A preparation method of medicinal anhydrous betaine

Abstract

The present invention belongs to the field of fine chemical technology and discloses a method for preparing pharmaceutical anhydrous betaine. This method utilizes calcium synthesis, cation exchange resin chromatography, nanofiltration membrane desalination, reverse osmosis membrane concentration, low-temperature crystallization using an organic solvent, and vacuum drying to produce high-purity, low-ashness pharmaceutical-grade anhydrous betaine. The core approach involves adjusting the pH to 6.5-7.5 with calcium hydroxide to fully convert the betaine into free base. The insoluble phosphates are then removed by filtration, and the filtrate is collected. The filtrate is then filtered through a nanofiltration membrane to retain the small amount of high-valent salts dissolved in the filtrate. The permeate is then collected and concentrated using a reverse osmosis membrane. The method is simple, operates under mild conditions, achieves a large separation capacity, and achieves high purity. The inorganic salt content of the product is less than 0.1%, meeting pharmaceutical requirements. While cost-effective, it is also suitable for large-scale industrial separation and purification.

Description

Technical Field

[0001] The invention belongs to the technical field of fine chemicals and relates to a method for purifying betaine, in particular to a method for preparing medicinal anhydrous betaine. Background Art

[0002] Betaine is a quaternary ammonium, water-soluble alkaloid commonly found in animals and plants. It is the only substance in the human body that can replace folic acid or S-adenosylmethionine as a methyl donor and participates in the methionine cycle and lecithin synthesis. It has physiological functions such as relieving stress, regulating osmotic pressure, increasing appetite, stabilizing vitamins, and reducing fat. Betaine is widely used in the food additive, livestock, and cosmetics industries. Pharmaceutical-grade betaine is used for achlorhydria, atherosclerosis, liver disease, pain relief, rheumatism, and diabetes. However, pharmaceutical-grade anhydrous betaine has very high requirements for product content, purity, and ash content.

[0003] The chemical synthesis method of betaine generally uses chloroacetic acid, sodium hydroxide or sodium carbonate, and trimethylamine as raw materials for neutralization reaction and amination reaction, and obtains the finished betaine through ion exchange chromatography purification or graded precipitation. However, the sodium chloride generated by chemical synthesis in the existing process is highly water-soluble and difficult to completely remove. At the same time, it is also difficult to prepare the product as free base during subsequent processing, resulting in a high ash content and insufficient purity, making the product substandard for pharmaceutical use.

[0004] For example, the published patent CN93109224 discloses a method for obtaining betaine by adsorption with a strong acidic ion exchange resin, desorption with dilute ammonia, concentration, crystallization and desalination. However, this method has the problems of incomplete removal of ammonia in the concentrate, inability to ensure complete release of betaine, and excessive ash content.

[0005] For example, the published patent CN102557970B discloses a method for preparing anhydrous betaine: chloroacetic acid is dissolved in water to form a chloroacetic acid aqueous solution, sodium carbonate is slowly added to the chloroacetic acid aqueous solution under stirring, and after the reaction is completed, a sodium chloroacetate aqueous solution is obtained, trimethylamine is passed into the sodium chloroacetate aqueous solution at 50-60°C for continuous reaction for 3 hours, and anhydrous betaine is obtained after concentration, primary desalination, secondary desalination, electrodialysis desalination, evaporation desalination, and boiling drying. This method has a high yield, but due to the lack of column chromatography purification, there is a risk of incomplete removal of residual byproducts and potential genotoxic impurities in the reaction solution. At the same time, the electrodialysis equipment is expensive and cumbersome to operate, and the product cannot be guaranteed to meet pharmaceutical requirements.

[0006] For example, the published patent CN101591254B discloses a method for removing salt from a betaine solution: a salt-containing betaine solution is synthesized using a chloroacetic acid method, diluted with water, and then subjected to a first-stage semipermeable membrane nanofiltration cycle. After the salt concentration increases, the solution is diluted again and subjected to a second-stage semipermeable membrane nanofiltration cycle. Finally, the solution is concentrated and crystallized to produce betaine. This method requires continuous addition of water to dilute the salt-containing solution. Furthermore, betaine, with a molecular weight of 117 Da, permeates the nanofiltration membrane, resulting in a low product yield and significant betaine loss.

