A preparation method of aureomycin hydrochloride
By employing flocculation, acid hydrolysis, and recrystallization processes on the chlortetracycline fermentation broth, the problem of high impurity content in existing preparation processes has been solved, enabling the industrial production of high-purity chlortetracycline hydrochloride and meeting the GMP requirements for high-quality pharmaceuticals.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- PUCHENG CHIA TAI BIOCHEM
- Filing Date
- 2026-03-24
- Publication Date
- 2026-07-31
AI Technical Summary
The existing preparation process yields chlortetracycline hydrochloride with high levels of tetracycline and tetra-differential chlortetracycline, resulting in low effective chlortetracycline content. This makes it difficult to meet the requirements for high-quality drugs, and the drugs are highly toxic, making it difficult to meet the requirements of GMP plants.
A solid-liquid separation was performed on the acidified chlortetracycline fermentation broth using a flocculant. After forming the liquid phase, calcium salts, magnesium salts, and alkaline reagents were added to form chlortetracycline calcium magnesium double salt. After dissolution, acid hydrolysis was carried out to form coarse crystals. Then, it was mixed with magnesium chloride ethanol solution and impurity removal agent to dissolve and remove impurities. Finally, pure chlortetracycline hydrochloride was obtained by recrystallization.
The effective chlortetracycline content of chlortetracycline hydrochloride was increased to over 93.5%, while the content of tetracycline and tetravariant chlortetracycline was reduced to below 4%, thus lowering the preparation cost, simplifying the operation process, and making it suitable for industrial production.
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Figure CN122497658A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of veterinary drug raw material technology, specifically to a method for preparing chlortetracycline hydrochloride. Background Technology
[0002] Chlortetracycline hydrochloride, also known as tetracycline hydrochloride, is mainly used to treat conjunctivitis, trachoma, and other eye conditions. Currently, chlortetracycline hydrochloride is primarily prepared by fermentation with *Streptomyces aureus*. The fermentation broth is purified step-by-step through processes such as acidification, resalting, crude crystallization, extraction and dissolution, and secondary recrystallization. The main impurities in chlortetracycline hydrochloride obtained through this process are tetracycline (TC) and 4-EpiCTC. Tetracycline and chlortetracycline both belong to the tetracycline class of antibiotics and are produced during the *Streptomyces aureus* fermentation process. They also share similar structures and properties, making removal difficult. European standards require chlortetracycline hydrochloride to have an effective chlortetracycline content (CTC, calculated as chlortetracycline hydrochloride) ≥ 89.5%, a tetracycline content ≤ 6.0%, and a 4-EpiCTC content ≤ 4.0% (both calculated using the area normalization method based on standard samples). The existing preparation process yields chlortetracycline hydrochloride with an effective chlortetracycline content of 91–92.5%, tetracycline content of 4.5–6%, and tetrachlortetracycline content of 1.5–4%. However, the existing preparation process still results in high levels of tetracycline and tetrachlortetracycline, low effective chlortetracycline content, short shelf life, and high toxicity due to high impurity content. This makes it difficult to meet the requirements of GMP (Good Manufacturing Practice) factories that demand high-quality chlortetracycline hydrochloride. Summary of the Invention
[0003] In view of this, the purpose of this invention is to provide a method for preparing chlortetracycline hydrochloride. The chlortetracycline hydrochloride prepared by the method provided by this invention has a high effective chlortetracycline content and low content of impurities such as tetracycline and tetradextrin.
[0004] To achieve the above-mentioned objectives, the present invention provides the following technical solution:
[0005] This invention provides a method for preparing chlortetracycline hydrochloride, comprising the following steps:
[0006] The acidified chlortetracycline fermentation broth was flocculated with a flocculant, followed by solid-liquid separation to obtain the liquid phase; the chlortetracycline fermentation broth contained Streptomyces aureus hyphae, chlortetracycline, tetracycline, and tetra-differentiated chlortetracycline;
[0007] The liquid phase, calcium salt, magnesium salt, and alkaline reagent are mixed to obtain chlortetracycline calcium magnesium complex salt;
[0008] The calcium magnesium chlortetracycline salt was dissolved in ethanol, and hydrochloric acid was added to carry out an acid hydrolysis reaction to form a precipitate, thus obtaining crude chlortetracycline hydrochloride crystals.
[0009] The crude chlortetracycline hydrochloride crystals, magnesium chloride ethanol solution, and impurity remover are mixed and dissolved to remove impurities, resulting in an extract; the impurity remover includes one or more of ammonium bicarbonate, ammonium sulfate, ammonium nitrate, carbamide, and ammonium chloride;
[0010] The extract was mixed with the second hydrochloric acid and recrystallized to obtain pure chlortetracycline hydrochloride.
[0011] Preferably, the mass ratio of the impurity remover to the crude chlortetracycline hydrochloride crystals is 0.2 to 1:100.
