Preparation method of seleninic acid

Abstract

As the human body cannot prepare selenium, almost all selenium in the human body comes from diet. The main food for providing selenium in the diet is bread, grains, meat, fish, eggs, dairy products and the like. However, the selenium element which can be absorbed and utilized by the human body in the diet is limited. Therefore, the seleninic acid plays an important role in providing trace elements necessary for the human body as a medicine supplement. The invention discloses a preparation method of seleninic acid, and belongs to the technical field of medicines, and the seleninic acid is used as a medicine supplement. The seleninic acid conforming to the United States Pharmacopoeia standard is obtained through crude product preparation, decoloration and refining. The method has the beneficial effects that the method has the advantages of simple preparation route, mild reaction conditions, convenience in operation, low cost, small environmental pollution and high yield, and is suitable for industrial large-scale production.

Description

Technical Field

[0001] The invention belongs to the technical field of medicine, and particularly relates to a method for preparing selenious acid. Background Art

[0002] Selenous acid is known in English as Selenous acid, has a molecular formula of H2O3Se, a molecular weight of 128.97400, and a CAS registration number of 7783-00-8. It occurs as colorless or white hexagonal prism-shaped crystals. Its structural formula is shown in Formula I.

[0003] (Formula I).

[0004] Selenous acid (Selenous acid) is a pharmaceutical supplement and an essential trace element closely related to human health. Selenium deficiency can weaken the immune system and increase the incidence of cancer, cardiovascular disease, and liver disease. Long-term, severe selenium deficiency can also lead to endemic diseases such as Keshan disease and Kashin-Beck disease. In animal models, selenium has been shown to protect the kidneys from oxidative stress and immune defenses. Selenium plays an important role in the prevention and treatment of cancer, enhancing the body's immune and antioxidant capacity and inhibiting cancer cell division, growth, and DNA synthesis. Selenium supplements can also serve as an adjunct therapy during radiotherapy or chemotherapy. Because the human body cannot synthesize selenium, almost all of its selenium comes from the diet. The main dietary sources of selenium include bread, cereals, meat, fish, eggs, and dairy products. However, the amount of selenium that can be absorbed and utilized by the human body is limited. Therefore, selenous acid, as a pharmaceutical supplement, plays a crucial role in providing essential trace elements to the human body.

[0005] Currently, the preparation methods of selenious acid can be divided into the following two categories according to the different starting materials: preparation methods using elemental selenium as the starting material and preparation methods using selenium dioxide as the starting material.

[0006] Literature reports a preparation method using elemental selenium as the starting material. At room temperature, nitric acid (density 1.18) is reacted with selenium until nitrogen oxides cease to escape. The mixture is then evaporated to dryness at 50-60°C. The resulting solid is dissolved in water and filtered. The filtrate is evaporated and concentrated to 1 / 4 of its original volume, then cooled and crystallized. The resulting crystals are filtered with suction and washed with a small amount of ice water. The washing liquid and filtrate are combined and recycled, and the resulting crystals are recrystallized using the above method to obtain the reagent selenious acid. This method uses a strong acid and produces nitrogen oxides with a pungent odor and environmental pollution during the reaction. The process is cumbersome and complex, making it unsuitable for scale-up industrial production.

[0007] Literature reports a preparation method using selenium dioxide as the starting material. Pure SeO2 is dissolved in a small amount of water, and the solution is evaporated and concentrated on a water bath until crystals begin to precipitate (dust should be avoided during the operation, otherwise it will be reduced to Se). After cooling, the precipitated selenous acid crystals are filtered using a glass frit funnel, then recrystallized once with water and dried. The product is placed between two layers of filter paper and squeezed hard, then placed in a vacuum desiccator filled with KOH for several days to dry. If concentrated sulfuric acid or phosphorus pentoxide is used as a desiccant, prolonged storage may cause further dehydration to become selenium dioxide. This method can prepare a small amount of selenous acid, but long-term high-temperature distillation will cause some of the selenous acid to decompose, and the operation is complicated during the scale-up production process. Summary of the Invention

[0008] The present invention discloses a method for preparing selenious acid, which is characterized in that the structural formula of the selenious acid is as follows.

