A niobium-based solid acid catalyst and a method for preparing diosgenin

Abstract

The application discloses a niobium-based solid acid catalyst and a method for preparing diosgenin, and the method comprises the following steps: (1) extracting yellow ginger powder with alcohol solvent I by refluxing, and drying to obtain crude saponin powder; (2) in a closed reactor, reacting a mixture containing the crude saponin powder, the niobium-based solid acid catalyst and alcohol solvent II to obtain diosgenin. The application solves the problems that in the traditional process, the use of homogeneous catalysts such as sulfuric acid and hydrochloric acid can easily cause corrosion of equipment, and waste water is difficult to treat, and the recycling of the heterogeneous catalyst also makes the whole process have higher economic benefits.

Description

Technical Field

[0001] This application relates to a niobium-based solid acid catalyst and a method for preparing diosgenin, belonging to the field of biomedical technology. Background Technology

[0002] Diosgenin, also known as diosgenin, is a highly valuable pharmaceutical intermediate. It is an important raw material for the synthesis of various steroid hormones, such as adrenocorticotropic hormone, sex hormones, and anabolic steroids, including dexamethasone and cortisone. Dexamethasone has been proven effective in treating severely ill COVID-19 patients, significantly reducing mortality. It also possesses antibacterial, anti-inflammatory, and lipid-lowering properties.

[0003] Diosgenin is an isosspirane derivative, a steroidal saponin, and a product of the acid or enzymatic hydrolysis of diosgenin and other saponins. It is an important precursor in the synthesis of steroid drugs. Diosgenin itself also possesses certain pharmacological activities, showing efficacy in treating high cholesterol, stroke, diabetes, Alzheimer's disease, leukemia, menopausal syndrome, depression, and even cancer and various other metabolic diseases. In vitro studies have shown that diosgenin can minimize or reduce the growth rate of cancer cells, but research on its application in cancer treatment is still very limited. The global annual demand for diosgenin exceeds 4,000 tons, with the genera *Dioscorea*, *Smilax*, and *Fernonia* being the main sources for its extraction. In these plants, diosgenin mainly exists in the form of steroidal saponins, linked to glucose or rhamnose via CO glycosidic bonds to form different steroidal saponins.

[0004] Dioscorea shield-leaf, also known as yellow ginger, is a perennial twining vine. Its rhizomes contain 1%–15% steroidal saponins, making it the best plant source for extracting diosgenin. In China, Dioscorea shield-leaf is widely cultivated, primarily in Shiyan and Enshi in Hubei Province, Ankang in Shaanxi Province, and Luoyang in Henan Province.

[0005] In actual industrial production, glycosidic bonds are typically hydrolyzed first using strong inorganic acids such as hydrochloric acid or sulfuric acid to hydrolyze steroidal saponins into diosgenin, followed by extraction with petroleum ether. Acid hydrolysis is a simple, feasible, and economical method, but the use of large amounts of strong inorganic acids corrodes equipment, and the resulting large quantities of acidic wastewater and difficult-to-treat byproducts cause serious environmental pollution, limiting the development of the diosgenin industry. This major bottleneck has prompted attempts to develop environmentally friendly new methods for extracting diosgenin, leading to the development of many solutions with mild reaction conditions and clean production processes, such as microbial transformation and enzymatic hydrolysis. Although these methods are clean, their long cycles and high costs also limit their large-scale application. Summary of the Invention

[0006] The purpose of this invention is to provide a method for extracting diosgenin that produces no waste liquid, allows for the complete recycling of the alcohol solvent and solid acid catalyst used, achieves higher yield, is environmentally friendly, and has higher economic benefits.

[0007] According to one aspect of this application, a niobium-based solid acid catalyst is provided, said niobium-based solid acid catalyst being obtained by calcining a niobium-based solid acid catalyst precursor;

[0008] The niobium-based solid acid catalyst precursor includes a support and niobic acid supported on the support.

[0009] Optionally, the niobic acid is selected from Nb2O5·nH2O and / or NbOPO4.

[0010] Optionally, the carrier is selected from one of MCM-41, SBA-15, and ZSM-5.

[0011] According to another aspect of this application, a method for preparing diosgenin is provided, the method comprising the following steps:

[0012] (1) Extract the turmeric powder by reflux with alcohol solvent I, and dry it to obtain crude saponin powder;

[0013] (2) In a closed reactor, a mixture containing crude saponin powder, niobium-based solid acid catalyst and alcohol solvent II is reacted to obtain diosgenin.