[0012] Preferably, the recrystallization process further includes drying and pulverizing the chlortetracycline hydrochloride wet crystals obtained from the recrystallization process sequentially;
[0013] The particle size of the pure chlortetracycline hydrochloride obtained by pulverization is 10-30 μm.
[0014] Preferably, the pH value for dissolving and removing impurities is 6.5–7;
[0015] The pH adjuster used to adjust the pH value for dissolution and impurity removal includes ammonia.
[0016] Preferably, the chemical potency of the chlortetracycline fermentation broth is 25,000 to 30,000 units / mL.
[0017] Preferably, based on the chemical potency of the chlortetracycline fermentation broth, the amount of ethanol used is 2.8–3.2 L / 100 million units;
[0018] The mass concentration of the first hydrochloric acid is 29-33%;
[0019] Based on the chemical potency of the chlortetracycline fermentation broth, the amount of the first hydrochloric acid used is 1.3 to 1.6 L / 100 million units.
[0020] Preferably, the concentration of the magnesium chloride ethanol solution is 50–90 g / L;
[0021] Based on the chemical potency of the chlortetracycline fermentation broth, the amount of magnesium chloride ethanol solution used is 9.5–10.5 L / 100 million units.
[0022] Preferably, the acidified solution of the chlortetracycline fermentation broth is obtained by acidifying the chlortetracycline fermentation broth;
[0023] The acidification reagents used include oxalic acid and hydrochloric acid;
[0024] The mass-to-volume ratio of oxalic acid and chlortetracycline fermentation broth is 1.5–2.5 g: 100 mL;
[0025] The acidification temperature is 0–5°C.
[0026] Preferably, the flocculant comprises sodium prussiate of potassium and zinc sulfate;
[0027] The mass-to-volume ratio of sodium chlorophenate and chlortetracycline fermentation broth is 0.1–0.2 g: 100 mL;
[0028] The mass-to-volume ratio of zinc sulfate and chlortetracycline fermentation broth is 0.1–0.3 g: 100 mL.
[0029] Preferably, the magnesium salt comprises magnesium chloride;
[0030] The mass-to-volume ratio of the magnesium salt to the liquid phase is 0.1–0.35 g: 100 mL;
[0031] The calcium salt includes calcium carbonate; the mass-to-volume ratio of the calcium salt to the liquid phase is 0.05–0.35 g: 100 mL;
[0032] The alkaline reagent includes ammonia water and / or an aqueous solution of sodium hydroxide;
[0033] The temperature at which the liquid phase, calcium salt, magnesium salt, and alkaline reagent are mixed is 0–5°C.
[0034] This invention provides a method for preparing chlortetracycline hydrochloride, comprising the following steps: flocculating the acidified chlortetracycline fermentation broth with a flocculant and then separating the solid and liquid phases to obtain a liquid phase; the chlortetracycline fermentation broth contains *Streptomyces aureus* hyphae, chlortetracycline, tetracycline, and tetra-achromic acid; mixing the liquid phase, calcium salt, magnesium salt, and alkaline reagent to obtain chlortetracycline calcium-magnesium complex salt; dissolving the chlortetracycline calcium-magnesium complex salt in ethanol, adding a first hydrochloric acid to perform an acid hydrolysis reaction to form a precipitate, obtaining crude chlortetracycline hydrochloride crystals; mixing the crude chlortetracycline hydrochloride crystals, magnesium chloride ethanol solution, and a purification agent to dissolve and remove impurities, obtaining an extract; the purification agent includes one or more of ammonium bicarbonate, ammonium nitrate, and carbamide; mixing the extract with a second hydrochloric acid for recrystallization to obtain pure chlortetracycline hydrochloride. The method for preparing chlortetracycline hydrochloride provided by this invention involves adding a specific impurity removal reagent (one or more of ammonium bicarbonate, ammonium nitrate, and carbamide) during the extraction and dissolution step. This achieves selective removal of the structural analogs tetracycline and tetradextrin, resulting in a pure chlortetracycline hydrochloride with an effective chlortetracycline content >93.5%, a tetracycline content <4%, and a tetradextrin content <1.5%, indicating high-quality chlortetracycline hydrochloride. Furthermore, the preparation method provided by this invention performs impurity removal simultaneously during the dissolution (extraction) step, eliminating the need for additional impurity removal steps, reducing preparation costs, simplifying operation, and making it suitable for industrial-scale preparation of chlortetracycline hydrochloride. Attached Figure Description
[0035] Figure 1 This is a flowchart illustrating the preparation process of chlortetracycline hydrochloride in this invention.
[0036] Figure 2 This is a flowchart of the traditional preparation process for chlortetracycline hydrochloride. Detailed Implementation
[0037] This invention provides a method for preparing chlortetracycline hydrochloride, comprising the following steps:
[0038] The acidified chlortetracycline fermentation broth was flocculated with a flocculant, followed by solid-liquid separation to obtain the liquid phase; the chlortetracycline fermentation broth contained Streptomyces aureus hyphae, chlortetracycline, tetracycline, and tetra-differentiated chlortetracycline;
[0039] The liquid phase, calcium salt, magnesium salt, and alkaline reagent are mixed to obtain chlortetracycline calcium magnesium complex salt;
[0040] The calcium magnesium chlortetracycline salt was dissolved in ethanol, and hydrochloric acid was added to carry out an acid hydrolysis reaction to form a precipitate, thus obtaining crude chlortetracycline hydrochloride crystals.