[0007] Although some existing technologies use methods such as electrodialysis to improve separation purity, these methods are expensive and have a small separation capacity, making them suitable for small-scale purification rather than large-scale industrial separation and purification. Therefore, the existing technologies lack a purification method for pharmaceutical-grade anhydrous betaine that requires low industrial investment and produces high product purity.

[0008] In addition, membrane separation technology, as a physical separation process, is widely used for the desalination and concentration of compounds due to its characteristics such as no phase change, low energy consumption, and simple operation. For example, the published patent CN113461663A discloses a membrane separation and purification method for the proton pump inhibitor esomeprazole sodium. The method uses an ultrafiltration membrane to remove large particulate impurities in the aqueous solution, and then uses a nanofiltration membrane to separate esomeprazole sodium and potassium dihydrogen phosphate / dipotassium hydrogen phosphate after adjusting the pH value with sodium hydroxide. This method utilizes the nanofiltration membrane's ability to retain high-valent salts. Although it can remove most trivalent inorganic salts, since potassium dihydrogen phosphate / dipotassium hydrogen phosphate are both water-soluble salts, the removal effect is poor when the content of potassium dihydrogen phosphate / dipotassium hydrogen phosphate in the aqueous solution is high, reaching only about 71%. This method also cannot meet the needs of large-scale production of pharmaceutical-grade anhydrous betaine. Summary of the Invention

[0009] The purpose of the present invention is to provide a method for preparing anhydrous betaine for medicinal use, in view of the defects of the existing betaine purification method, such as high production cost and unsuitability for large-scale industrial application.

[0010] To achieve the above object, the present invention adopts the following technical solutions:

[0011] The present invention provides a method for preparing anhydrous betaine for medicinal use, comprising the following steps:

[0012] (1) Preparation of betaine reaction crude liquid: betaine reaction crude liquid is prepared by beet molasses, beet molasses yeast fermentation wastewater, or by calcium method or sodium method, and set aside;

[0013] (2) Column chromatography: The crude betaine reaction solution is adsorbed on a cation exchange resin and eluted with 0.5-2% phosphoric acid, and the eluted fraction containing betaine is collected;

[0014] (3) Desalination: The eluted fraction is adjusted to a pH of 6.5-7.5 with a calcium hydroxide aqueous solution to fully convert betaine into free base. The insoluble phosphate is removed by filtration and the filtrate is collected. The filtrate is first filtered with a nanofiltration membrane to intercept a small amount of high-valent salt dissolved in the filtrate, and the permeate is collected. The filtrate is then concentrated with a reverse osmosis membrane and the circulating liquid is collected.

[0015] (4) Crystallization and drying: Filter the circulating liquid and transfer it into a crystallization kettle. Add acetone while stirring, cool and crystallize. Centrifuge to separate the solid material, dry it, crush it, and sieve it to obtain pure anhydrous betaine.

[0016] Preferably, in step (1), the betaine reaction crude solution is synthesized by the calcium method, and the synthesis process is:

[0017] Dissolve chloroacetic acid in purified distilled water, add calcium hydroxide suspension to neutralize, then add trimethylamine aqueous solution to react, cool, and obtain a betaine reaction crude solution.

[0018] Preferably, in step (1), the betaine reaction crude solution is synthesized by the calcium method, and the synthesis process is:

[0019] Chloroacetic acid was added to a reactor, dissolved in purified distilled water, and then the calcium hydroxide suspension was added to neutralize to a pH of 7.0-8.0. A 30% aqueous solution of trimethylamine was slowly added under stirring, and then heated to 55°C-65°C for 4 hours and cooled to obtain a crude betaine reaction solution.

[0020] Preferably, in step (2), the cation exchange resin is a strong acid cation exchange resin such as cation exchange resin 001×7 (732), 001×8, 001×10, 001×14.5 or D001.

[0021] Preferably, in step (2), the cation exchange resin is pretreated before use:

[0022] Take a cation exchange resin and soak it in 2 times the volume of saturated sodium chloride aqueous solution overnight. Filter the soaking liquid until the outflowing solution is colorless and then load it into the column with purified water;

[0023] After column loading, wash the resin with 4 column volumes of 4% NaOH aqueous solution and continue soaking for 2 hours. Filter out the NaOH aqueous solution and wash with purified water until it is nearly neutral.

