 18-22 times (v/w) methanol at 50-90 ℃, adding active carbon with the mass of 6-10% of that of the crude mycophenolic acid for decoloring, filtering, concentrating and crystallizing to obtain a pure mycophenolic acid product with the purity of more than 99%. The purification method uses a large amount of solvent.

CN103880798A discloses a method for purifying mycophenolic acid. The method comprises the following steps: 1) providing an ethanol solution of mycophenolic acid at a temperature of 50 ℃ to 70 ℃; 2) cooling the ethanol solution obtained in the step 1) to 10-30 ℃ to separate out mycophenolic acid crystals, and separating to obtain mycophenolic acid crystals; 3) dissolving the mycophenolic acid crystals obtained in the step 2) with ethanol, mixing the obtained solution with water at the temperature of 5-12 ℃, recrystallizing and separating mycophenolic acid, and separating to obtain mycophenolic acid recrystallized crystals. The method uses large amount of solvent and purified water, and obtains pure amorphous mycophenolic acid.

The literature "development of novel immunosuppressive agents, mycophenolic acid and mycophenolate mofetil" (university of Zhejiang, Master academic thesis, happy god, 2006) discloses another method for purifying mycophenolic acid: adding 7-10% of diatomite into the fermentation liquor, stirring for 30min, and filtering to obtain thalli; soaking thallus in ethanol, filtering to obtain soaking solution, concentrating to dryness to obtain mycophenolic acid solid, dissolving the mycophenolic acid solid in 2 times volume of ethyl acetate, adding 5% active carbon, stirring for decolorizing, filtering, concentrating, standing for crystallization, filtering to obtain mycophenolic acid crude product, dissolving the crude product in 5 times volume of ethanol at 40 ℃, standing for 24h at-4 ℃, filtering, and drying to obtain mycophenolic acid pure product with the content of 99%. The yield thereof was found to be about 45%. The process needs refrigeration, temperature reduction and crystallization, has large energy consumption in industrial production, is difficult to implement, uses various solvents and increases the recovery difficulty.

Disclosure of Invention

In the process of purifying mycophenolic acid, impurity A is found to be difficult to remove, and the structure of the impurity A is deduced to be shown in (III) through detailed research:

in order to solve the problems in the prior art and remove the impurity A, the invention provides a method for purifying mycophenolic acid. The purification method comprises the following steps:

1) adding mycophenolic acid into a mixed solution of acetone and hydrochloric acid, heating, stirring and dissolving; the heating temperature is above 40 ℃;

2) adding active carbon, stirring and decoloring;

3) filtering;

4) dropwise adding a solvent B into the filtrate;

5) cooling and crystallizing;

6) filtering, washing and drying to obtain the pure mycophenolic acid.

In the step 1), the volume ratio of acetone to hydrochloric acid in the mixed solution is (7-10): 1; the proportion of the mycophenolic acid crude product to the acetone-hydrochloric acid mixed solution is 1 (5-9) (w/v); preferably, the volume ratio of the acetone to the hydrochloric acid in the mixed solution is (8-10) to 1; preferably, the proportion of the mycophenolic acid crude product to the acetone-hydrochloric acid mixed solution is 1 (6-9) (w/v); preferably, the dissolving temperature is controlled to be 45-55 ℃; preferably, the concentration of the hydrochloric acid is 0.1-3M (the mass concentration of the substance is 0.1-3 mol/L);

in the step 2), the amount of the added active carbon is about 3-5% (mass percentage) of the crude mycophenolic acid; furthermore, the amount of the added active carbon is 5 percent (mass percentage) of the crude mycophenolic acid.

In the step 4), the solvent B is one or more of petroleum ether, n-hexane and heptane, and the ratio of the dosage of the solvent B to the mycophenolic acid crude product is (5-10): 1 (v/w); preferably, the ratio of the dosage of the solvent B to the crude mycophenolic acid is (8-10): 1 (v/w);

in the step 5), the temperature of heat preservation and crystallization is controlled to be 15-35 ℃; preferably, the temperature of heat preservation and crystallization is controlled between 15 and 30 ℃.

Compared with the prior art, the method of the invention has the following advantages and positive effects:

1. the invention uses the mixed solvent, better realizes the purification purpose of the mycophenolic acid, ensures that the purity of the mycophenolic acid pure product is higher than 99.6 percent, and the impurity A is less than 0.05 percent; the yield is higher than 85%. ' Qiyi

2. The invention does not need to carry out freezing and temperature reduction in the crystallization and recrystallization processes, thereby reducing the energy consumption.

3. The method has simple process, safety and low cost, and is suitable for large-scale industrial production.

Detailed Description

The present invention is further illustrated by the description of the specific embodiments, but the present invention is not limited thereto, and those skilled in the art can make various modifications or improvements based on the basic idea of the present invention within the scope of the present invention as long as they do not depart from the basic idea of the present invention.

