Refining method of high-purity vitamin A palmitate

Abstract

The invention discloses a refining method of high-purity vitamin A palmitate for the first time, the process can effectively control the levels of oxidation impurities, isomers and polymers in the product, and the obtained product is kept stable under conventional storage conditions. The refining method comprises the following steps: dissolving a vitamin A palmitate crude product in a solvent, adding acetonitrile and an antioxidant, heating to dissolve, cooling to crystallize, and filtering; and transferring a filter cake to a reaction kettle, adding a solvent, supplementing an antioxidant, and concentrating to obtain a high-purity vitamin A palmitate finished product. The refining method of the high-purity vitamin A palmitate is suitable for large-scale production, and the product stability is good.

Description

Technical Field

[0001] The present invention belongs to the field of pharmaceutical chemical synthesis technology, and specifically relates to a method for refining high-purity vitamin A palmitate. Background Art

[0002] The structural formula of vitamin A palmitate is as follows:

[0003]

[0004] In the pharmacopoeia, retinol, vitamin A acetate, and vitamin A palmitate are collectively referred to as vitamin A. Vitamin A is a fat-soluble vitamin and one of the essential nutrients for the human body. Among them, retinol is chemically more active and is easily destroyed by acid, air, oxidants, high temperature or ultraviolet rays, while vitamin A palmitate is more stable and is widely used in food and medicine.

[0005] Vitamin A palmitate is the raw material for preparations such as Multivitamin (12) for Injection, 12-complex Vitamins for Injection, Multivitamin Injection (13) (10 / 3), Multivitamin (13) for Injection, Multivitamin Injection for Children (13), Multivitamin (13) for Injection for Children, Fat-soluble Vitamins for Injection (I), and Fat-soluble Vitamins for Injection (II).

[0006] The synthesis process of vitamin A palmitate mainly uses vitamin A acetate as the starting material, and retinol is obtained by hydrolysis, and retinol is then condensed with palmitic acid to obtain vitamin A palmitate. The starting material vitamin A acetate will produce degradation impurities such as oxidative impurities, isomers and polymers during long-term storage. In the process of producing retinol, due to the poor stability of retinol and its easy degradation, the degradation impurities of the starting material and the intermediate will be introduced into vitamin A palmitate, and vitamin A palmitate is oily, so it is difficult to develop its refining process. In particular, the oxidative impurities of vitamin A, as reported in references (Chem. Res. Toxicol. 2005, 18, 129-138. and Int J Vitam Nutr Res. 1992, 62(3),201-208.), are mostly epoxy structures, and epoxy structures are warning structures of genotoxic impurities, which have potential safety risks.

[0007] All-trans vitamin A palmitate is the most stable and effective active ingredient of vitamin A palmitate. During the production, storage and transportation process, many factors lead to the isomerization of vitamin A palmitate, thus affecting its activity and effectiveness. The biological potency of cis- and trans-isomers varies greatly. The biological activity of cis-isomers of vitamin A palmitate is lower than that of all-trans, among which the relative activity of 13-cis-isomer is 76%, the relative activity of 11-cis-isomer is 31%, the relative activity of 9-cis-isomer is 19%, and the relative activity of 9,13-bis-cis-isomer is only 16% (Yu An. Study on the Stability of Vitamin A [D]. Hangzhou: Zhejiang University, 2012.). The content of each cis-isomer impurity affects the effectiveness and safety of vitamin A palmitate API and its related preparations. Therefore, strict control of the limit of each impurity isomer can ensure the effectiveness and safety of vitamin A palmitate API and its related preparations.

[0008] In the existing literature reports, Wanhua Chemical patents CN 112724059 and CN 113122870 reported the refining of vitamin A palmitate, using alcohol solvents to crystallize the product at -2~20℃, and the main solvents used were methanol and ethanol. Due to the large difference in the polarity of the substances, it has been verified that methanol and ethanol will separate from vitamin A palmitate under low temperature conditions and cannot achieve a good refining effect. Isopropanol and the like have a certain solubility in the product. After investigation, isopropanol was used as a solvent for crystallization below 0℃. Isopropanol is easy to solvate with the product, which is difficult to filter and separate, and alcohol solvents have limited removal effects on degradation impurities such as oxidation. At the same time, it was found that solvated vitamin A palmitate is more likely to generate oxidative impurities.

