Green preparation method for purifying oxytetracycline hydrochloride based on multi-stage filter membrane

Abstract

The invention discloses a green preparation method for purifying oxytetracycline hydrochloride based on multistage filter membranes, and belongs to the technical field of antibiotic preparation. The preparation method comprises the following steps: adding anhydrous calcium chloride and oxytetracycline into methanol, stirring and dissolving; filtering the mixed solution through a filter membrane, cooling the filtrate, and adding an acid alcohol solution to adjust the pH value for acidification; carrying out two-stage filtration on the obtained acidizing fluid through a filter membrane, and cooling the filtrate until the filtrate is crystallized; and finally, washing the filtrate with frozen methanol, and drying to obtain oxytetracycline hydrochloride. According to the method, through the physical screening effect of the PTFE filter membrane, impurities and endotoxin aggregates with different particle sizes are directly intercepted, and efficient purification, environmental protection and emission reduction are achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of antibiotic preparation, and in particular relates to a green preparation method of oxytetracycline hydrochloride based on multi-stage filtration membrane purification. Background Art

[0002] Oxytetracycline hydrochloride, chemical name is 6-methyl-4-(dimethylamino)-3,5,10,12,12a-hexahydroxy-1,11-dioxo-1,4,4a,5,5a,6,11,12a-octahydro-2-naphthacenecarboxamide hydrochloride, the structural formula is:

[0003]

[0004] In the traditional preparation process of oxytetracycline hydrochloride, activated carbon adsorption, multiple recrystallizations or ion exchange chromatography are often used to remove impurities and endotoxins, which have the following defects:

[0005] 1) High solid waste emissions: solid-liquid separation is required after activated carbon adsorption, and waste gas adsorbents and by-products lead to increased solid waste;

[0006] 2) High energy consumption: Multiple crystallizations require repeated heating and cooling, which results in high energy consumption and low efficiency;

[0007] 3) Risk of endotoxin residues: Traditional methods for endotoxin removal have insufficient retention capacity for endotoxin (LPS) and low removal efficiency (final product content ≥ 0.5EU / mg), requiring additional purification steps. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to provide a green preparation method for purifying oxytetracycline hydrochloride based on a multi-stage filter membrane. The method adopts distributed gradient filtration technology and directly intercepts impurities and endotoxin aggregates of different particle sizes through the physical screening effect of the PTFE filter membrane, thereby achieving efficient purification and environmentally friendly emission reduction.

[0009] In order to solve the above technical problems, the technical solutions adopted by the present invention are as follows:

[0010] A green preparation method for oxytetracycline hydrochloride purification based on multi-stage filtration membranes comprises the following steps:

[0011] 1) Add anhydrous calcium chloride and oxytetracycline to methanol and stir to dissolve;

[0012] 2) filtering the mixed solution of step 1) through a filter membrane, cooling the filtrate and adding an acid-alcohol solution to adjust the pH for acidification;

[0013] 3) filtering the acidified solution obtained in step 2) through a filter membrane in two stages, and cooling the filtrate until crystallization occurs;

[0014] 4) The filtrate is washed with refrigerated methanol and dried to obtain oxytetracycline hydrochloride.

[0015] Furthermore, in the step 1), the mass ratio of anhydrous calcium chloride to oxytetracycline is 1-3:40-100.

[0016] Furthermore, in step 1), the dissolution temperature is 40-45°C

[0017] Furthermore, in the step 2), the pore size of the sintered filter membrane is 10 μm.

[0018] Furthermore, in the step 2), the cooling temperature is 25-30°C.

[0019] Furthermore, in the step 2), the pH is adjusted to 1.5 to 1.8.

[0020] Furthermore, in step 3), the pore sizes of the two-stage filtration membranes are 0.2 μm and 0.1 μm respectively.

[0021] Furthermore, in the step 3), the cooling temperature of the filtrate is 0-5° C., and the crystallization time is 2 h.

[0022] Furthermore, in step 4), the bacterial endotoxin content is <0.2 EU / mg.

[0023] Compared with the prior art, the present invention has the following advantages:

[0024] (1) The present invention adopts distributed gradient filtration technology, which directly intercepts impurities and endotoxin aggregates of different particle sizes through the physical screening effect of PTFE filter membrane, thereby achieving efficient purification and environmentally friendly emission reduction.

[0025] (2) The present invention uses two-stage filtration instead of adsorption, removing large particle impurities through 10 μm coarse filtration and combining 0.2 μm and 0.1 μm ultrafiltration to intercept endotoxins. No activated carbon adsorption is required, and the amount of solid waste is reduced by more than 90%.