[0009] .

[0010] The present invention is achieved through the following technical scheme: a preparation method of selenious acid, which comprises the following steps.

[0011] S1. Crude Product Preparation: Add purified water to a reaction vessel, control the reaction temperature to 50±60°C, add selenium dioxide, raise the temperature to 75-85°C, and maintain the reaction for 2-4 hours. Filter while hot. Cool the filtrate at 10°C / hour to 40-45°C and stir at this temperature for 3 hours. Once a large amount of solid precipitates, continue cooling to 0-10°C, stir at this temperature for 1 hour, and filter. Dry the wet product at room temperature at -0.09 MPa for approximately 3-5 hours, turning the mixture over every 2 hours. Collect the crude selenious acid.

[0012] S2. Decolorization and Refining: Add purified water to a reactor and control the reaction temperature to 50±60°C. Add the crude selenious acid and stir until dissolved. Add pharmaceutical activated carbon and raise the temperature to 75-85°C. Maintain stirring for approximately 2 hours. Filter while hot. Cool the filtrate to 40-45°C and stir for 3 hours. Once a large amount of solid precipitates, continue cooling to 0-10°C, maintain stirring for 1 hour, and filter. Dry the wet product at room temperature at -0.09 MPa for approximately 3-5 hours, turning the mixture over every 2 hours. Collect the selenious acid.

[0013] The preparation route is as follows: .

[0014] Furthermore, the preparation method of selenious acid is characterized in that the mass ratio of selenium dioxide and purified water in step S1 is 1:3-5, the reaction is carried out at 75-85°C for 2-4 hours, after hot filtration, the temperature is gradually reduced to 40-45°C, the temperature is kept and stirred for 3 hours, and after gradient cooling, the crude selenious acid is filtered to obtain.

[0015] Furthermore, the method for preparing selenious acid is characterized in that the mass ratio of the crude selenious acid, purified water, and medicinal activated carbon in step S2 is 1:3-5:2%-5%. The reaction is carried out at 75-85°C for 2-4 hours, followed by hot filtration, followed by gradual cooling to 40-45°C, stirring at this temperature for 3 hours, and then filtering to obtain selenious acid.

[0016] Furthermore, the selenious acid meets the quality standards of selenious acid in the United States Pharmacopoeia.

[0017] In summary, the beneficial effects of the present invention are as follows: a method for preparing selenious acid, a pharmaceutical supplement, is disclosed. The method has the advantages of a simple preparation route, mild reaction conditions, convenient operation, low cost, low energy consumption, environmental friendliness, and high yield, and is suitable for large-scale factory production. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is the IR spectrum of selenious acid in Invention Example 1. DETAILED DESCRIPTION

[0019] The present invention will be further described below with reference to the embodiments, but the protection scope of the present invention is not limited to the following.

[0020] The present invention uses selenium dioxide as a raw material, and prepares the target product, selenious acid, by crude product preparation, decolorization and purification. The preparation route is as follows.

[0021] .

[0022] Example 1: A method for preparing selenious acid, comprising the following steps.

[0023] S1. Crude Product Preparation: Add 150g of purified water to a reaction vessel, raise the temperature to 50±60°C, add 500g of selenium dioxide, continue heating to 75-85°C, and maintain the reaction for 2 hours. Filter while hot. Cool the filtrate at 10°C / hour to 40-45°C and stir at this temperature for 3 hours. After a large amount of solid precipitates, continue cooling to 0-10°C, stir at this temperature for 1 hour, and filter. Dry the wet product at room temperature at -0.09 MPa for approximately 3-5 hours. Stir the mixture once every 2 hours during drying. 453.3g of crude selenious acid is obtained, with a yield of 78% and a content of 97.2%.