[0041] The crude chlortetracycline hydrochloride crystals, magnesium chloride ethanol solution, and a purifying agent are mixed and dissolved to remove impurities, resulting in an extract; the purifying agent includes one or more of ammonium bicarbonate, ammonium nitrate, and carbamide.
[0042] The extract was mixed with the second hydrochloric acid and recrystallized to obtain pure chlortetracycline hydrochloride.
[0043] Unless otherwise specified, the materials and equipment used in this invention are all commercially available products in the field.
[0044] Figure 1 The following is a flow chart of the preparation process of chlortetracycline hydrochloride in this invention, in conjunction with... Figure 1 The preparation method of chlortetracycline hydrochloride in this invention will be described in detail.
[0045] This invention employs a flocculant to flocculate the acidified chlortetracycline fermentation broth, followed by solid-liquid separation to obtain the liquid phase.
[0046] In this invention, the chlortetracycline fermentation broth contains *Streptomyces aureus* mycelium, chlortetracycline, tetracycline, and tetrachlortetracycline. The chlortetracycline fermentation broth may also contain unutilized material residues from the culture medium, specifically one or more of corn starch, soybeans, peanuts, and yeast powder. The chemical potency of the chlortetracycline fermentation broth can be 25,000–30,000 units / mL, specifically 25,000 units / mL, 26,000 units / mL, 27,000 units / mL, 28,000 units / mL, 29,000 units / mL, or 30,000 units / mL.
[0047] In this invention, the acidified chlortetracycline fermentation broth can be obtained by acidifying the chlortetracycline fermentation broth. In this invention, the acidifying reagents used for acidification may include oxalic acid and hydrochloric acid; the mass-to-volume ratio of oxalic acid to chlortetracycline fermentation broth can be 1.5–2.5 g:100 mL, specifically 1.5 g:100 mL, 1.8 g:100 mL, 2 g:100 mL, 2.3 g:100 mL, or 2.5 g:100 mL. This invention uses oxalic acid to acidify and disrupt the cell walls of *Streptomyces aureus* hyphae in the chlortetracycline fermentation broth, releasing chlortetracycline from the hyphae (intracellular layer) and improving the filtration rate of plate and frame filtration.
[0048] In this invention, the chlortetracycline fermentation broth may be mixed with water before mixing with the acidifying reagent. In this invention, the water may include purified water; the volume ratio of the chlortetracycline fermentation broth to water may be 1:0.5 to 1.2, specifically 1:0.5, 1:0.8, 1:1, or 1:1.2.
[0049] In this invention, the acidification temperature can be 0 to 5°C, specifically 0°C, 1°C, 2°C, 3°C, 4°C or 5°C.
[0050] In this invention, the acidification may include the following steps: mixing chlortetracycline fermentation broth with oxalic acid to obtain a pre-acidified solution; adjusting the pH of the pre-acidified solution to 1.1–1.4 with hydrochloric acid. This invention does not have specific limitations on the concentration and amount of hydrochloric acid, as long as the pH value reaches 1.1–1.4. By adjusting the pH to 1.1–1.4 with hydrochloric acid, this invention maximizes the dissolution of intracellular chlortetracycline, improving the yield of chlortetracycline hydrochloride. Furthermore, using hydrochloric acid, which is less expensive than oxalic acid, helps reduce preparation costs.
[0051] In this invention, the flocculant may include sodium prussiate of Taurine and zinc sulfate. The mass-to-volume ratio of sodium prussiate of Taurine to chlortetracycline fermentation broth can be 0.1–0.2 g:100 mL, specifically 0.1 g:100 mL, 0.12 g:100 mL, 0.15 g:100 mL, 0.17 g:100 mL, or 0.2 g:100 mL; the mass-to-volume ratio of zinc sulfate to chlortetracycline fermentation broth can be 0.1–0.3 g:100 mL, specifically 0.1 g:100 mL, 0.15 g:100 mL, 0.2 g:100 mL, 0.25 g:100 mL, or 0.3 g:100 mL. This invention uses sodium prussiate of Taurine and zinc sulfate for flocculation, aiming to separate large molecular weight bacterial proteins and residual carbon and nitrogen sources from the fermentation broth, facilitating their removal from the solids during subsequent plate and frame filtration.
[0052] In this invention, the mixing of the acidifying liquid and the flocculant may specifically include the following steps: firstly mixing the acidifying liquid and sodium ferrous sulfate to obtain a first mixed solution; secondly mixing the first mixed solution with zinc sulfate. In this invention, the first mixing time can be 20–30 min, specifically 20 min, 22 min, 25 min, 27 min, or 30 min; the second mixing time can be 20–30 min, specifically 20 min, 22 min, 25 min, 27 min, or 30 min.