[0009] CN 118812405 reports a purification method for improving the purity and content of vitamin A palmitate and reducing the residual organic solvent. The crude vitamin A palmitate is added to a ketone solvent, heated and stirred to dissolve, and then cooled and an alcohol solvent is added for crystallization to obtain vitamin A palmitate. The residual organic solvent content of the product is very low (less than 0.1%). The purification method is mainly used to reduce the residual organic solvent content of vitamin A palmitate, and the impurities in the finished vitamin A palmitate, especially the content of the cis isomer, are not limited.

[0010] CN 102424662 reports a method for separating and purifying vitamin A palmitate, wherein palmitic acid is removed by low-temperature crystallization, and vitamin A palmitate and vitamin A acetate are separated by liquid-liquid extraction separation or silica gel column chromatography separation. The method includes a column chromatography process and is not suitable for scale-up production. In addition, the method is only applicable to palmitic acid and vitamin A acetate, and is not applicable to the removal of the cis-isomer of vitamin A palmitate.

[0011] CN1072646C reports a method for purifying stable vitamin A, which limits the impurity of vitamin A cis isomer to less than 2%, thus ensuring the effectiveness and safety of vitamin A palmitate-related preparations. However, this process is only applicable to the preparation of stable vitamin A, the purity of the obtained vitamin A is not high, and the purification process requires heating and pressure control, which is complicated to operate.

[0012] Vitamin A palmitate is an oily substance, which becomes a paste after solidification and is not easy to purify. The process impurities and degradation impurities in it affect the quality and safety of the product. With the consistency evaluation of drugs, the quality control of vitamin A palmitate is becoming more and more stringent, but the existing technology does not fully define the content limit of impurities such as isomers in vitamin A palmitate, and there is a lack of relevant technology to prepare high-quality and high-purity vitamin A palmitate. Therefore, it is of great significance to develop a method for refining vitamin A palmitate to obtain high-purity and stable quality vitamin A palmitate. Summary of the invention

[0013] In order to overcome the shortcomings of the above-mentioned technology, the present invention provides a method for refining high-purity vitamin A palmitate, which can effectively control the levels of isomers, oxidative impurities and polymers in the product, and the obtained product remains stable under conventional storage conditions.

[0014] The purification method of vitamin A palmitate is as follows:

[0015] Step (1) dissolving crude vitamin A palmitate in a solvent, adding acetonitrile and an antioxidant, heating to dissolve, cooling to crystallize, and filtering.

[0016] Step (2) The filter cake is transferred to a reaction kettle, a solvent is added, an antioxidant is added, and the mixture is concentrated to obtain the finished product of vitamin A palmitate.

[0017] The above purification method is characterized in that the vitamin A palmitate dissolving solvent described in step (1) is one of acetone, ethyl acetate, and isopropanol; the dissolving solvent is 1 to 4 times the mass of vitamin A palmitate; the acetonitrile is 1 to 4 times the mass of vitamin A palmitate; and the ratio of solvent to acetonitrile is 1:0.5 to 3.

[0018] The above purification method is characterized in that the antioxidant described in step (1) is one of racemic α-tocopherol, 2,6-di-tert-butyl-4-methylphenol, and vitamin E; the amount of the antioxidant used is 0.1% to 2% of the mass of vitamin A palmitate.

[0019] The above purification method is characterized in that the dissolution temperature in step (1) is 15-40°C, preferably 20-35°C; and the crystallization temperature is -15-10°C, preferably -15-0°C.

[0020] The above refining method is characterized in that the dissolving solvent described in step (2) is one of n-heptane, n-hexane, and petroleum ether, or a combination in any proportion, and the amount used is 2 to 5 times the amount of vitamin A palmitate fed.

[0021] The above purification method is characterized in that the antioxidant described in step (2) is one of racemic α-tocopherol, 2,6-di-tert-butyl-4-methylphenol, and vitamin E; the amount of the antioxidant used is 0.9% to 2% of the mass of vitamin A palmitate.

[0022] The beneficial effects of the present invention are:

[0023] 1) The yield of vitamin A palmitate obtained by the refining process of the present invention is as high as 93%, the purity is as high as 99.38%, the cis-isomer impurity content limit is not more than 1wt%, the maximum single impurity is not more than 0.10wt%, the total impurity limit is not more than 2.0wt%, the polymer limit is not more than 0.5wt%, and the palmitic acid limit is not more than 0.5wt%, thereby ensuring the effectiveness and safety of vitamin A palmitate-related preparations.