[0024] The resin was then washed with 4 column volumes of 1N HCl aqueous solution and soaked for another 2 hours. The HCl aqueous solution was filtered off and the resin was washed with purified water until it was nearly neutral.

[0025] Preferably, in step (2), the specific method of column chromatography is:

[0026] The crude betaine reaction solution obtained in step (1) was loaded onto the pretreated cation exchange resin at a rate of 4 column volumes / hr. After loading, the column was rinsed with 3 column volumes of purified water, and then eluted with a 0.5-2% aqueous phosphoric acid solution at a rate of 5 column volumes / hr, and the eluted fractions were collected.

[0027] More preferably, in step (2), the concentration of the phosphoric acid aqueous solution is 1-2%.

[0028] Preferably, in step (2), before collecting the fractions, each collected fraction is detected by HPLC, and only the fractions containing the target component are combined.

[0029] Preferably, in step (3), the molecular weight cut-off of the nanofiltration membrane is 150 to 800 Da.

[0030] Preferably, in step (3), when collecting the permeate, a small amount of purified water is added after the circulating liquid volume is reduced to 1 / 5 of the original volume to ensure that the betaine passes through the nanofiltration membrane.

[0031] Preferably, in step (3), the circulating liquid is collected until the volume of the circulating liquid is 1 / 5 to 1 / 10 of the volume of the original filtrate.

[0032] More preferably, in step (3), the circulating liquid is collected until the volume of the circulating liquid is 1 / 8 to 1 / 9 of the volume of the original filtrate.

[0033] Preferably, in step (4), the crystallization temperature is 4-15° C., and the crystallization time is 10-60 min; the drying is carried out in a vacuum drying oven, the drying temperature is 55-65° C., and the drying time is 3-8 hr.

[0034] More preferably, in step (5), the crystallization temperature is 6-8°C, and the crystallization time is 20-40 min; the drying is carried out in a vacuum drying oven, the drying temperature is 58-60°C, and the drying time is 4-6 hr.

[0035] Preferably, in step (4), the purity of the anhydrous betaine obtained after the crystallization and drying is above 99.8%, and the inorganic salt content is less than 0.05%, meeting the pharmaceutical requirements.

[0036] The present invention adopts the above technical solution, which has the following technical effects compared with the prior art:

[0037] (1) The process of the present invention obtains high-purity, low-ashness pharmaceutical-grade anhydrous betaine through calcium synthesis, cation exchange resin chromatography, nanofiltration membrane desalination, reverse osmosis membrane concentration, low-temperature crystallization with an organic solvent, and vacuum drying. The purification process is simple, the temperature conditions are mild, the separation volume is large, and the purity is high. While saving costs, it is more suitable for industrial large-scale separation and purification applications.

[0038] (2) The cation exchange resin is eluted with phosphoric acid, and the pH of the eluate is adjusted to 6.5-7.5 with calcium hydroxide to ensure that the product is fully free. The low solubility of calcium phosphate and its high-valent salt properties are utilized to perform primary desalination by precipitation, and then a small amount of residual dissolved salt in the solution is removed by nanofiltration membrane, ensuring that the inorganic salt content in the product is less than 0.1%, meeting the requirements for pharmaceutical use;

[0039] (3) After a small amount of high-valent salt dissolved in the filtrate is first filtered and intercepted by a nanofiltration membrane, the circulating liquid is concentrated and collected by a reverse osmosis membrane. Since the pore size of the reverse osmosis membrane is as small as nanometers, except for water molecules that can pass through the membrane, other solutes in the water are almost all rejected outside the membrane. Therefore, the use of the reverse osmosis membrane to concentrate the filtrate has the characteristics of high concentration efficiency and low energy consumption compared with the existing vacuum decompression concentration ratio;

[0040] (4) The process of the present invention can produce anhydrous betaine with a purity of more than 99.8%, whose X-ray diffraction spectrum is completely consistent with the United States Pharmacopoeia standard, and the crystal form meets the requirements for pharmaceutical use; at the same time, the process eliminates the original high-temperature vacuum decompression concentration and instead uses a more gentle reverse osmosis membrane for sample concentration, which saves costs while the low temperature is also more conducive to product quality control, and the QbD concept is integrated into the drug research and development and production process. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 Schematic diagram of the process for preparing the medicinal anhydrous betaine of the present invention;

[0042] Figure 2 This is the HPLC spectrum of anhydrous betaine obtained in Example 1 of the present invention;

[0043] Figure 3 This is the X-ray diffraction spectrum of anhydrous betaine obtained in Example 1 of the present invention;

[0044] Figure 4 This is the X-ray diffraction spectrum of the United States Pharmacopoeia Betaine Anhydrous standard. DETAILED DESCRIPTION

[0045] The present invention will be described in detail and specifically below through specific examples to provide a better understanding of the present invention, but the following examples do not limit the scope of the present invention.