[0053] In this invention, the solid-liquid separation may include filtration, specifically plate and frame filtration; the plate and frame filtration includes performing a first plate and frame filtration and a second plate and frame filtration in sequence.
[0054] After completing the first plate and frame filtration, the present invention may further include acid washing of the first filter residue obtained from the first plate and frame filtration to obtain a washing liquid; combining the washing liquid and the first filter liquid obtained from the first plate and frame filtration, and performing a second plate and frame filtration. In the present invention, the acid used for acid washing may specifically be an aqueous solution of hydrochloric acid; the pH value of the acid may be 0.5 to 1, specifically 0.5, 0.6, 0.8, or 1; the acid washing may specifically be a top washing.
[0055] After obtaining the liquid phase, the present invention mixes the liquid phase, calcium salt, magnesium salt and alkaline reagent to obtain chlortetracycline calcium magnesium complex salt.
[0056] In this invention, the magnesium salt may include magnesium chloride; the mass-to-volume ratio of the magnesium salt to the liquid phase may be 0.1–0.35 g: 100 mL, specifically 0.1 g: 100 mL, 0.15 g: 100 mL, 0.2 g: 100 mL, 0.25 g: 100 mL, 0.3 g: 100 mL, or 0.35 g: 100 mL; the calcium salt may include calcium carbonate; the mass-to-volume ratio of the calcium salt to the liquid phase may be 0.05–0.35 g: 100 mL, specifically 0.1 g: 100 mL, 0.15 g: 100 mL, 0.2 g: 100 mL, 0.25 g: 100 mL, 0.3 g: 100 mL, or 0.35 g: 100 mL; the alkaline reagent includes ammonia. The present invention does not have any particular limitation on the amount and concentration of the alkaline reagent, as long as the pH value of the mixed solution is 7.6 to 7.9, specifically 7.6, 7.7, 7.8 or 7.9.
[0057] In this invention, the mixing of the liquid phase, calcium salt, magnesium salt, and alkaline reagent can specifically involve: a third mixing of the liquid phase and magnesium salt to obtain a third mixed solution; a fourth mixing of the third mixed solution and calcium salt, and adjustment of the pH value to 7.6–7.9 using an alkaline reagent. In this invention, the third mixing time can be 10–20 min, specifically 10 min, 12 min, 15 min, 18 min, or 20 min; the fourth mixing time can also be 10–20 min, specifically 10 min, 12 min, 15 min, 18 min, or 20 min. In this invention, the mixing temperature of the liquid phase, calcium salt, magnesium salt, and alkaline reagent can be 0–5°C, specifically 0°C, 1°C, 2°C, 3°C, 4°C, or 5°C. This invention achieves the separation of chlortetracycline calcium magnesium salt precipitation and alkaline protein by adding calcium and magnesium salts, causing the chlortetracycline in the liquid phase to form a chlortetracycline calcium magnesium complex salt precipitate, while the basic protein is retained in the liquid phase.
[0058] In this invention, the mixture obtained by mixing the liquid phase, calcium salt, magnesium salt, and alkaline reagent further includes filtration, washing the resulting solid until neutral, and drying to obtain chlortetracycline calcium magnesium double salt. In this invention, the filtration may include plate and frame filtration; the washing may include water washing.
[0059] After obtaining the chlortetracycline calcium-magnesium complex salt, this invention dissolves the chlortetracycline calcium-magnesium complex salt in ethanol, adds hydrochloric acid to carry out an acid hydrolysis reaction to form a precipitate, and obtains crude chlortetracycline hydrochloride crystals. This invention achieves the separation of crude chlortetracycline hydrochloride crystals from calcium-magnesium ions and acidic proteins through an acid hydrolysis reaction, allowing the acidic protein and calcium-magnesium ions to remain in the solution.
[0060] In this invention, based on the chemical potency of the chlortetracycline fermentation broth, the amount of ethanol used can be 2.8–3.2 L / 100 million units, specifically 2.8 L / 100 million units, 2.9 L / 100 million units, 3 L / 100 million units, 3.1 L / 100 million units, or 3.2 L / 100 million units. In this invention, the mass concentration of the first hydrochloric acid can be 29–33%, specifically 29%, 30%, 31%, 32%, or 33%; based on the chemical potency of the chlortetracycline fermentation broth, the amount of the first hydrochloric acid used can be 1.3–1.6 L / 100 million units, specifically 1.3 L / 100 million units, 1.4 L / 100 million units, 1.5 L / 100 million units, or 1.6 L / 100 million units.
[0061] In this invention, the holding temperature for the acidolysis reaction can be 44-48°C, specifically 44°C, 45°C, 46°C, 47°C or 48°C; the time for the acidolysis reaction can be 45-60 min, specifically 45 min, 50 min, 55 min or 60 min.