[0024] 2) The refining process of the present invention adds antioxidants twice to further ensure the stability of the finished product of vitamin A palmitate under normal storage conditions. The accelerated stability test data of 0 days, 1 month, 2 months, 3 months, and 6 months show that the product produced by this process has good stability, the isomer impurity content limit does not exceed 1wt%, the maximum single impurity does not exceed 0.10wt%, and the polymer, isomer, and oxidized impurities grow slowly.

[0025] 3) The refining process of the present invention avoids the phenomenon of solvation produced in the refining process using alcohol solvents. The product is uniformly precipitated in the crystallization system, has strong impurity removal ability, is easy to operate, has a high yield, and is suitable for large-scale production.

[0026] 4) The refining method is simple to operate, has no special requirements for equipment, and does not involve special raw materials. It is suitable for large-scale production. The refined vitamin A palmitate meets the requirements for vitamin A palmitate raw materials for preparations such as multivitamins for injection (12), 12 complex vitamins for injection, multivitamin injection (13) (10 / 3), multivitamin for injection (13), multivitamin injection for children (13), multivitamin for injection for children (13), fat-soluble vitamins for injection (I), and fat-soluble vitamins for injection (II). BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is the HPLC spectrum of high-purity vitamin A palmitate prepared in Example 8;

[0028] Figure 2This is the peak result of the HPLC spectrum of high-purity vitamin A palmitate prepared in Example 8. DETAILED DESCRIPTION

[0029] The present invention is further described below in conjunction with specific implementation methods. The following description is only for explaining the present invention. The protection scope of the present invention is not limited to these embodiments. Those skilled in the art should understand that equivalent substitutions or corresponding improvements made to the contents of the present invention still fall within the protection scope of the present invention.

[0030] The following specific examples are provided to illustrate the present invention in detail, but are not intended to limit the present invention.

[0031] The detection method of vitamin A palmitate in this technology is as follows:

[0032] The detection method of related substances and contents of vitamin A palmitate refers to the method disclosed in patent document CN 108445098 "An analytical method for detecting impurities in vitamin A palmitate": high performance liquid chromatography, the chromatographic column is an octadecylsilane bonded silica gel chromatographic column, the mobile phase A is 5mmol / L ammonium acetate solution (adjusting the pH value to 4.5 with glacial acetic acid)-methanol, the volume ratio is 30:70, the mobile phase B is methanol-isopropanol, the volume ratio is 55:45, the detection wavelength is 325nm, the column temperature is 30℃, the flow rate is 1.0mL / min, and the mobile phases A and B are carried out according to the gradient elution program:

[0033]

[0034] The HPLC detection method for 13-cis isomer, 9,13-di-cis isomer and 9-cis isomer in vitamin A palmitate is high performance liquid chromatography, and the chromatographic conditions are: chromatographic column: octadecylsilane bonded silica gel chromatographic column; flow rate: 1.0 mL / min; detection wavelength: 325 nm; column temperature: 30°C; isocratic elution; mobile phase: n-hexane-isopropanol (999.5:0.5).

[0035] Example 1

[0036] Add 30 g crude vitamin A palmitate into a dissolving solvent and acetonitrile, and 0.08 g racemic α-tocopherol, and heat to 20°C to 35°C under nitrogen protection, stir to dissolve, and then cool to -10°C to 5°C, stir to crystallize for 1 hour, and filter.

[0037] The filter cake was dissolved in 80 mL of n-hexane, and after the solution was clear, 0.36 g of racemic α-tocopherol was added, stirred for 5 to 10 minutes, and concentrated under reduced pressure until the n-hexane content was ≤ 0.5%, and the finished product of vitamin A palmitate was obtained. The following table shows the detection and monitoring data of vitamin A palmitate prepared by each process:

[0038]

[0039] Note: The volume ratio of the dissolving solvent and acetonitrile to the mass ratio of crude vitamin A palmitate is in the range of 1~4ml:1g, expressed as 1~4V.

[0040] Example 2

[0041] Add 30 g crude vitamin A palmitate to 90 mL isopropanol and 90 mL acetonitrile, and 0.06 g 2,6-di-tert-butyl-4-methylphenol, and heat to 20°C to 35°C under nitrogen protection, stir to dissolve, then cool to -15°C to -10°C, stir to crystallize for 1 hour, and filter.