Example 1

Adding 540ml of acetone and 60ml of 1M hydrochloric acid into 100g of the mycophenolic acid crude product, stirring and heating to 45 ℃, adding 5g of activated carbon after dissolving, keeping the temperature and stirring for 30 minutes, and filtering; under stirring, dripping 800ml of normal hexane into the filtrate at 30 ℃ until dripping is finished; keeping the temperature at 15 ℃, stirring and crystallizing for 2.5 hours, filtering, pulping and washing a filter cake by 50ml of purified water; vacuum drying at 40 deg.C to obtain 87.6g pure product with purity of 99.68% and impurity A of 0.017%.

The following HPLC analysis conditions were used for the detection of mycophenolic acid:

agilent 110 high performance liquid chromatograph

Reagent potassium dihydrogen phosphate, concentrated phosphoric acid, purified water, methanol and acetonitrile

Sample size of 10 μ L

Chromatographic column Agilent XDB-C84.6mm X15 cm chromatographic column

Flow rate 1.5ml/min

Column temperature 45 deg.C

Detection wavelength of 250nm

Mobile phase PH 3.0 phosphate buffer: acetonitrile: methanol 60: 35: 11

Diluent acetonitrile

The method for detecting mycophenolic acid in the present invention is not particularly limited, and mycophenolic acid can be detected by the method.

Example 2

Adding 550ml of acetone and 55ml of 0.5M hydrochloric acid into 100g of the crude mycophenolic acid, stirring and heating to 55 ℃, adding 5g of activated carbon after dissolving, keeping the temperature and stirring for 30 minutes, and filtering; under stirring, dropwise adding 800ml of petroleum ether into the filtrate at 30 ℃, and finishing dripping; keeping the temperature at 20 ℃, stirring, crystallizing for 3 hours, filtering, pulping and washing a filter cake by 50ml of purified water; vacuum drying at 40 deg.C to obtain 86.2g pure product with purity of 99.63% and impurity A of 0.022%.

Example 3

Adding 100g of mycophenolic acid crude product into 800ml of acetone and 100ml of 0.5M hydrochloric acid, stirring and heating to 45 ℃, adding 5g of activated carbon after dissolving, keeping the temperature and stirring for 30 minutes, and filtering; under stirring, dripping 800ml of petroleum ether into the filtrate at 35 ℃ until dripping is finished; keeping the temperature at 25 ℃, stirring and crystallizing for 3 hours, filtering, and pulping and washing a filter cake by 50ml of purified water; vacuum drying at 40 deg.C to obtain 85.6g pure product with purity of 99.74% and impurity A of 0.028%.

Example 4

Adding 100g of mycophenolic acid crude product into 800ml of acetone and 100ml of 0.5M hydrochloric acid, stirring and heating to 45 ℃, adding 5g of activated carbon after dissolving, keeping the temperature and stirring for 30 minutes, and filtering; under stirring, dripping 1000ml of normal hexane into the filtrate at 35 ℃ until dripping is finished; keeping the temperature at 15 ℃, stirring and crystallizing for 2.5 hours, filtering, pulping and washing a filter cake by 50ml of purified water; vacuum drying at 40 deg.C to obtain 88.1g pure product with purity of 99.62% and impurity A of 0.017%.

Example 5

Adding 100g of mycophenolic acid crude product into 800ml of acetone and 80ml of 2M hydrochloric acid, stirring and heating to 45 ℃, adding 5g of activated carbon after dissolving, keeping the temperature and stirring for 30 minutes, and filtering; under stirring, dripping 500ml of mixed solution of n-hexane and heptane (volume ratio 1:1) into the filtrate at 35 deg.C, and finishing dripping; keeping the temperature at 15 ℃, stirring and crystallizing for 2.5 hours, filtering, pulping and washing a filter cake by 50ml of purified water; vacuum drying at 40 deg.C to obtain 88.3g pure product with purity of 99.68% and impurity A of 0.025%.

Example 6

Adding 100g of mycophenolic acid crude product into 800ml of acetone and 100ml of 2M hydrochloric acid, stirring and heating to 45 ℃, adding 5g of activated carbon after dissolving, keeping the temperature and stirring for 30 minutes, and filtering; under stirring, dripping 800ml of petroleum ether into the filtrate at 35 ℃ until dripping is finished; keeping the temperature at 25 ℃, stirring and crystallizing for 3 hours, filtering, and pulping and washing a filter cake by 50ml of purified water; vacuum drying at 40 deg.C to obtain 87.6g pure product with purity of 99.79% and impurity A of 0.031%.

Example 7

Adding 100g of mycophenolic acid crude product into 800ml of acetone and 100ml of 0.5M hydrochloric acid, stirring and heating to 45 ℃, adding 5g of activated carbon after dissolving, keeping the temperature and stirring for 30 minutes, and filtering; cooling the filtrate to 15 ℃ under stirring, preserving heat, stirring, crystallizing for 3 hours, filtering, and pulping and washing a filter cake by using 50ml of purified water; vacuum drying at 40 deg.C to obtain 45.7g pure product with purity of 94.79% and impurity A of 0.069%.