[0062] After the acidolysis reaction is completed, the present invention may further include filtering the crude chlortetracycline hydrochloride crystal solution obtained from the acidolysis reaction, washing the resulting solid, and obtaining crude chlortetracycline hydrochloride crystals. In the present invention, the filtration may include plate and frame filtration. In the present invention, the washing includes sequential water washing and alcohol washing; the alcohol used for alcohol washing may specifically be ethanol; the volume ratio of water used for water washing to alcohol used for alcohol washing may be 3:2; the washing temperature may be 44-48°C, specifically 44°C, 45°C, 46°C, 47°C, or 48°C.
[0063] After obtaining crude chlortetracycline hydrochloride crystals, the present invention mixes the crude chlortetracycline hydrochloride crystals, magnesium chloride ethanol solution, and impurity removal agent to dissolve and remove impurities, thereby obtaining an extract.
[0064] In this invention, the impurity remover includes one or more of ammonium bicarbonate, ammonium sulfate, ammonium nitrate, carbamide, and ammonium chloride; the mass ratio of the impurity remover to crude chlortetracycline hydrochloride crystals can be 0.2–1:100, specifically 0.2:100, 0.4:100, 0.6:100, 0.8:100, or 1:100; the concentration of the magnesium chloride ethanol solution can be 50–90 g / L, specifically 50 g / L, 60 g / L, 70 g / L, 80 g / L, or 90 g / L; based on the chemical potency of the chlortetracycline fermentation broth, the amount of magnesium chloride ethanol solution used can be 9.5–10.5 L / 100 million units, specifically 9.5 L / 100 million units, 9.8 L / 100 million units, 10 L / 100 million units, 10.2 L / 100 million units, or 10.5 L / 100 million units.
[0065] In this invention, the pH value for dissolving and removing impurities can be 6.5–7, specifically 6.5, 6.6, 6.7, 6.8, 6.9, and 7. The pH adjusting agent used for dissolving and removing impurities can include ammonia water and / or sodium hydroxide aqueous solution. This invention does not have a specific limitation on the concentration of the ammonia water and sodium hydroxide aqueous solution, as long as the pH value for dissolving and removing impurities is adjusted to 6.5–7. In this invention, adjusting the pH value for dissolving and removing impurities can specifically include the following steps: mixing the solution obtained by mixing the crude chlortetracycline hydrochloride crystals, magnesium chloride ethanol solution, and impurity remover with ammonia water for a fifth mixing. In this invention, the temperature of the fifth mixing can be 10–30°C, specifically 10°C, 15°C, 20°C, 25°C, or 30°C; the time of the fifth mixing can be 20–30 min, specifically 20 min, 22 min, 24 min, 26 min, 28 min, or 30 min.
[0066] In this invention, mixing the crude chlortetracycline hydrochloride crystals, magnesium chloride ethanol solution, and impurity remover may specifically include the following steps: mixing the crude chlortetracycline hydrochloride crystals and magnesium chloride ethanol solution, and then adding the impurity remover for further mixing.
[0067] After dissolution and impurity removal, the present invention may further include subjecting the impurity-removed liquid obtained from the dissolution and impurity removal to a first filtration, washing the resulting solid with a magnesium chloride ethanol solution, and combining the washing solution and the filtrate obtained from the first filtration for a second filtration to obtain an extract. In the present invention, the first filtration may include plate and frame filtration; the concentration of the magnesium chloride ethanol solution may be 50–90 g / L, specifically 50 g / L, 60 g / L, 70 g / L, 80 g / L, or 90 g / L; the second filtration may include microporous membrane filtration; the pore size of the microporous membrane may be 0.11–0.22 μm, specifically 0.11 μm, 0.15 μm, 0.18 μm, or 0.22 μm.
[0068] After obtaining the extract, the present invention mixes the extract with the second hydrochloric acid and recrystallizes to obtain pure chlortetracycline hydrochloride. Through recrystallization, the present invention further removes residual calcium and magnesium ions and acidic proteins from the pure chlortetracycline hydrochloride.
[0069] In this invention, the mass concentration of the second hydrochloric acid can be 29-33%, specifically 29%, 30%, 31%, 32%, or 33%; the volume ratio of the extract to the second hydrochloric acid can be 100:8-14, specifically 100:8, 100:10, 100:12, or 100:14. In this invention, the recrystallization temperature can be 42-48°C, specifically 42°C, 44°C, 46°C, or 48°C; the recrystallization time can be 40-60 min, specifically 40 min, 45 min, 50 min, 55 min, or 60 min.
[0070] In this invention, the mixing of the extract and the second hydrochloric acid may include the following steps: mixing the extract and a portion of the second hydrochloric acid to obtain a partial mixture; and mixing the partial mixture with the remaining second hydrochloric acid. In this invention, the volume ratio of the extract to the portion of the second hydrochloric acid can be 100:2 to 3, specifically 100:2, 100:2.5, or 100:3; the volume ratio of the extract to the remaining second hydrochloric acid can be 100:6 to 11, specifically 100:6, 100:7, 100:8, 100:9, 100:10, or 100:11.