[0042] The filter cake was dissolved in 80 mL of n-heptane, and after it became clear, 0.4 g of 2,6-di-tert-butyl-4-methylphenol was added, and the mixture was stirred for 5 to 10 minutes. The mixture was concentrated under reduced pressure until the n-heptane concentration was ≤ 0.5%, and the finished product of vitamin A palmitate was obtained with a yield of 92%.

[0043] Example 3

[0044] Add 30 g crude vitamin A palmitate to 90 mL acetone and 60 mL acetonitrile, and 0.6 g vitamin E. Heat to 20°C to 35°C under nitrogen protection, stir to dissolve, cool to -5°C to 0°C after dissolving, stir to crystallize for 1 hour, and filter.

[0045] The filter cake was dissolved in 80 mL of n-heptane, and after it became clear, 0.4 g of vitamin E was added, stirred for 5 to 10 minutes, and concentrated under reduced pressure until the n-heptane concentration was ≤ 0.5%, to obtain the finished product of vitamin A palmitate with a yield of 78%.

[0046] Example 4

[0047] Add 30 g crude vitamin A palmitate to 90 mL isopropanol and 90 mL acetonitrile, and 0.04 g racemic α-tocopherol, and heat to 20°C to 35°C under nitrogen protection, stir to dissolve, then cool to -5°C to 0°C, stir to crystallize for 2 hours, and filter.

[0048] The filter cake was dissolved in 80 mL of n-heptane, and after the solution was clear, 0.5 g of racemic α-tocopherol was added, stirred for 5 to 10 minutes, and concentrated under reduced pressure until the n-heptane was ≤ 0.5%, to obtain the finished product of vitamin A palmitate with a yield of 85%.

[0049] Example 5 Accelerated stability study of the product of Example 4

[0050] The storage temperature of vitamin A palmitate is below 15°C. 20g of the product of Example 4 was placed in a soda-lime glass molded pharmaceutical bottle and accelerated for 0 days, 1 month, 3 months and 6 months in an environment with a temperature of 25°C ± 2°C and a relative humidity of 60% ± 5%. The accelerated experiment shows that the product produced by this process has good stability, the maximum single impurity does not exceed 0.10wt%, and the polymer and isomers grow slowly.

[0051]

[0052] Example 6

[0053] Add 30 g crude vitamin A palmitate to 90 mL isopropanol and 90 mL acetonitrile, and 0.04 g racemic α-tocopherol, and heat to 20°C to 35°C under nitrogen protection, stir to dissolve, then cool to -5°C to 0°C, stir to crystallize for 2 hours, and filter.

[0054] The filter cake was dissolved in 80 mL of n-heptane, and after the solution was clear, 0.27 g of racemic α-tocopherol was added, stirred for 5 to 10 minutes, and concentrated under reduced pressure until the n-heptane concentration was ≤ 0.5%, to obtain the finished product of vitamin A palmitate with a yield of 83%.

[0055] Example 7

[0056] Add 30 g crude vitamin A palmitate to 90 mL isopropanol and 90 mL acetonitrile, and 0.04 g racemic α-tocopherol, and heat to 20°C to 35°C under nitrogen protection, stir to dissolve, then cool to -5°C to 0°C, stir to crystallize for 2 hours, and filter.

[0057] The filter cake was dissolved in 80 mL of n-heptane, and after the solution was clear, 0.6 g of racemic α-tocopherol was added, stirred for 5 to 10 minutes, and concentrated under reduced pressure until the n-heptane was ≤ 0.5%, to obtain the finished product of vitamin A palmitate with a yield of 85%.

[0058] Example 8

[0059] Add 30 g crude vitamin A palmitate into a dissolving solvent and acetonitrile, and 0.08 g racemic α-tocopherol, and heat to 20°C to 35°C under nitrogen protection, stir to dissolve, and then cool to -10°C to 5°C, stir to crystallize for 1 hour, and filter.