[0014] The niobium-based solid acid catalyst is selected from the niobium-based solid acid catalysts described above.

[0015] Optionally, in step (2), the niobium-based solid acid catalyst is obtained by calcining a niobium-based solid acid catalyst precursor.

[0016] Optionally, the niobium-based solid acid catalyst precursor includes a support and niobic acid supported on the support.

[0017] Optionally, the niobic acid is selected from Nb2O5·nH2O and / or NbOPO4.

[0018] Optionally, the carrier is selected from one of MCM-41, SBA-15, and ZSM-5.

[0019] Optionally, in step (2), the mass ratio of the crude saponin powder to the niobium-based solid acid catalyst is 1:1.

[0020] Optionally, the mass-to-volume ratio of the crude saponin powder to alcohol solvent II is 0.1 g: 5-10 mL.

[0021] Optionally, the mass-volume ratio of the crude saponin powder to alcohol solvent II is selected from any value among 0.1g:5mL, 0.1g:6mL, 0.1g:7mL, 0.1g:8mL, 0.1g:9mL, 0.1g:10mL, or a range between any two of the above.

[0022] Optionally, in step (2), the niobium-based solid acid catalyst is recovered by filtration after the reaction.

[0023] Optionally, the calcination temperature is 100–500°C, and the calcination time is 5–8 hours.

[0024] Optionally, the roasting temperature is selected from any value of 100℃, 200℃, 300℃, 400℃, 500℃ or a range between any two of the above.

[0025] Optionally, the roasting time is selected from any value of 5h, 6h, 7h, 8h or a range between any two of the above.

[0026] Optionally, the alcohol solvent I and alcohol solvent II are independently selected from at least one of methanol, ethanol, isopropanol, n-propanol, n-butanol, isobutanol, and sec-butanol.

[0027] Optionally, in step (1), the solid-liquid ratio of the turmeric powder to the alcohol solvent I is 1:10-20 g / mL.

[0028] Optionally, the particle size of the turmeric powder is less than 0.075 mm.

[0029] Optionally, in step (1), the reflux extraction temperature is 80-120°C and the reflux extraction time is 6-10 hours.

[0030] Optionally, in step (1), the reflux extraction temperature is selected from any value of 80℃, 90℃, 100℃, 110℃, 120℃ or a range between any two of the above.

[0031] Optionally, the reflux extraction time is any value among 6h, 7h, 8h, 9h, and 10h, or a range between any two of the above.

[0032] Optionally, the drying temperature is 40–110°C, and the drying time is 12–24 hours.

[0033] Optionally, in step (2), the reaction temperature is 70–120°C and the reaction time is 3–8 hours.

[0034] Optionally, in step (2), the reaction temperature is selected from any value of 70℃, 80℃, 90℃, 100℃, 110℃, 120℃ or a range between any two of the above.

[0035] Optionally, in step (2), the reaction time is selected from any value of 3h, 4h, 5h, 6h, 7h, 8h or a range between any two of the above.

[0036] Optionally, in step (1), the ginger powder is obtained by physically crushing and sieving fresh ginger.

[0037] Optionally, in step (1), the alcohol solvent I is recovered after the reflux extraction is completed.

[0038] As a specific implementation method, this application is achieved through the following technical solution:

[0039] A method for extracting diosgenin from turmeric, the method comprising:

[0040] (1) Use physical methods to crush turmeric into particles, and after sieving, obtain turmeric powder.

[0041] (2) Add the turmeric powder obtained in step (1) to an alcohol solvent and heat under reflux to extract crude saponins. After the reflux is complete, filter to obtain the reaction solution. Then, recover the alcohol solvent by rotary evaporation and dry under vacuum to obtain crude saponin powder.

[0042] (3) The niobium-based solid acid catalyst is placed in a muffle furnace for calcination and then removed for later use.

[0043] (4) The crude saponin powder and niobium-based solid acid catalyst obtained in steps (2) and (3) are transferred to a reaction vessel, an alcohol solvent is added, and the reaction is carried out under heat and pressure. After the reaction is completed, the solid acid catalyst is recovered by filtration. After the reaction solution is brought to a certain volume, the yield of diosgenin is determined by high performance liquid chromatography.