[0071] After recrystallization, the present invention may further include centrifuging the recrystallized liquid obtained from recrystallization, washing the resulting solid sequentially with water and ethanol, and drying it to obtain pure chlortetracycline hydrochloride. In the present invention, the water may specifically be hot water; the drying may include spin drying.
[0072] In this invention, the recrystallization process may further include drying and pulverizing the chlortetracycline hydrochloride wet crystals obtained from recrystallization in sequence; in this invention, the median particle size of the pulverized chlortetracycline hydrochloride pure product may be 10-30 μm, specifically 10 μm, 15 μm, 20 μm, 25 μm or 30 μm.
[0073] In this invention, the drying may include airflow drying; the pulverization may include airflow milling; the temperature of the airflow milling may be <10℃, specifically 2℃, 4℃, 6℃, 8℃, or 9℃; the airflow pressure of the airflow milling may be 0.8~1MPa, specifically 0.8MPa, 0.85MPa, 0.9MPa, 0.95MPa, or 1MPa. This invention, through airflow milling, improves the water solubility of the obtained chlortetracycline hydrochloride pure product to >1g / 100mL, which is a significant improvement compared to the solubility of chlortetracycline hydrochloride obtained without airflow milling (0.3~0.4g / 100mL).
[0074] To further illustrate the present invention, the solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.
[0075] In all embodiments and comparative examples of the present invention, the raw materials and grades used are as follows:
[0076] Oxalic acid, Shandong Fengyuan Chemical Co., Ltd., refined grade, CS250601 batch;
[0077] Hydrochloric acid, Fujian Rongchang Chemical Co., Ltd., CP grade, batch YS250602;
[0078] Zinc sulfate, Shanghai Yangxin Chemical Co., Ltd., feed grade, batch SX250601;
[0079] Sodium prussiatetrafluoroethylene (SPF), Hebei Chengxin Chemical Co., Ltd., CP grade, batch YN250601;
[0080] Magnesium chloride, Xining Zeer Trading Co., Ltd., feed grade;
[0081] (Light) Calcium Carbonate, Jiangxi Mingyuan High-Tech Materials Co., Ltd., TG250603 batch;
[0082] Ethanol, Jiangsu Huating Biotechnology Co., Ltd., refined grade, batch YC250603;
[0083] Impurity remover, Xilong Chemical Co., Ltd., AR grade.
[0084] All raw and auxiliary materials meet the corresponding national quality standards.
[0085] The chlortetracycline fermentation broths in Examples 1-10 and Comparative Examples 1-6 all had a chemical potency of 25,000-30,000 units / mL.
[0086] Example 1
[0087] Cool the chlortetracycline fermentation broth to 5°C, and add purified water with a volume equal to one volume of the chlortetracycline fermentation broth. Then add oxalic acid to the chlortetracycline fermentation broth and adjust the pH to 0.5–1 with hydrochloric acid to obtain an acidified solution. The volume-to-mass ratio of chlortetracycline fermentation broth to oxalic acid is 100 mL: 2 g.
[0088] Add sodium prussiatetramine to the obtained acidified solution and stir for 30 min; then add zinc sulfate and stir for 30 min; filter the resulting flocculated solution using a plate and frame filter press, collect the filtrate, wash the mycelial residue with acidic water with a pH of 1.3–1.8, combine the filtrate and washings, and filter again using a plate and frame filter press to obtain the final product. The mass-to-volume ratio of sodium prussiatetramine to chlortetracycline fermentation broth is 0.1:100 mL; the mass-to-volume ratio of zinc sulfate to chlortetracycline fermentation broth is 0.2 g:100 mL.
[0089] At 5℃, the obtained filtrate was mixed with magnesium chloride and stirred for 15 min; then calcium carbonate was added and stirred for 15 min. The pH was adjusted to 7.6–7.9 with ammonia water. The resulting mixture was then subjected to plate and frame filtration. The obtained solid was washed with water until the pH was neutral and dried to obtain chlortetracycline calcium magnesium double salt. The mass-to-volume ratio of magnesium chloride to filtrate was 0.2 g:100 mL; the mass-to-volume ratio of calcium carbonate to filtrate was 0.25 g:100 mL.
[0090] The obtained chlortetracycline calcium magnesium complex salt was dissolved in ethanol. Hydrochloric acid was added under stirring, and the mixture was stirred until all the chlortetracycline calcium magnesium complex salt was dissolved. The temperature was raised to 44–48°C and maintained for 50 minutes to obtain a crude chlortetracycline hydrochloride crystal solution. The obtained crude chlortetracycline hydrochloride crystal solution was subjected to plate and frame filtration and washed sequentially with water and ethanol preheated to 44–48°C to obtain a crude chlortetracycline hydrochloride crystal solution. The volume ratio of ethanol to water was 3:2. Based on the chemical potency of the chlortetracycline fermentation broth, the amount of ethanol used to dissolve the chlortetracycline calcium magnesium complex salt was 3 L / 100 million units, and the amount of hydrochloric acid used was 1.5 L / 100 million units.