[0024] S2. Decolorization and Refining: Add 120 g of purified water to a reactor and control the reaction temperature to 50 ± 60°C. Add 400 g of crude selenious acid and stir until dissolved. Then, add 8 g of pharmaceutical-grade activated carbon. Raise the temperature to 75-85°C and stir for approximately 2 hours. Filter while hot. Cool the filtrate to 40-45°C and stir for 3 hours. After a large amount of solid precipitates, continue cooling to 0-10°C, stir for 1 hour, and filter. Dry the wet product at room temperature at -0.09 MPa for approximately 3-5 hours, turning the product every 2 hours. The product yields 334.9 g of selenious acid, with a 96.9% content and a yield of 72%. The residue on ignition is 0.001%, and selenium is 624.84 μg / mg. Physical, chemical, and elemental impurities meet the United States Pharmacopoeia standards.

[0025] Example 2: A method for preparing selenious acid, comprising the following steps.

[0026] S1. Crude Product Preparation: Add 0.6 kg of purified water to a reactor and heat to 50±60°C. Add 2 kg of selenium dioxide and heat to 75-85°C. Incubate for 2-4 hours. Filter while hot. Cool the filtrate at 10°C / hour to 40-45°C and stir for 3 hours. Once a large amount of solid precipitates, continue cooling to 0-10°C, stir for 1 hour, and filter. Dry the wet product at room temperature at -0.09 MPa for approximately 3-5 hours, turning the mixture over every 2 hours. This yields 1.88 kg of crude selenious acid, with a yield of 81%.

[0027] S2. Decolorization and purification: Add 0.54 kg of purified water to a reactor, control the reaction temperature at 50 ± 60°C, add 1.8 kg of crude selenious acid, stir until dissolved, then add 36 g of pharmaceutical activated carbon. Raise the temperature to 75-85°C and stir at this temperature for approximately 2 hours. Filter while hot. Cool the filtrate to 40-45°C and stir at this temperature for 3 hours. After a large amount of solid precipitates, continue cooling to 0-10°C, stir at this temperature for 1 hour, and filter. Dry the wet product at room temperature at -0.09 MPa for approximately 3-5 hours, turning the product once every 2 hours. The product yields 1.57 kg of selenious acid with a content of 97.5% and a yield of 75%. The residue on ignition is 0.000%, and selenium is 619.36 μg / mg. Physical, chemical, and elemental impurities meet the United States Pharmacopoeia standards.

Claims

1. A method for preparing selenious acid, characterized in that: It includes the following steps: S1. Preparation of crude product: Add purified water to the reactor, control the reaction temperature to 50±60℃, add selenium dioxide, raise the temperature to 75-85℃, and keep the reaction warm for 2-4 hours. Filter while hot. Cool the filtrate to 40-45℃ at 10℃ / h, keep warm and stir for 3 hours. After a large amount of solid precipitates, continue to cool to 0-10℃, keep warm and stir for 1 hour, and filter. Dry the wet product at room temperature at -0.09MPa for about 3-5 hours. Turn the material once every 2 hours of drying. Collect the crude selenious acid; S2. Decolorization and purification: Add purified water to the reactor, control the reaction temperature to 50±60℃, add crude selenious acid, stir until dissolved, add medicinal activated carbon, heat to 75-85℃, and stir at this temperature for about 2 hours. Filter while hot. Cool the filtrate to 40-45℃, stir at this temperature for 3 hours. After a large amount of solid precipitates, continue to cool to 0-10℃, stir at this temperature for 1 hour, and filter. Dry the wet product at room temperature at -0.09MPa for about 3-5 hours. Turn the material over once every 2 hours of drying. Collect the material to obtain selenious acid; The preparation route is as follows: .

2. The method for preparing selenious acid according to claim 1, wherein The mass ratio of selenium dioxide and purified water in step S1 is 1:3-5, and the reaction is carried out at 75-85°C for 2-4 hours. After hot filtration, the temperature is gradually reduced to 40-45°C, and the temperature is kept and stirred for 3 hours. After gradual cooling, the crude selenious acid is obtained by filtration.

3. The method for preparing selenious acid according to claim 1, wherein In step S2, the mass ratio of the crude selenious acid, purified water, and medicinal activated carbon is 1:3-5:2%-5%. The reaction is carried out at 75-85°C for 2-4 hours. After hot filtration, the temperature is gradually reduced to 40-45°C, stirred at this temperature for 3 hours, and filtered after gradual cooling to obtain selenious acid.

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