[0046] Example 1

[0047] A preparation method of medicinal anhydrous betaine, such as Figure 1 As shown, the specific steps include:

[0048] (1) Preparation of betaine reaction crude solution: Chloroacetic acid was added to a reactor, dissolved in purified distilled water, and then calcium hydroxide suspension was added to neutralize to a pH of 7.0; 30% trimethylamine aqueous solution was slowly added under stirring, heated to 60°C for 4 hours, and cooled to obtain a betaine reaction crude solution.

[0049] (2) Pretreatment of cation exchange resin: Take cation exchange resin 001×8 and soak it in 2 volumes of saturated sodium chloride aqueous solution overnight. Filter out the soaking liquid until the outflowing solution is colorless and then load it into a column with purified water. After loading into the column, wash the resin with 4 column volumes of 4% NaOH aqueous solution and continue soaking for 2 hours. Filter out the NaOH aqueous solution and wash it with purified water until it is nearly neutral. Then wash the resin with 4 column volumes of 1N HCl aqueous solution and continue soaking for 2 hours. Filter out the HCl aqueous solution and wash it with purified water until it is nearly neutral and set aside.

[0050] (3) Column chromatography: Take the crude betaine reaction solution and load it at a rate of 4 column volumes / hr; after loading, rinse the column with 3 column volumes of purified water, then elute with 1% phosphoric acid aqueous solution at a rate of 5 column volumes / hr, and collect the eluted fractions.

[0051] (4) Desalting: HPLC was used to detect the collected fractions, and the fractions containing the target component were combined. The pH value was adjusted to 7.0 with a calcium hydroxide aqueous solution, and a small amount of precipitate was removed by filtration. The filtrate was filtered through a nanofiltration membrane (molecular weight cutoff 150 Da), and the permeate was collected. Purified water was added to wash the circulating liquid to ensure that the betaine passed through the nanofiltration membrane. At the same time, the permeate was filtered through a reverse osmosis membrane, and the circulating liquid was collected until the volume of the circulating liquid was 1 / 5 to 1 / 10 of the original filtrate volume.

[0052] (5) Crystallization and drying: Filter the circulating liquid, transfer the filtrate into a crystallization kettle, add acetone under stirring, cool to 6-8°C for crystallization for 30 minutes, centrifuge to separate the solid material, and dry it in a vacuum drying oven at 60°C for 4 hours. Grind and sieve to obtain pure anhydrous betaine.

[0053] Example 2

[0054] A preparation method of medicinal anhydrous betaine, such as Figure 1 As shown, the specific steps include:

[0055] (1) Preparation of betaine reaction crude solution: Chloroacetic acid was added to a reactor, dissolved in purified distilled water, and then calcium hydroxide suspension was added to neutralize to a pH of 7.0; 30% trimethylamine aqueous solution was slowly added under stirring, heated to 60°C for 4 hours, and cooled to obtain a betaine reaction crude solution.

[0056] (2) Pretreatment of cation exchange resin: Take cation exchange resin 001×8 and soak it in 2 volumes of saturated sodium chloride aqueous solution overnight. Filter out the soaking liquid until the outflowing solution is colorless and then load it into a column with purified water. After loading into the column, wash the resin with 4 column volumes of 4% NaOH aqueous solution and continue soaking for 2 hours. Filter out the NaOH aqueous solution and wash it with purified water until it is nearly neutral. Then wash the resin with 4 column volumes of 1N HCl aqueous solution and continue soaking for 2 hours. Filter out the HCl aqueous solution and wash it with purified water until it is nearly neutral and set aside.

[0057] (3) Column chromatography: Take the crude betaine reaction solution and load it at a rate of 4 column volumes / hr; after loading, rinse the column with 3 column volumes of purified water, elute with 2% phosphoric acid aqueous solution at a rate of 5 column volumes / hr, and collect the eluted fractions.