Example 8

Adding 100g of mycophenolic acid crude product into 550ml of ethanol and 50ml of 0.5M hydrochloric acid, stirring and heating to 55 ℃, adding 5g of activated carbon after dissolving, keeping the temperature and stirring for 30 minutes, and filtering; under stirring, dropwise adding 800ml of ethyl acetate into the filtrate at 30 ℃, and finishing the dropwise adding; keeping the temperature at 20 ℃, stirring, crystallizing for 3 hours, filtering, pulping and washing a filter cake by 50ml of purified water; vacuum drying at 40 deg.C to obtain 66.2g pure product with purity of 95.93% and impurity A of 0.091%.

Example 9

Adding 540ml of acetone and 60ml of purified water into 100g of the crude mycophenolic acid, stirring and heating to 45 ℃, adding 5g of activated carbon after dissolving, keeping the temperature and stirring for 30 minutes, and filtering; under stirring, dripping 800ml of normal hexane into the filtrate at 30 ℃ until dripping is finished; keeping the temperature at 15 ℃, stirring and crystallizing for 2.5 hours, filtering, pulping and washing a filter cake by 50ml of purified water; vacuum drying at 40 deg.C to obtain 75.6g pure product with purity of 96.08% and impurity A of 0.087%.

Example 10

Adding 100g of mycophenolic acid crude product into 550ml of ethanol and 50ml of 0.5M hydrochloric acid, stirring and heating to 55 ℃, adding 5g of activated carbon after dissolving, keeping the temperature and stirring for 30 minutes, and filtering; under stirring, dropwise adding 800ml of petroleum ether into the filtrate at 30 ℃, and finishing dripping; keeping the temperature at 20 ℃, stirring, crystallizing for 3 hours, filtering, pulping and washing a filter cake by 50ml of purified water; vacuum drying at 40 deg.C gave 73.9g of pure product with a purity of 94.19% and 0.121% of impurity A.

Example 11

Adding 540ml of acetone and 60ml of 1M phosphoric acid into 100g of the mycophenolic acid crude product, stirring and heating to 45 ℃, adding 5g of activated carbon after dissolving, keeping the temperature and stirring for 30 minutes, and filtering; under stirring, dripping 800ml of normal hexane into the filtrate at 30 ℃ until dripping is finished; keeping the temperature at 15 ℃, stirring and crystallizing for 2.5 hours, filtering, pulping and washing a filter cake by 50ml of purified water; vacuum drying at 40 deg.C to obtain 71.2g pure product with purity of 95.69% and impurity A of 0.103%.

Claims

1. A method for purifying mycophenolic acid, comprising the steps of:

2) adding active carbon, stirring and decoloring;

3) filtering;

4) dropwise adding a solvent B into the filtrate;

5) cooling and crystallizing;

6) filtering, washing and drying to obtain a pure mycophenolic acid product;

in the step 1), the volume ratio of acetone to hydrochloric acid in the mixed solution is 7-10: 1; the proportion of the mycophenolic acid crude product to the acetone-hydrochloric acid mixed solution is w/v =1: 5-9;

in the step 4), the solvent B is one or more of petroleum ether, n-hexane and heptane, and the ratio of the dosage of the solvent B to the mycophenolic acid crude product is v/w = 5-10: 1;

in step 5), the temperature for crystallization is controlled to be 35 ℃ or lower.

2. The method for purifying mycophenolic acid as claimed in claim 1, wherein in step 1), the dissolution temperature is controlled at 45-55 ℃.

3. The method for purifying mycophenolic acid as claimed in claim 1, wherein in the step 1), the volume ratio of acetone to hydrochloric acid in the mixed solution is 8-10: 1.

4. The method for purifying mycophenolic acid as claimed in claim 1, wherein in the step 1), the ratio of the mycophenolic acid crude product to the acetone-hydrochloric acid mixed solution is w/v =1: 6-9.

5. The method for purifying mycophenolic acid as claimed in claim 1, wherein in the step 1), the concentration of the hydrochloric acid is 0.1-3M.

6. The method for purifying mycophenolic acid as claimed in claim 1, wherein in the step 2), the amount of the added activated carbon is 3-5% of the crude mycophenolic acid in percentage by mass.

7. The method for purifying mycophenolic acid as claimed in claim 1, wherein in step 2), the amount of the added activated carbon is 5% of the crude mycophenolic acid in mass percent.

8. The method for purifying mycophenolic acid as claimed in claim 1, wherein in the step 4), the solvent B is one or two of n-hexane and heptane.

9. The method for purifying mycophenolic acid as claimed in claim 1, wherein in the step 4), the ratio of the amount of the dropwise added solvent B to the amount of the crude mycophenolic acid is v/w = 8-10: 1.

10. The method for purifying mycophenolic acid as claimed in any one of claims 1 to 9, wherein in the step 5), the temperature for thermal crystallization is controlled to be 15 ℃ to 30 ℃.