WO2021068991A1

WO2021068991A1 - Method for preparing diosgenin by ternary two-phase aluminum chloride hydrolysis

Info

Publication number: WO2021068991A1
Application number: PCT/CN2020/132078
Authority: WO
Inventors: 谢君; 张帅帅; 毕桂灿
Original assignee: 华南农业大学
Priority date: 2019-10-10
Filing date: 2020-11-27
Publication date: 2021-04-15
Also published as: CN110818770B; CN110818770A

Abstract

A method for preparing diosgenin by ternary two-phase AlCl₃ hydrolysis. Dried yam powder is placed into a reaction vessel, and then a ternary, two-phase solution consisting of an aqueous aluminum chloride solution, ethanol, and petroleum ether is added, the components are mixed even, and reacted at 130-180°C for 0.5-3.0 h, the reaction solution is filtered, residue is filtered out, and a petroleum ether layer is separated out for rotary evaporation, and after re-crystallization, diosgenin is obtained. In the present invention, the non-conventional acid and Lewis acid AlCl₃ is used for acidolysis in a ternary two-phase system to prepare diosgenin, thus improving diosgenin yield, shortening the extraction period, while also greatly reducing the amount of acid consumed, and more importantly, because concentrated sulfuric acid is not used, environmental pollution is also minimized. The invention therefore has great use potential.

Description

Method for preparing diosgenin by hydrolysis of ternary two-phase aluminum chloride

Technical field

The present invention relates to the technical field of plant extracts, particularly relates resource extraction diosgenin saponin, more particularly, it relates to a process for preparing Ternary AlCl ₃ biphasic hydrolysis diosgenin.

Background technique

Steroid hormone drugs are the world's second largest drug category after antibiotics. Diosgenin has a structure similar to steroid hormone drugs and is the most ideal precursor for the synthesis of steroid hormone drugs. There are as many as hundreds of three types of steroid hormone drugs synthesized from diosgenin as raw materials of adrenal cortex hormones, sex hormones and anabolic hormones. Therefore, the research and production preparation of saponins extracted from yam resources has a good market prospect and development value.

Diosgenin and different types and numbers of sugars are combined by glycosidic bonds to form different diosgenin. Therefore, the hydrolysis of diosgenin is the key to the extraction and preparation of diosgenin. The current preparation technology of diosgenin is mainly based on two methods, chemical hydrolysis and biological hydrolysis, and some auxiliary extraction preparation techniques or techniques combining multiple methods have been derived from this.

The chemical hydrolysis method mainly refers to the extraction and preparation method of using traditional strong inorganic acids such as sulfuric acid and hydrochloric acid to hydrolyze glycosidic bonds to release diosgenin. The traditional process of extracting diosgenin by acid hydrolysis was proposed by Rothrock et al., that is, hydrolyzing the rhizome of dioscorea directly with inorganic acid, washing it with water to neutrality, drying and using petroleum ether and other organic solvents for water bath circulation extraction, and finally crystallizing to obtain the finished saponin product . Zhang Yuqing et al. investigated the effect of extracting diosgenin by hydrolysis with sulfuric acid, and the results showed that the yield of saponin was 1.28% after hydrolysis at a concentration of 2mol/L for 4h, 8h after Soxhlet extraction. The direct acid hydrolysis method has simple process and simple operation, and is suitable for large-scale industrial production. However, the yield of saponin in the inorganic acid hydrolysis process is generally low, about 1.6%. When using a strong inorganic acid to hydrolyze, it will not only cause equipment corrosion and large water consumption during washing, the discharged acidic wastewater is difficult to recycle, and there is a part of the waste residue. The saponins could not be separated from the starch and cellulosic substances present in a large amount after acid hydrolysis. This directly causes environmental pollution and waste of resources, and also affects the yield of diosgenin. The biohydrolysis method for extracting saponin is the use of biological enzymes produced by some mold microorganisms to directly convert saponin to produce saponin, which has the advantage of being environmentally friendly and pollution-free. Some researchers used Aspergillus oryzae, Trichoderma harzianum, and Aspergillus awamori to inoculate Dioscorea zingiberensis to ferment and directly use saponin conversion to extract saponin. The research results confirmed that the yield of diosgenin varies from 17.06mg/g to 74.26mg/g. The difference is significant, the process and mechanism of biotransformation using saponin hydrolysis are complicated, the yield of saponin is low, and more by-products are generated. Although the combination of biological methods and enzymatic hydrolysis to convert saponins into diosgenin has no pollution to the environment, it has attracted the attention of many researchers. However, compared with the traditional direct acid hydrolysis method, the cost of enzyme preparations is uneconomical and biological. The inefficiency of transformation leads to its limited application in the diosgenin industry. As the traditional preparation technology of saponin is faced with the problems of low yield, high acid consumption, large sewage discharge, starch waste and acid waste liquid cannot be recycled, or high recycling cost, and other problems such as excessive resource consumption, it is urgent to find a saponin yield The preparation method of diosgenin is high, low in acid consumption and small in sewage discharge.