[0058] (4) Desalting: HPLC was used to detect the collected fractions, and the fractions containing the target component were combined. The pH value was adjusted to 7.0 with a calcium hydroxide aqueous solution, and a small amount of precipitate was removed by filtration. The filtrate was filtered through a nanofiltration membrane (molecular weight cutoff 300 Da), and the permeate was collected. Purified water was added to wash the circulating liquid to ensure that the betaine passed through the nanofiltration membrane. At the same time, the permeate was filtered through a reverse osmosis membrane, and the circulating liquid was collected until the volume of the circulating liquid was 1 / 5 to 1 / 10 of the original filtrate volume.

[0059] (5) Crystallization and drying: Filter the circulating liquid. Transfer the filtrate to a crystallization kettle, add acetone while stirring, cool to 6-8°C and crystallize for 30 minutes. Centrifuge to separate the solid material and dry it in a vacuum drying oven at 60°C for 4 hours. Grind and sieve to obtain pure anhydrous betaine.

[0060] Example 3

[0061] A preparation method of medicinal anhydrous betaine, such as Figure 1 As shown, the specific steps include:

[0062] (1) Preparation of betaine reaction crude solution: Chloroacetic acid was added to a reactor, dissolved in purified distilled water, and then calcium hydroxide suspension was added to neutralize to a pH of 7.0; 30% trimethylamine aqueous solution was slowly added under stirring, heated to 60°C for 4 hours, and cooled to obtain a betaine reaction crude solution.

[0063] (2) Pretreatment of cation exchange resin: Take cation exchange resin 732 and soak it in 2 volumes of saturated sodium chloride aqueous solution overnight. Filter out the soaking liquid until the outflowing solution is colorless and then load it into a column with purified water. After loading into the column, wash the resin with 4 column volumes of 4% NaOH aqueous solution and continue soaking for 2 hours. Filter out the NaOH aqueous solution and wash it with purified water until it is nearly neutral. Then wash the resin with 4 column volumes of 1N HCl aqueous solution and continue soaking for 2 hours. Filter out the HCl aqueous solution and wash it with purified water until it is nearly neutral and set aside.

[0064] (3) Column chromatography: The crude betaine reaction solution was loaded at a rate of 4 column volumes / hr. After loading, the column was rinsed with 3 column volumes of purified water and eluted with 1% aqueous phosphoric acid at a rate of 5 column volumes / hr. The eluted fractions were collected.

[0065] (4) Desalting: HPLC was used to detect the collected fractions, and the fractions containing the target component were combined. The pH value was adjusted to 7.0 with a calcium hydroxide aqueous solution, and a small amount of precipitate was removed by filtration. The filtrate was filtered through a nanofiltration membrane (molecular weight cutoff 300 Da), and the permeate was collected. Purified water was added to wash the circulating liquid to ensure that the betaine passed through the nanofiltration membrane. At the same time, the permeate was filtered through a reverse osmosis membrane, and the circulating liquid was collected until the volume of the circulating liquid was 1 / 5 to 1 / 10 of the original filtrate volume.

[0066] (5) Crystallization and drying: Filter the circulating liquid, transfer the filtrate into a crystallization kettle, add acetone under stirring, cool to 6-8°C for crystallization for 30 minutes, separate the solid material by centrifugation, and dry it in a vacuum drying oven at 60°C for 4 hours, crush and sieve to obtain pure anhydrous betaine.

[0067] Example 4

[0068] A preparation method of medicinal anhydrous betaine, such as Figure 1 As shown, the specific steps include:

[0069] (1) Preparation of betaine reaction crude solution: Chloroacetic acid was added to a reactor, dissolved in purified distilled water, and then calcium hydroxide suspension was added to neutralize to a pH of 7.0; 30% trimethylamine aqueous solution was slowly added under stirring, heated to 60°C for 4 hours, and cooled to obtain a betaine reaction crude solution.

[0070] (2) Pretreatment of cation exchange resin: Take cation exchange resin 001×8 and soak it in 2 volumes of saturated sodium chloride aqueous solution overnight. Filter out the soaking liquid until the outflowing solution is colorless and then load it into a column with purified water. After loading into the column, wash the resin with 4 column volumes of 4% NaOH aqueous solution and continue soaking for 2 hours. Filter out the NaOH aqueous solution and wash it with purified water until it is nearly neutral. Then wash the resin with 4 column volumes of 1N HCl aqueous solution and continue soaking for 2 hours. Filter out the HCl aqueous solution and wash it with purified water until it is nearly neutral and set aside.