[0026] (3) The present invention directly acidifies to salt in a methanol system through in-situ acidification and filtration. When the pH is less than 2, bacterial endotoxins easily form large-size aggregates. By filtration, not only can the endotoxins be removed, but also the introduction of inorganic salt impurities in the traditional aqueous solution system is avoided.

[0027] (4) The present invention utilizes filter membrane regeneration technology and adopts methanol-dilute hydrochloric acid mixed solution for backwashing, and the filter membrane can be reused ≥10 times.

[0028] (5) The methanol of the present invention is recycled, and the filtrate is distilled to recover methanol, and the solvent utilization rate is ≥95%. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1This is a high performance liquid chromatogram of oxytetracycline hydrochloride prepared in Example 1 of the present application. DETAILED DESCRIPTION

[0030] The present invention will be further illustrated below with reference to specific examples. The examples are implemented based on the technical solutions of the present invention. It should be understood that these examples are only used to illustrate the present invention and are not used to limit the scope of the present invention.

[0031] In the following examples, the PTFE filter membrane was purchased from Jinchun Environmental Protection Technology, precision filtration membrane-SC series, with a pore size of 0.1-10 μm.

[0032] In the following examples, oxytetracycline was purchased from Datong Tongxing Antibiotics Co., Ltd., and anhydrous calcium chloride (AR) was purchased from Aladdin.

[0033] In the following examples, insoluble impurities were removed by 10 μm filtration (oxytetracycline was completely dissolved); the particle size of individual endotoxins was 1 to 5 nm, and the size of aggregates ranged from tens to hundreds of nanometers.

[0034] The bacterial endotoxin detection method in the following examples is: refer to the gel method in the 2020 edition of the "Pharmacopoeia of the People's Republic of China" for detection: the procoagulant in the horseshoe crab reagent reacts with the endotoxin to form an irreversible gel-like substance, and the result is determined by observing the firmness of the gel with the naked eye (whether the gel flows when the ampoule is inverted).

[0035] The horseshoe crab reagent used was from Zhanjiang Bokang Marine Biological Co., Ltd., with a specification of 0.1 mL / tube and a sensitivity of 0.125 EU / mL.

[0036] Example 1

[0037] A green preparation method for oxytetracycline hydrochloride purification based on multi-stage filtration membranes comprises the following steps:

[0038] At room temperature, measure 320mL of methanol, add 1.2g of anhydrous calcium chloride and 40g of oxytetracycline, heat to 40-45℃ and stir to dissolve. The solution is filtered through a 10μm PTFE filter membrane to remove insoluble impurities, the filtrate is cooled to 25-30℃, 10wt% hydrogen chloride-methanol solution is added to adjust the pH to 1.5-1.8, and stirred for 30min to fully acidify. The acidified liquid is filtered through a 0.2μm PTFE filter membrane and a 0.1μm PTFE filter membrane respectively to retain endotoxin aggregates and micron-sized residues, and the filtrate is cooled to 0-5℃ and kept warm for crystallization for 2h. After filtration, it is washed with frozen methanol 3 times (20mL×3), and vacuum dried at 60℃ for 2h to obtain 37.8g of oxytetracycline hydrochloride with a mass yield of 94.5%. The high-performance liquid chromatogram of oxytetracycline hydrochloride is shown as follows Figure 1 As shown; According to the European Pharmacopoeia standard, calculated on anhydrous basis, contains oxytetracycline hydrochloride (C 22 H 24N2O9·HCl) 97.5%; bacterial endotoxin content: <0.2EU / mg.

[0039] Example 2

[0040] A green preparation method for oxytetracycline hydrochloride purification based on multi-stage filtration membranes comprises the following steps:

[0041] At room temperature, 8L of methanol was measured, 25g of anhydrous calcium chloride and 1kg of oxytetracycline were added, and the temperature was raised to 40-45°C and stirred to dissolve. The solution was filtered through a 10μm PTFE filter membrane to remove insoluble impurities, the filtrate was cooled to 25-30°C, 10wt% hydrogen chloride-methanol solution was added to adjust the pH to 1.5-1.8, and stirred for 30min to fully acidify. The acidified solution was filtered through a 0.2μm PTFE filter membrane and a 0.1μm PTFE filter membrane respectively to retain endotoxin aggregates and micron-sized residues. The filtrate was cooled to 0-5°C and kept warm for crystallization for 2h, then centrifuged, washed 3 times with frozen methanol (300mL×3), and vacuum dried at 60°C for 2h to obtain 952g of oxytetracycline hydrochloride with a mass yield of 95.2%; according to the European Pharmacopoeia standard, the content of oxytetracycline hydrochloride (C 22 H 24 N2O9·HCl) 97.46%; bacterial endotoxin content: <0.2EU / mg.