Summary of the invention

Object of the present invention to overcome the prior art drawbacks and deficiencies exist, there is provided a process for preparing Ternary AlCl ₃ biphasic hydrolysis diosgenin.

The above objectives of the present invention are achieved through the following technical solutions:

A method for preparing diosgenin by hydrolysis of ternary biphasic AlCl ₃ , put the dried dioscorea powder into a reaction kettle, and then add a ternary biphasic solution composed of aluminum trichloride aqueous solution, ethanol and petroleum ether, and mix After homogenization, react at 130-180°C for 0.5-3.0h, filter the reaction solution, filter off the residue, separate the petroleum ether layer, perform rotary evaporation, and obtain diosgenin after recrystallization.

The method of the present invention adopts non-traditional acid aluminum trichloride easy acid hydrolysis in a ternary biphasic system of ethanol/water/petroleum ether to prepare diosgenin. Lewis acid aluminum trichloride is a water-soluble inorganic salt Class, the aqueous solution is acidic, safe, non-toxic and easy to operate, and can be used to replace the strong inorganic acid and sulfuric acid hydrolysis to prepare saponin. Since the polarity of diosgenin is very different from the polarity of steroidal saponins, compared with steroidal saponins, diosgenin has weaker polarity due to the absence of sugar chains, which makes it difficult to extract both saponin and various saponins at the same time. Diosgenin, by adding petroleum ether to the reaction system, the difference in solubility of saponins and saponin is used to simultaneously extract saponin into the petroleum ether organic phase while saponin is hydrolyzed, so that the acid hydrolysis of saponin and the extraction of saponin are performed simultaneously; at the same time, The weak acidity of aluminum chloride and part of the saponins are encapsulated by starch or attached to the cell wall and are difficult to be released. The steroidal saponins in dioscorea chrysanthemum have not been fully utilized to convert saponin. The present invention selects a mixed solvent of ethanol and water. Conducive to the extraction of total saponin, so that saponin can be prepared by acid hydrolysis to a greater extent to obtain saponin. _{The method for preparing saponin by the ternary two-phase AlCl 3} hydrolysis assisted by the ethanol extractant of the present invention significantly improves the yield of saponin, shortens the extraction period, and at the same time greatly reduces the consumption of acid, and does not use concentrated H ₂ SO ₄ In this case, the pollution to the environment will also be minimized.

Preferably, the reaction temperature is 140-170°C. Appropriate and favorable temperature can accelerate the reaction process, while at the same time it can also reduce the extraction time and improve the extraction efficiency. However, the extremely high temperature may promote the partial gelatinization of the high content of starch in Dioscorea zingiberensis, causing some starch-coated saponin not to be hydrolyzed and converted into saponin, causing the loss of saponin yield. More importantly, an appropriate temperature will reduce the viscosity of the ternary two-phase solvent and increase the diffusion coefficient of the ternary two-phase solvent, thereby accelerating the hydrolysis of saponin in the water layer and improving the extraction of diosgenin transferred to petroleum ether. effectiveness.

More preferably, the reaction temperature is 140-160°C (preferably 150°C).

Preferably, the reaction time is 1 to 2.5 hours (preferably 2.0 hours).

Preferably, the concentration of the aluminum trichloride aqueous solution is 1.25 g/L to 15 g/L.

Preferably, the concentration of the aluminum trichloride aqueous solution is 2.5 g/L to 15 g/L.

When the AlCl ₃ concentration is too low, the low-concentration AlCl ₃ solution is obviously not enough to completely hydrolyze the steroidal saponins, and can only break the steroidal saponins part of the glycosidic bond, so that the saponins are hydrolyzed into some intermediate products, such as diosgenin-triglycoside, Diosgenin-diglycoside and trillium glucoside, etc.; while too high concentration of AlCl ₃ solution may cause side reactions, which will cause the dehydration and cyclization of saponin and affect the yield of saponin. Therefore, the concentration of the aluminum trichloride aqueous solution is preferably 3.75 to 6.25 g/L (more preferably 5.0 g/L).