[0044] Specifically, fresh turmeric is first pretreated by washing and drying the fresh turmeric tubers, then crushing them using a high-speed crusher and sieving to obtain refined turmeric powder. The turmeric powder and alcohol solvent are added to a round-bottom flask and heated under reflux in an oil bath. After reflux, the reaction solution is filtered. The alcohol solvent is recovered by rotary evaporation, and the resulting crude saponin powder is placed in a vacuum drying oven and dried overnight to obtain crude saponin powder. The niobium-based solid acid is calcined in a muffle furnace and then set aside. The crude saponin powder, alcohol solvent, and niobium-based solid acid catalyst are added to a high-pressure reactor, and the air is removed by purging with nitrogen five times. Then, the reaction is carried out under heat and pressure. After the reaction is completed, the solid acid catalyst is recovered by filtration, and the reaction solution is diluted to volume with methanol. The yield of diosgenin is then determined by high-performance liquid chromatography.

[0045] The beneficial effects that this application can produce include:

[0046] The present application provides a method for extracting crude saponin powder using alcohol solvents and preparing diosgenin by catalyzing the alcoholysis of crude saponin powder using solid acid catalysts. The entire process generates no waste liquid discharge, avoiding the environmental pollution and equipment corrosion problems caused by the use of inorganic strong acids such as sulfuric acid and hydrochloric acid in traditional industrial processes. At the same time, the reusability of solid acid catalysts greatly increases the economic benefits of the entire process.

[0047] This invention solves the problems of traditional processes where homogeneous catalysts such as sulfuric acid and hydrochloric acid can easily cause equipment corrosion and wastewater is difficult to treat. Furthermore, the recycling of heterogeneous catalysts makes the whole process more economical. Attached Figure Description

[0048] Figure 1 This is a liquid chromatogram of diosgenin in Example 1 of this application. Detailed Implementation

[0049] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0050] Unless otherwise specified, all raw materials used in the embodiments of this application were purchased through commercial channels.

[0051] Example 1

[0052] Fresh turmeric tubers were washed, crushed, dried, and sieved through a 200-mesh sieve. 5.0 g of the sieved turmeric powder (0.075 mm particle size) was transferred to a round-bottom flask and 75 mL of methanol was added. The oil bath temperature was set to 100°C, and the flask was placed in the oil bath and heated under reflux for 8 hours. After reflux, the flask was removed from the oil bath and cooled. The reaction solution was then obtained by filtration. The methanol was recovered from the reaction solution by rotary evaporation. The resulting solid was dried overnight in a vacuum drying oven at 45°C to obtain crude saponin powder.

[0053] Nb2O5·nH2O was placed in a muffle furnace and calcined at 300°C for 6 hours in air atmosphere. After cooling, it was taken out for use.

[0054] Accurately weigh 0.1 g of crude saponin powder and 0.1 g of Nb₂O₅·nH₂O into a reaction vessel, add 5 mL of methanol, tighten the lid, and purge the air with nitrogen five times. Using a programmed temperature riser, raise the temperature to 110 °C at a rate of 5 °C / min and react for 5 h. After the reaction, filter the solution through a 0.22 μm pore size filter to recover the niobium-based solid acid catalyst. Make up the volume with methanol, and then determine the yield using high-performance liquid chromatography (HPLC). The yield of diosgenin was 6.6%.

[0055] Example 2

[0056] Fresh turmeric tubers were washed, crushed, dried, and sieved through a 200-mesh sieve. 5.0 g of the sieved turmeric powder (0.045 mm particle size) was transferred to a round-bottom flask and 75 mL of ethanol was added. The oil bath temperature was set to 100°C, and the flask was placed in the oil bath and heated under reflux for 8 hours. After reflux, the flask was removed from the oil bath and cooled. The reaction solution was then obtained by filtration. Methanol was recovered from the reaction solution by rotary evaporation. The resulting solid was dried overnight in a vacuum drying oven at 45°C to obtain crude saponin powder.

[0057] NbOPO4 was placed in a muffle furnace and calcined at 200°C for 6 hours in air atmosphere. After cooling, it was taken out for use.

[0058] Accurately weigh 0.1 g of crude saponin powder and 0.1 g of NbOPO4 and transfer them to a reaction vessel. Add 5 mL of methanol, tighten the lid, and purge the air with nitrogen five times. Using a programmed temperature riser, raise the temperature to 110 °C at a rate of 5 °C / min and react for 5 h. After the reaction, filter the mixture through a 0.22 μm pore size filter to recover the niobium-based solid acid catalyst. Make up the volume with methanol, and then determine the yield using high performance liquid chromatography. The yield of diosgenin was 12.5%.