[0042] Comparative Example 1

[0043] At room temperature, 320 mL of methanol was measured, 1.2 g of anhydrous calcium chloride and 40 g of oxytetracycline were added, the temperature was raised to 40-45 ° C, and the mixture was stirred and dissolved. 0.8 g of activated carbon was added, stirred for 30 min, filtered, and the filtrate was cooled to 25-30 ° C, 10 wt% hydrogen chloride-methanol solution was added to adjust the pH to 1.5-1.8, and the filtrate was cooled to 0-5 ° C and kept warm for crystallization for 2 h. After filtration, the mixture was washed with chilled methanol 3 times (20 mL × 3), and vacuum dried at 60 ° C for 2 h to obtain 37.0 g of oxytetracycline hydrochloride with a mass yield of 92.5%. According to the European Pharmacopoeia standard, the content of oxytetracycline hydrochloride (C 22 H 24 N2O9·HCl) 97.22%; bacterial endotoxin content: 0.8EU / mg positive, not meeting the pharmacopoeia requirements.

[0044] Comparative Example 2

[0045] Into the reactor, 30 g of oxytetracycline, 135 mL of methanol, and 3 mL of methanolic hydrochloride were sequentially added, stirred for 30 min, heated to 50 ° C to dissolve all the oxytetracycline, added 0.6 g of activated carbon, continued to heat to 57 ° C, stirred for 15 min and filtered, the filtrate was cooled to room temperature, and then 5 g of dry hydrogen chloride gas was introduced under stirring, gradually cooled to 2 ° C, stirred for 4 h, filtered, and the filter cake was washed with 15 mL of cold methanol and dried to obtain 28.1 g of oxytetracycline hydrochloride, with a mass yield of 93.7%. According to the European Pharmacopoeia standard, the content of oxytetracycline hydrochloride (C 22 H 24 N2O9·HCl) 97.32%, bacterial endotoxin 1.6EU / mg positive, not meeting the pharmacopoeia requirements.

[0046] By comparing Examples 1 to 2 with Comparative Documents 1 to 2, it can be seen that the activated carbon used in the prior art also adsorbs the product during the process of adsorbing impurities, thereby resulting in a decrease in product yield; at the same time, because the adsorption capacity of activated carbon for endotoxins is limited, the endotoxin residue in the product is difficult to meet the requirements and requires further purification.

[0047] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A green preparation method for oxytetracycline hydrochloride purification based on multi-stage filtration membrane, characterized in that: The following steps are involved: 1) Add anhydrous calcium chloride and oxytetracycline to methanol and stir to dissolve; 2) filtering the mixed solution of step 1) through a filter membrane, cooling the filtrate and adding an acid-alcohol solution to adjust the pH for acidification; 3) filtering the acidified solution obtained in step 2) through a filter membrane in two stages, and cooling the filtrate until crystallization occurs; 4) The filtrate is washed with refrigerated methanol and dried to obtain oxytetracycline hydrochloride.

2. The green preparation method of oxytetracycline hydrochloride purification based on multi-stage membrane filtration according to claim 1, characterized in that: In the step 1), the mass ratio of anhydrous calcium chloride to oxytetracycline is 1-3:40-100.

3. The green preparation method based on multi-stage membrane purification of oxytetracycline hydrochloride according to claim 1, characterized in that: In the step 1), the dissolving temperature is 40-45°C.

4. The green preparation method based on multi-stage membrane purification of oxytetracycline hydrochloride according to claim 1, characterized in that: In the step 2), the pore size of the sintered filter membrane is 10 μm.

5. The green preparation method of oxytetracycline hydrochloride purification based on multi-stage membrane filtration according to claim 1, characterized in that: In the step 2), the cooling temperature is 25-30°C.

6. The green preparation method of oxytetracycline hydrochloride purification based on multi-stage membrane filtration according to claim 1, characterized in that: In the step 2), the pH is adjusted to 1.5-1.

8.

7. The green preparation method of oxytetracycline hydrochloride purification based on multi-stage membrane filtration according to claim 1, characterized in that: In the step 3), the pore sizes of the two-stage filtration membranes are 0.2 μm and 0.1 μm respectively.

8. The green preparation method of oxytetracycline hydrochloride purification based on multi-stage membrane filtration according to claim 1, characterized in that: In the step 3), the cooling temperature of the filtrate is 0-5° C., and the crystallization time is 2 h.

9. The green preparation method of oxytetracycline hydrochloride purification based on multi-stage membrane filtration according to claim 1, characterized in that: In the step 4), the bacterial endotoxin content is <0.2 EU / mg.

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