[0071] (3) Column chromatography: The crude betaine reaction solution was loaded at a rate of 4 column volumes / hr. After loading, the column was rinsed with 3 column volumes of purified water and eluted with 1% aqueous phosphoric acid at a rate of 5 column volumes / hr. The eluted fractions were collected.

[0072] (4) Desalting: HPLC was used to detect the collected fractions, and the fractions containing the target component were combined. The pH value was adjusted to 7.0 with a calcium hydroxide aqueous solution, and a small amount of precipitate was removed by filtration. The filtrate was filtered through a nanofiltration membrane (molecular weight cutoff 800 Da), the permeate was collected, and purified water was added to wash the circulating liquid to ensure that the betaine passed through the nanofiltration membrane; at the same time, the permeate was filtered through a reverse osmosis membrane, and the circulating liquid was collected until the volume of the circulating liquid was 1 / 5 to 1 / 10 of the original filtrate volume.

[0073] (5) Crystallization and drying: Filter the circulating liquid, transfer the filtrate into a crystallization kettle, add acetone under stirring, cool to 6-8°C for crystallization for 30 minutes, separate the solid material by centrifugation, and dry it in a vacuum drying oven at 60°C for 4 hours, crush and sieve to obtain pure anhydrous betaine.

[0074] Comparative Example 1

[0075] A method for preparing anhydrous betaine specifically comprises the following steps:

[0076] (1) Preparation of betaine reaction crude solution: Chloroacetic acid was added to a reactor, dissolved in purified distilled water, and then calcium hydroxide suspension was added to neutralize to a pH of 7.0; 30% trimethylamine aqueous solution was slowly added under stirring, heated to 60°C for 4 hours, and cooled to obtain a betaine reaction crude solution.

[0077] (2) Pretreatment of cation exchange resin: Take cation exchange resin 001×8 and soak it in 2 volumes of saturated sodium chloride aqueous solution overnight. Filter out the soaking liquid until the outflowing solution is colorless and then load it into a column with purified water. After loading into the column, wash the resin with 4 column volumes of 4% NaOH aqueous solution and continue soaking for 2 hours. Filter out the NaOH aqueous solution and wash it with purified water until it is nearly neutral. Then wash the resin with 4 column volumes of 1N HCl aqueous solution and continue soaking for 2 hours. Filter out the HCl aqueous solution and wash it with purified water until it is nearly neutral and set aside.

[0078] (3) Column chromatography: The crude betaine reaction solution was loaded at a rate of 4 column volumes / hr. After loading, the column was rinsed with 3 column volumes of purified water, and then eluted with 1% ammonia aqueous solution at a rate of 5 column volumes / hr. The eluted fractions were collected.

[0079] (4) Concentration: HPLC was used to detect the collected fractions, and the fractions containing the target component were combined and transferred to a concentration kettle. The fractions were concentrated in vacuo at 80°C to 1 / 5 of the original volume, and the concentrate was collected.

[0080] (5) Crystallization and drying: Filter the concentrated solution. Transfer the filtrate to a crystallization kettle, add acetone while stirring, cool to 6-8°C and crystallize for 30 minutes. Centrifuge to separate the solid material and dry it in a vacuum drying oven at 60°C for 4 hours. Grind and sieve to obtain pure anhydrous betaine.

[0081] Comparative Example 2

[0082] Unlike Example 1, the nanofiltration desalination step was omitted. After obtaining the chromatographic solution by column chromatography, the pH value was adjusted to 7.0 with calcium hydroxide and the solution was directly filtered through a reverse osmosis membrane. The circulating solution was collected until the volume of the circulating solution was 1 / 5 to 1 / 10 of the original chromatographic solution volume. The circulating solution was transferred to a crystallization kettle, acetone was added with stirring, and the temperature was lowered to 6 to 8°C for 30 minutes. The solid material was separated by centrifugation and dried in a vacuum drying oven at 60°C for 4 hours. It was then crushed and sieved to obtain pure anhydrous betaine.