[0059] Example 3

[0060] Fresh turmeric tubers were washed, crushed, dried, and sieved through a 200-mesh sieve. 5.0 g of the sieved turmeric powder with a particle size of 0.035 mm was transferred to a round-bottom flask, and 75 mL of methanol was added. The oil bath temperature was set to 120 °C, and the flask was placed in the oil bath and heated under reflux for 10 hours. After reflux, the flask was removed from the oil bath and cooled. The reaction solution was then obtained by filtration. The methanol was recovered from the reaction solution by rotary evaporation, and the resulting solid was dried overnight in a vacuum drying oven at 45 °C to obtain crude saponin powder.

[0061] Nb₂O₅·nH₂O was loaded onto SBA-15 using a solution impregnation method. Simply put, 1 g of SBA-15 was dispersed in 20 mL of ethanol, and 0.395 g of NbCl₅ was accurately weighed and added to 5 mL of ethanol. The NbCl₅ solution was then added to the SBA-15 suspension while continuously stirring. Next, 1 mL of deionized water and 4 mL of ethanol were added, and the mixture was stirred for another 8 hours. The solvent was removed by rotary evaporation, and the resulting solid was dried at 100 °C for 6 hours and calcined at 550 °C for 6 hours. The resulting catalyst was designated Nb₂O₅·nH₂O / SBA-15. Nb₂O₅·nH₂O was loaded onto MCM-41 or ZSM-5 using the same method.

[0062] Accurately weigh 0.1 g of crude saponin powder and 0.1 g of Nb₂O₅·nH₂O into a reaction vessel, add 5 mL of methanol, tighten the lid, and purge the air with nitrogen five times. Using a programmed temperature riser, raise the temperature to 100 °C at a rate of 5 °C / min and react for 5 h. After the reaction, filter the solution through a 0.22 μm pore size filter to recover the niobium-based solid acid catalyst. Make up the volume with methanol, and then determine the yield using high-performance liquid chromatography (HPLC). The yield of diosgenin was 14.1%.

[0063] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A method for preparing diosgenin using a niobium-based solid acid catalyst, characterized in that, The method includes the following steps: (1) Extract the turmeric powder by reflux with alcohol solvent I, and dry it to obtain crude saponin powder; (2) In a closed reactor, a mixture containing crude saponin powder, niobium-based solid acid catalyst and alcohol solvent II is reacted to obtain diosgenin; The niobium-based solid acid catalyst is characterized in that it is obtained by calcining a niobium-based solid acid catalyst precursor; The niobium-based solid acid catalyst precursor includes a support and Nb2O5·nH2O and / or NbOPO4 supported on the support; The carrier is selected from one of MCM-41, SBA-15, and ZSM-5.

2. The method according to claim 1, characterized in that, In step (2), the mass ratio of the crude saponin powder to the niobium-based solid acid catalyst is 1:

1. The mass-to-volume ratio of the crude saponin powder to alcohol solvent II is 0.1 g: 5~10 mL.

3. The method according to claim 1, characterized in that, In step (2), the niobium-based solid acid catalyst is recovered by filtration after the reaction.

4. The method according to claim 1, characterized in that, The roasting temperature is 100~500℃, and the roasting time is 5~8h.

5. The method according to claim 1, characterized in that, The alcohol solvent I and alcohol solvent II are independently selected from at least one of methanol, ethanol, isopropanol, n-propanol, n-butanol, isobutanol, and sec-butanol.

6. The method according to claim 1, characterized in that, In step (1), the solid-liquid ratio of the turmeric powder to the alcohol solvent I is 1:10~20 g / mL; The particle size of the turmeric powder is less than 0.075 mm.

7. The method according to claim 1, characterized in that, In step (1), the temperature of the reflux extraction is 80~120℃, and the reflux extraction time is 6~10h; The drying temperature is 40~110℃, and the drying time is 12~24h.

8. The method according to claim 1, characterized in that, In step (2), the reaction temperature is 70~120℃ and the reaction time is 3~8h.

9. The method according to claim 1, characterized in that, In step (1), the ginger powder is obtained by physically crushing and sieving fresh ginger.

10. The method according to claim 1, characterized in that, In step (1), the alcohol solvent I is recovered after the reflux extraction is completed.

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