Preferably, the volume ratio of the ethanol/water/petroleum ether solution is 6-15:16:8-32; for example, 6:16:32, 10:16:25, 15:16:20.

More preferably, the volume ratio of ethanol/water/petroleum ether solution is 15:16:20.

Preferably, the addition amount of the yam powder in the reaction system is 18-20 g/L. (Preferably 19.6g)

Preferably, the dioscorea dinosaur is dioscorea dinosaur; due to its high saponin content, dioscorea dinosaur is a more ideal raw material for saponin production.

As a preferred embodiment, the _{method for preparing diosgenin by hydrolysis of ternary two-phase AlCl 3} is to add 5.0 g of dioscorea powder after drying into a closed reactor, and then add 80 mL of 5.0 g/L aluminum trichloride. Aqueous solution, 75mL ethanol, 100mL petroleum ether, mix well, react at 160℃ for 2.0h, filter the reaction solution, filter off the residue, separate the petroleum ether layer for rotary evaporation, recrystallize to obtain diosgenin, the saponin yield can be Reached 3.21%.

Compared with the prior art, the present invention has the following beneficial effects:

The method of the present invention adopts the non-traditional acidic acid aluminum trichloride in the ternary biphasic system of ethanol/water/petroleum ether to prepare diosgenin, and uses _{the new ternary biphasic AlCl 3} hydrolysis of the present invention. The highest yield of saponin obtained by the method reached 3.21%, and the increase rate of saponin was 22.05% higher than that of the traditional sulfuric acid method, _{67.19% higher than that of the two-phase AlCl 3} hydrolysis method without ethanol, and even 2.7 of the two-phase sulfuric acid hydrolysis method. Times more. _{The method for preparing saponin by ternary two-phase AlCl 3} hydrolysis assisted by the ethanol extractant of the present invention significantly improves the saponin yield, shortens the extraction period, and greatly reduces the consumption of acid. More importantly, without the use of concentrated H ₂ SO ₄ , the pollution to the environment will also become minimal, which has a larger application prospect.

Detailed ways

The present invention will be further described below in conjunction with specific embodiments, but the embodiments do not limit the present invention in any form. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the technical field.

Unless otherwise specified, the reagents and materials used in the following examples are all commercially available.

Experimental material: Three-year-old chrysanthemum leaf dioscorea tuber, taken from the chrysanthemum leaf dioscore plant base in Wengyuan County, Guangdong Province. Then cut the three-year-old chrysanthemum leaf yam rhizome into thin slices, freeze-dried for 24 hours with a freeze dryer to remove excess water, then grind it into powder with a grinder, put it into a sealed bag, and store it in a thermostatic dewatering sealer for later use.

Diosgenin standards (≥99.9%, HPLC grade), purchased from Fluka, USA; methanol, chromatographically pure, purchased from Sigma-Aldrich, USA; petroleum ether (60-90℃), analytically pure, purchased from Tianjin Fuyu Fine Chemical Co., Ltd.; absolute ethanol, glucose, aluminum trichloride, analytically pure, purchased from Shanghai Sinopharm Chemical Reagent Co., Ltd.; sodium hydroxide, analytically pure, purchased from Guangzhou Chemical Reagent Factory; potassium sodium tartrate, sodium sulfite, heavy Distilled phenol and 3,5-dinitrosalicylic acid, analytically pure, were purchased from Aladdin Reagent (Shanghai) Co., Ltd.

Example 1

Accurately weigh 5.0g of Dioscorea chrysanthemum powder into a 300mL Parr reactor, then add _{a ternary two-phase solution consisting of 80mL of 4.0g/L AlCl 3} aqueous solution, 75mL of ethanol and 100mL of petroleum ether. After stirring, set the reactor The rotation speed is 150 rpm, and the reaction is carried out for 2.0 h at an extraction temperature of 150°C. After the end, the diosgenin extract in the petroleum ether organic phase was rotary evaporated, concentrated, crystallized, and dissolved in chromatographic grade methanol to prepare a sample for later use. Then quantify the diosgenin analysis. Collect the waste water solution at the bottom for subsequent COD analysis.