[0083] Comparative Example 3

[0084] The difference from Example 1 is that the step of "calcium hydroxide adjusting the pH value of the chromatographic fluid" is eliminated. After the chromatographic fluid is obtained by column chromatography, the collected fractions are detected by HPLC, and the fractions containing the target component are combined. Without filtering, the combined fractions are directly filtered through a nanofiltration membrane (molecular weight cutoff 800Da), the permeate is collected, and purified water is added to wash the circulating fluid to ensure that the betaine passes through the nanofiltration membrane; the permeate is filtered through a reverse osmosis membrane, and the circulating fluid is collected until the volume of the circulating fluid is 1 / 5 to 1 / 10 of the original chromatographic fluid volume. The circulating fluid is transferred to a crystallization kettle, acetone is added under stirring, and the temperature is lowered to 6 to 8°C for crystallization for 30 minutes. After the solid material is separated by centrifugation, it is dried in a vacuum drying oven at 60°C for 4 hours, crushed, and sieved to obtain pure anhydrous betaine.

[0085] In addition, the methods for HPLC detection and analysis of each fraction in the above embodiments and comparative examples are as follows:

[0086] Analytical column: Ultimate HILIC Amide, size 250 × 4.6 mm, particle size 5 μm.

[0087] Mobile phase: A—0.05% phosphoric acid + 0.1% triethylamine aqueous solution, B—acetonitrile.

[0088] The elution gradient is shown in Table 1 below.

[0089] Table 1 Elution gradient data of each HPLC fraction detected in each embodiment and comparative example

[0090] Time(min) A％ B％ 0 20 80 25 20 80 25.1 90 10 35 90 10 35.1 20 80 50 20 80

[0091] Note: Detection conditions: injection volume: 10 μL, column temperature: 40°C, flow rate: 1 mL / min. Detection wavelength: 195 nm.

[0092] Experimental verification

[0093] The pure anhydrous betaine prepared in Example 1 was subjected to HPLC detection and X-ray diffraction analysis, and the HPLC spectrum of the anhydrous betaine was as follows: Figure 2As shown, the X-ray diffraction spectrum of the anhydrous betaine is as shown Figure 3 shown. Figure 4 This is the X-ray diffraction spectrum of the United States Pharmacopoeia Betaine Anhydrous standard.

[0094] The detection spectrum shows that the process of the present invention can produce anhydrous betaine with a high purity of more than 99.8%, the X-ray diffraction spectrum of which is completely consistent with the United States Pharmacopoeia standard, and the crystal form meets the requirements for pharmaceutical use.

[0095] In addition, the purity, content, yield, ash content, etc. of the pure anhydrous betaine obtained in Examples 1 to 4 and Comparative Examples 1 to 3 were tested, and the test data are shown in Table 2 below.

[0096] Table 2: Experimental data of various embodiments and comparative examples

[0097]

[0098]

[0099] As can be seen from the data in Table 2 above, compared with the prior art comparative example 1, which uses strong acid ion exchange resin adsorption and dilute ammonia desorption, and then concentrates and crystallizes, the product purity is 98.7% and the ash content is 1.2%. There are problems of low purity and excessive ash content, and the product has the risk of incomplete freeness. The anhydrous betaine prepared by the process of the present invention has a purity of more than 99.8% and an ash content of less than 0.05%, meeting the requirements for pharmaceutical use, and a yield of more than 90%. While saving costs, it is suitable for industrial large-scale separation and purification applications.

[0100] It can be seen from the data in Table 2 above that, compared with Examples 1 to 4, after the "nanofiltration desalination" step is eliminated, the product purity of Comparative Example 2 is 98.9%, and the ash content is significantly increased by 0.9%. This shows that the scheme of first using nanofiltration desalination and then reverse osmosis concentration in the present invention can effectively reduce the ash content of the product and improve the product purity.

[0101] As can be seen from the data in Table 2 above, compared with Examples 1 to 4, after canceling the step of "calcium hydroxide adjusting the pH value of the chromatography fluid", the product purity of Comparative Example 3 is 99.2%, the product pH value is 5.04, and the ash content is significantly increased by 0.5%. This is because the pH value is not adjusted, so that phosphoric acid dissolves in the sample, reducing the interception ability of the nanofiltration membrane for high-valent salts, making the ash content substandard, and there is a risk of incomplete product freeing. This shows that the present invention first adjusts the pH value of the sample solution to neutrality so that the sample is completely free, and then adopts the scheme of nanofiltration desalination to effectively reduce the ash content of the product and improve product purity.