[0060] The filter cake was dissolved in 80 mL of n-hexane, and after the solution was clear, 0.36 g of racemic α-tocopherol was added, stirred for 5 to 10 minutes, and concentrated under reduced pressure until n-hexane was ≤ 0.5%, to obtain the finished product of vitamin A palmitate with a yield of 92%. The following table shows the content data of vitamin A palmitate, 13-cis isomer, 9,13-bis-cis isomer, and 9-cis isomer in the high-purity vitamin A palmitate prepared in this example:

[0061] 。

Claims

1. A method for refining high-purity vitamin A palmitate, characterized in that: The preparation method comprises: Step 1, dissolving crude vitamin A palmitate in a solvent, adding acetonitrile and an antioxidant, heating to dissolve, cooling to crystallize, and filtering; The solvent is selected from one of acetone, ethyl acetate and isopropanol; The mass ratio of the dissolving solvent volume to vitamin A palmitate is 1-4 mL: 1 g; The mass ratio of the acetonitrile volume to vitamin A palmitate is 1-4 mL: 1 g; The volume ratio of the solvent to acetonitrile is 1:0.5-3; The amount of the antioxidant is 0.1% to 2% of the mass of vitamin A palmitate; The temperature of the heating and dissolving is 20-35°C; The cooling crystallization temperature is -15~0°C; Step 2: transferring the filter cake to a reactor, adding a solvent, adding an antioxidant, and concentrating to obtain a high-purity vitamin A palmitate product; The solvent includes one of n-heptane, n-hexane and petroleum ether or any combination thereof in any proportion; The volume ratio of the solvent to the mass ratio of vitamin A palmitate is 2-5 mL:1 g; The amount of the antioxidant is 0.9% to 2% of the mass of vitamin A palmitate; The total content of cis-isomer impurities in the impurities of the high-purity vitamin A palmitate finished product is no more than 1.0 wt %.

2. The refining method according to claim 1, characterized in that The antioxidant described in step 1 is selected from one of racemic α-tocopherol, 2,6-di-tert-butyl-4-methylphenol and vitamin E.

3. The purification method according to claim 1, characterized in that: The antioxidant described in step 2 is selected from one of racemic α-tocopherol, 2,6-di-tert-butyl-4-methylphenol and vitamin E.

4. The refining method according to claim 1, characterized in that: Step 1, dissolving crude vitamin A palmitate in a solvent, adding acetonitrile and an antioxidant, heating to dissolve, cooling to crystallize, and filtering; The solvent is one or a combination of isopropanol, acetone, and ethyl acetate, and the body ratio of the solvent to vitamin A palmitate is 3mL:1g; The mass ratio of the acetonitrile to vitamin A palmitate feed is 3 mL:1 g; The dosage of the antioxidant is 0.27% of the mass of vitamin A palmitate; Step 2: The filter cake is transferred to a reactor, a solvent is added, an antioxidant is added, and the mixture is concentrated to obtain a finished product of vitamin A palmitate; The solvent is n-hexane, and the mass ratio of the solvent to the vitamin A palmitate feed is 2.67 mL:1 g; The amount of the antioxidant used is 1.2% of the mass of vitamin A palmitate.

5. The purification method according to claim 1, characterized in that: Step 1, dissolving crude vitamin A palmitate in a solvent, adding acetonitrile and an antioxidant, heating to dissolve, cooling to crystallize, and filtering; The solvent is one or a combination of isopropanol, acetone, and ethyl acetate, and the body ratio of the solvent to vitamin A palmitate is 3mL:1g; The mass ratio of the acetonitrile to vitamin A palmitate feed is 3 mL:1 g; The dosage of the antioxidant is 2% of the mass of vitamin A palmitate feed; Step 2: The filter cake is transferred to a reactor, a solvent is added, an antioxidant is added, and the mixture is concentrated to obtain a finished product of vitamin A palmitate; The solvent is n-heptane, and the mass ratio of the solvent to the vitamin A palmitate feed is 2.67 mL: 1 g; The amount of the antioxidant used is 1.3% of the mass of vitamin A palmitate.

6. The method according to claim 1, characterized in that The cis isomer impurities in the high-purity vitamin A palmitate finished product impurities include one or more of 13-cis isomer, 9,13-di-cis isomer, and 9-cis isomer.

7. The method according to any one of claims 1 to 5, wherein the content of 13-cis isomer in the cis isomer impurities in the finished vitamin A palmitate ester is not higher than 0.5wt%, the content of 9,13-bis-cis isomer is not higher than 0.5wt%, and the content of 9-cis isomer is not higher than 0.5wt%.

8. High-purity vitamin A palmitate prepared according to any one of claims 1 to 5, characterized in that: The high-purity vitamin A palmitate has a single impurity content of no more than 0.1 wt%, a total impurity content of no more than 2.0 wt%, a polymer content of no more than 0.5 wt%, and a palmitic acid content of no more than 0.5 wt%.

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