The analysis method of diosgenin is: dilute the diosgenin extract dissolved in methanol at a constant volume, dilute it by a certain multiple, filter it with a 0.22μm filter membrane, and collect it into a 1mL sample bottle for sample preparation. With Fluka's saponin standard product (purity ≥99.9%) as a control, high performance liquid chromatography was performed. The specific process is as follows: After the standard substance of diosgenin is dissolved in methanol, the concentrations of 4.0×10 ^-3 mg/mL, 2.0×10 ^-2 mg/mL, 1.0×10 ^-1 mg/mL and 0.5 are determined by high performance liquid chromatography. The mg/mL diosgenin standard was determined. Based on the chromatographic peak area of the saponin standard, a standard curve was drawn, and the peak area was used as the quantitative basis for the sample. The saponin yield was calculated by the following formula:

Where W: Dioscorea daisy raw material weight, g; C: Saponin concentration, mg/mL; N: Dilution multiple. HPLC measurement parameters: UV detector; C18 chromatographic column (4.6mm×250mm, 5μm); column oven temperature: 40℃; mobile phase: methanol/water; flow rate: 1.0mL/min; sample volume: 10μL. Each measurement was repeated three times.

The results show that the yield of saponin prepared by the method described in Example 1 can reach 3.08%.

Example 2

This example examines the influence of temperature on the yield of saponin in the ternary two-phase system. Accurately weigh out 5.0g of Dioscorea chrysanthemum powder into a 300mL Parr reactor, then add _{a ternary biphasic solution consisting of 80mL of 5.0g/L AlCl 3} aqueous solution, 75mL of ethanol and 100mL of petroleum ether. After stirring, set the reactor. The rotation speed is 150 rpm. After the temperature of the reactor rises to a predetermined series of temperatures (130°C, 140°C, 150°C, 160°C, 170°C, 180°C), the timing starts, and the reaction time is 2.0h. After the end, the diosgenin extract in the petroleum ether organic phase was rotary evaporated, concentrated, crystallized, and dissolved in chromatographic grade methanol to prepare a sample for later use. According to the analysis method in Example 1, the yield of diosgenin of chrysanthemum leaf was calculated, and the influence of temperature on the yield of saponin extracted _{by AlCl 3 in the ternary two-phase system was investigated.} The results are shown in Table 1:

Table 1

It can be seen from Table 1 that in the temperature range of 130～150℃, the yield of diosgenin increases significantly with increasing temperature, the maximum yield of saponin is 3.21%, and when the temperature exceeds 160℃, the yield of saponin is Slowly lowered again. This is because a suitable and favorable temperature can accelerate the reaction process, while at the same time it can also reduce the extraction time and improve the extraction efficiency. However, the extremely high temperature may promote the partial gelatinization of the high content of starch in the dioscorea chrysanthemum, causing some starch-coated saponins not to be hydrolyzed and converted into saponin, causing the loss of saponin yield. More importantly, an appropriate temperature will reduce the viscosity of the ternary two-phase solvent and increase the diffusion coefficient of the ternary two-phase solvent, thereby accelerating the hydrolysis of saponin in the water layer and improving the extraction of diosgenin transferred to petroleum ether. effectiveness. Therefore, a temperature of 150°C is the optimal extraction temperature and the maximum yield of diosgenin is 3.21%.

Example 3

This example examines the effect of extraction time on the yield of saponin in the ternary two-phase system. Accurately weigh 5.0g Dioscorea chrysanthemum powder into a 300mL Parr reactor, then add _{a ternary biphasic solution consisting of 80mL 5.0g/L AlCl 3} aqueous solution, 75mL ethanol and 100mL petroleum ether. After stirring evenly, set the reactor The rotation speed is 150 rpm, and the reaction is performed at an extraction temperature of 150° C. (0.5h, 1.0h, 1.5h, 2.0h, 2.5h, 3.0h). After the end, the diosgenin extract in the petroleum ether organic phase was rotary evaporated, concentrated, crystallized, and dissolved in chromatographic grade methanol to prepare a sample for later use. According to the analysis method in Example 1, the yield of diosgenin from chrysanthemum leaf was calculated, and the effect of reaction time on the yield of saponin extracted _{by AlCl 3 in the ternary two-phase system was investigated.} The results are shown in Table 2:

Table 2

It can be seen from Table 2 that when the extraction time is 0.5 h, a saponin yield of 2.69% can be obtained. When the extraction time is prolonged, the yield of diosgenin slowly increases. When the extraction time is 2.0h, the saponin content reaches the maximum value of 3.21%, and the yield of saponin in the rest of the time period is not much different. With the further extension of the extraction time, the content of diosgenin decreased slightly, indicating that the steroidal carbon skeleton of saponin was likely to be gradually destroyed in a high-temperature solution for a long time, but the loss was not very large. Therefore, the best reaction time is 2.0h.