[0091] Crude chlortetracycline hydrochloride crystals were mixed with a 70 g / L magnesium chloride ethanol solution. Based on the chemical potency of the chlortetracycline fermentation broth, the amount of magnesium chloride ethanol solution used was 10 L / 100 million units. A purifying agent was added to the resulting mixture, and the temperature was controlled at 20°C. The pH was adjusted to 6.5–7 using 25% ammonia and 6 mol / L sodium hydroxide aqueous solution. The mixture was stirred for 30 min to dissolve and remove impurities. The resulting purified solution was filtered through a plate and frame filter press to obtain a filtrate and a solid. The solid was washed with a 70 g / L magnesium chloride ethanol solution. The washings and filtrate were combined and filtered through a 0.11 μm microporous membrane. The resulting filtrate was the extract. The volume ratio of ammonia to sodium hydroxide aqueous solution was 1:1, the purifying agent was ammonium chloride and carbamide with a mass ratio of 1:1, and the mass ratio of crude chlortetracycline hydrochloride crystals to the purifying agent was 40:0.08.
[0092] Under stirring conditions, hydrochloric acid equivalent to 2.5% of the volume of the extract was slowly added dropwise, followed by hydrochloric acid equivalent to 6.5% of the volume of the extract. The mixture was stirred until homogeneous, heated to 42–48°C, and kept at this temperature for 50 minutes for recrystallization. The resulting recrystallized solution was centrifuged, and the solution was washed successively with hot water and ethanol, and then dried to obtain wet crystals of chlortetracycline hydrochloride.
[0093] The wet crystals of chlortetracycline hydrochloride were dried to obtain pure chlortetracycline hydrochloride.
[0094] Example 2
[0095] Pure chlortetracycline hydrochloride was prepared using the preparation method provided in Example 1. The only difference from Example 1 is that the mass ratio of crude chlortetracycline hydrochloride crystals to impurity removal agent is 40:0.2.
[0096] Example 3
[0097] Pure chlortetracycline hydrochloride was prepared using the preparation method provided in Example 1. The only difference from Example 1 is that the mass ratio of crude chlortetracycline hydrochloride crystals to impurity removal agent is 40:0.4.
[0098] The median particle size (D) of chlortetracycline hydrochloride in Examples 1-3 50 The value is 50–150 μm.
[0099] Example 4
[0100] Pure chlortetracycline hydrochloride was prepared using the method provided in Example 1. The only difference from Example 1 is that the wet crystals of chlortetracycline hydrochloride were subjected to airflow drying followed by airflow pulverization to obtain pure chlortetracycline hydrochloride. The airflow pulverization was performed at an air pressure of 0.8–1.0 MPa and a temperature <10°C.
[0101] Examples 5-7
[0102] Pure chlortetracycline hydrochloride was prepared using the method provided in Example 4, the only difference being that the mass ratio of crude chlortetracycline hydrochloride crystals to the impurity removal agent was 40:0.2. Three batches were repeated, namely Example 5, Example 6, and Example 7.
[0103] Examples 8-10
[0104] Pure chlortetracycline hydrochloride was prepared using the method provided in Example 4, the only difference being that the mass ratio of crude chlortetracycline hydrochloride crystals to the impurity removal agent was 40:4. Three batches were repeated, namely Example 8, Example 9, and Example 10.
[0105] Median particle size (D) of chlortetracycline hydrochloride in Examples 4-10 50 The thickness is 10–30 μm.
[0106] Comparative Examples 1-6
[0107] Figure 2 The traditional preparation process flow chart for chlortetracycline hydrochloride is shown below. The preparation steps are as follows:
[0108] Pure chlortetracycline hydrochloride was prepared using the preparation method provided in Example 1. The only difference from Example 1 was that no impurity remover was added, and the alkaline reagent used to adjust the pH to 6.5–7 was 25% ammonia solution. The small-scale test and production were each repeated three times, namely, Comparative Example 1, Comparative Example 2, Comparative Example 3, Comparative Example 4, Comparative Example 5, and Comparative Example 6.
[0109] The effective content and impurity content of chlortetracycline in the chlortetracycline hydrochloride prepared in Examples 1-10 and Comparative Examples 1-6 were detected according to the European Pharmacopoeia (EP standard). The results are shown in Table 1. In the table, A is chlortetracycline, B is demethylchlortetracycline, E is chlortetracycline, CTC is chlortetracycline hydrochloride, J is dehydrotetracycline, D is chlortetracycline, H is 2-acetyl-2-deamidochlortetracycline, L is dehydrotetracycline, K is chlortetracycline, I is unknown impurity, and TC is tetracycline hydrochloride.