[0102] While the specific embodiments of the present invention have been described in detail above, these are merely exemplary and the present invention is not limited thereto. For those skilled in the art, any equivalent modifications and substitutions to the present invention are also within the scope of the present invention. Therefore, any equivalent changes and modifications made without departing from the spirit and scope of the present invention are intended to be encompassed within the scope of the present invention.

Claims

1. A method for preparing anhydrous betaine for medicinal use, characterized in that: The steps include: (1) Preparation of betaine reaction crude liquid: betaine reaction crude liquid is prepared by beet molasses, beet molasses yeast fermentation wastewater, or by calcium method or sodium method, and set aside; (2) Column chromatography: The crude betaine reaction solution is adsorbed on a cation exchange resin and eluted with 0.5-2% phosphoric acid, and the eluted fraction containing betaine is collected; (3) Desalting: The eluted fraction is adjusted to a pH of 6.5-7.5 with a calcium hydroxide aqueous solution to fully convert betaine into free base. The insoluble phosphate is removed by filtration, and the filtrate is collected; First, a small amount of high-valent salt dissolved in the filtrate is filtered and intercepted by a nanofiltration membrane, and the permeate is collected; then, the reverse osmosis membrane is used to concentrate and the circulating liquid is collected; (4) Crystallization and drying: Filter the circulating liquid and transfer it into a crystallization kettle. Add acetone while stirring, cool and crystallize. Centrifuge to separate the solid material, dry it, crush it, and sieve it to obtain pure anhydrous betaine.

2. The preparation method according to claim 1, characterized in that In step (1), the betaine reaction crude solution is synthesized by the calcium method, and the synthesis process is: Dissolve chloroacetic acid in purified distilled water, add calcium hydroxide suspension to neutralize, then add trimethylamine aqueous solution to react, cool, and obtain a betaine reaction crude solution.

3. The preparation method according to claim 1, characterized in that In step (2), the cation exchange resin is 001×7, 001×8, 001×10, 001×14.5 or D001 strongly acidic cation exchange resin.

4. The preparation method according to claim 1, characterized in that In step (2), the cation exchange resin is pretreated before use: Take a cation exchange resin and soak it in 2 times the volume of saturated sodium chloride aqueous solution overnight. Filter the soaking liquid until the outflowing solution is colorless and then load it into the column with purified water; After column loading, wash the resin with 4 column volumes of 4% NaOH aqueous solution and continue soaking for 2 hours. Filter out the NaOH aqueous solution and wash with purified water until it is nearly neutral. The resin was then washed with 4 column volumes of 1N HCl aqueous solution and soaked for another 2 hours. The HCl aqueous solution was filtered off and the resin was washed with purified water until it was nearly neutral.

5. The preparation method according to claim 1, characterized in that In step (2), the specific method of column chromatography is: The crude betaine reaction solution obtained in step (1) was loaded onto the pretreated cation exchange resin at a rate of 4 column volumes / hr. After loading, the column was rinsed with 3 column volumes of purified water, and then eluted with a 0.5-2% aqueous phosphoric acid solution at a rate of 5 column volumes / hr, and the eluted fractions were collected.

6. The preparation method according to claim 1, characterized in that In step (3), the molecular weight cut-off of the nanofiltration membrane is 150 to 800 Da.

7. The preparation method according to claim 1, characterized in that In step (3), when collecting the permeate, a small amount of purified water is added after the circulating liquid volume is reduced to 1 / 5 of the original volume to ensure that the betaine passes through the nanofiltration membrane.

8. The preparation method according to claim 1, characterized in that In step (3), the circulating liquid is collected until the volume of the circulating liquid is 1 / 5 to 1 / 10 of the original filtrate volume.

9. The preparation method according to claim 1, characterized in that In step (4), the crystallization temperature is 4-15° C., and the crystallization time is 10-60 min; the drying is carried out in a vacuum drying oven, the drying temperature is 55-65° C., and the drying time is 3-8 hr.

10. The preparation method according to claim 1, characterized in that In step (4), the purity of the anhydrous betaine obtained after crystallization and drying is above 99.8%, and the inorganic salt content is lower than 0.05%, which meets the requirements for pharmaceutical use.

Images