[0110] Table 1. Effective chlortetracycline content and impurity content in chlortetracycline hydrochloride prepared in Examples 1-10 and Comparative Examples 1-6
[0111]
[0112] As shown in Table 1, the chlortetracycline hydrochloride product prepared by the method provided by the present invention has a TC content of <4.0%, a 4-EpiCTC content of <1.5%, and an effective chlortetracycline content of >93.5% as determined by EP standard. Furthermore, the clear solubility of chlortetracycline hydrochloride after air jet milling is ≥1.0 g / 100 mL. Compared with the traditional preparation process (Comparative Examples 1-6), the TC content in chlortetracycline hydrochloride decreased by 23.2%, the 4-EpiCTC content decreased by 21.4%, the effective CTC content increased by 1.4%, and the solubility of chlortetracycline hydrochloride increased by 77%.
[0113] In summary, this invention, without affecting the overall product yield or requiring additional investment, adopts a green and environmentally friendly production process, increases the effective content of chlortetracycline in chlortetracycline hydrochloride, reduces the proportion of tetracycline and chlortetracycline, and simultaneously improves the solubility of chlortetracycline hydrochloride, providing more possibilities for the product's end-use in aquaculture and the development of new formulations.
[0114] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.
Claims
1. A method for preparing aureomycin hydrochloride, characterized by, Includes the following steps: The acidified chlortetracycline fermentation broth was flocculated with a flocculant, followed by solid-liquid separation to obtain the liquid phase; the chlortetracycline fermentation broth contained Streptomyces aureus hyphae, chlortetracycline, tetracycline, and tetra-differentiated chlortetracycline; The liquid phase, calcium salt, magnesium salt, and alkaline reagent are mixed to obtain chlortetracycline calcium magnesium complex salt; The calcium magnesium chlortetracycline salt was dissolved in ethanol, and hydrochloric acid was added to carry out an acid hydrolysis reaction to form a precipitate, thus obtaining crude chlortetracycline hydrochloride crystals. The crude chlortetracycline hydrochloride crystals, magnesium chloride ethanol solution, and impurity remover are mixed and dissolved to remove impurities, resulting in an extract; the impurity remover includes one or more of ammonium bicarbonate, ammonium sulfate, ammonium nitrate, carbamide, and ammonium chloride; The extract was mixed with the second hydrochloric acid and recrystallized to obtain pure chlortetracycline hydrochloride.
2. The preparation method according to claim 1, characterized in that, The mass ratio of the impurity remover to crude chlortetracycline hydrochloride crystals is 0.2 to 1:
100.
3. The preparation method according to claim 1, characterized in that, The recrystallization process further includes drying and pulverizing the chlortetracycline hydrochloride wet crystals obtained from recrystallization in sequence. The median particle size of the pure chlortetracycline hydrochloride obtained by pulverization is 10–30 μm.
4. The preparation method according to claim 1 or 2, characterized in that, The pH value for dissolving and removing impurities is 6.5–7; The pH adjuster used to adjust the pH value for dissolution and impurity removal includes ammonia.
5. The preparation method according to claim 1, characterized in that, The chemical potency of the chlortetracycline fermentation broth is 25,000 to 30,000 units / mL.
6. The preparation method according to claim 5, characterized in that, Based on the chemical potency of the chlortetracycline fermentation broth, the amount of ethanol used is 2.8–3.2 L / 100 million units; The mass concentration of the first hydrochloric acid is 29-33%; Based on the chemical potency of the chlortetracycline fermentation broth, the amount of the first hydrochloric acid used is 1.3 to 1.6 L / 100 million units.
7. The preparation method according to claim 5, characterized in that, The concentration of the magnesium chloride ethanol solution is 50–90 g / L; Based on the chemical potency of the chlortetracycline fermentation broth, the amount of magnesium chloride ethanol solution used is 9.5–10.5 L / 100 million units.
8. The preparation method according to claim 5, characterized in that, The acidified solution of the chlortetracycline fermentation broth is obtained by acidifying the chlortetracycline fermentation broth; The acidification reagents used include oxalic acid and hydrochloric acid; The mass-to-volume ratio of oxalic acid and chlortetracycline fermentation broth is 1.5–2.5 g: 100 mL; The acidification temperature is 0–5°C.
9. The preparation method according to claim 5, characterized in that, The flocculant includes sodium ferrous sulfate and zinc sulfate; The mass-to-volume ratio of sodium chlorophenate and chlortetracycline fermentation broth is 0.1–0.2 g: 100 mL; The mass-to-volume ratio of zinc sulfate and chlortetracycline fermentation broth is 0.1–0.3 g: 100 mL.
10. The preparation method according to claim 1, characterized in that, The magnesium salt includes magnesium chloride; The mass-to-volume ratio of the magnesium salt to the liquid phase is 0.1–0.35 g: 100 mL; The calcium salt includes calcium carbonate; the mass-to-volume ratio of the calcium salt to the liquid phase is 0.05–0.35 g: 100 mL; The alkaline reagent includes ammonia water and / or an aqueous solution of sodium hydroxide; The temperature at which the liquid phase, calcium salt, magnesium salt, and alkaline reagent are mixed is 0–5°C.