Example 4

In this example _{, the influence of the concentration of the AlCl 3} solution on the yield of saponin in the ternary two-phase system was investigated. Accurately weigh out 5.0g dioscorea chrysanthemum powder into a 300mL Parr reactor, and then add 80mL AlCl ₃ aqueous solutions of different concentrations (1.25g/L, 2.5g/L, 3.75g/L, 5.0g/L, 6.25g/ L, 10g/L, 15g/L), 75mL ethanol and 100mL petroleum ether ternary biphasic solution, after stirring evenly, set the reactor speed to 150rpm, and react at the extraction temperature of 150°C for 2.0h respectively. After the end, the diosgenin extract in the petroleum ether organic phase was rotary evaporated, concentrated, crystallized, and dissolved in chromatographic grade methanol to prepare a sample for later use. Calculates Dioscorea saponin yield analysis method according to Example 1 embodiment, the effects of different concentrations of a solution of AlCl ₃ AlCl ₃ in saponin extraction yield in the ternary phase system. The results are shown in Figure 3:

table 3

It can be seen from Table 3 that as the _{concentration of the AlCl 3} solution increases from 1.25 g/L to 3.75 g/L, the saponin yield increases significantly, indicating that the _{concentration of the AlCl 3} solution plays an important role in the hydrolysis of saponin and directly affects the saponin The output. When the _{concentration of AlCl 3} solution reaches 5.0 g/L, the yield of saponin is the highest. However, when more aluminum trichloride is added as an acid hydrolysis catalyst, the yield of saponin decreases significantly, indicating that high-concentration AlCl ₃ solution may destroy the saponin produced by excessive hydrolysis and ionization of hydrogen ions, leading to side reactions. That is, saponin can be easily dehydrated to form △3,5-deoxysapogenin and modified into furan derivatives after opening the F-spiroacetal ring. _{Therefore, an AlCl 3} solution with a concentration of 5.0 g/L is sufficient for extraction to obtain the highest yield of saponin.

Example 5

This example investigates the influence of the ethanol/water ratio on the yield of saponin in the ternary two-phase system. Accurately weigh 5.0g Dioscorea chrysanthemum powder into a 300mL Parr reactor, then add _{a ternary biphasic solution consisting of 80mL 5.0g/L AlCl 3} aqueous solution, different volumes of ethanol and 100mL petroleum ether. After stirring evenly, set the reaction The speed of the kettle was 150 rpm, and the reaction was carried out at an extraction temperature of 150° C. for 2.0 hours. After the end, the diosgenin extract in the petroleum ether organic phase was rotary evaporated, concentrated, crystallized, and dissolved in chromatographic grade methanol to prepare a sample for later use. According to the method in Example 1, the yield of diosgenin of chrysanthemum leaf was calculated, and the influence of water/petroleum ether solution of different volume ratios on the yield of saponin extracted _{by AlCl 3 in the ternary two-phase system was investigated.} The results are shown in Table 4:

Table 4

To a large extent, more steroidal saponins are extracted from the dioscorea raw materials by the extraction solvent ethanol and dissolved in the acidic aqueous phase, which means that the content of saponin produced by hydrolysis of saponins is higher. It can be seen from Table 4 that as the volume ratio of ethanol increases, the yield of saponin is gradually increasing. When the maximum yield of saponin is 3.21%, the ratio of ethanol/water is 15/16 (v/v); When the amount of ethanol continued to increase, the yield of diosgenin decreased slightly, indicating that the dissolution of steroidal saponins reached saturation at this time. Therefore, the ethanol water solvent with a ratio of 15/16 (v/v) was selected as the best condition for extracting saponin from Dioscorea chrysanthemum.

Example 6

This example examines the influence of the volume ratio of water/petroleum ether on the yield of saponin in the ternary two-phase system. Accurately weigh 5.0g of Dioscorea chrysanthemum powder into a 300mL Parr reactor, and then add _{a ternary biphasic solution consisting of 80mL of 5.0g/L AlCl 3} aqueous solution, 75mL of ethanol and different proportions of petroleum ether. After stirring, set the reaction. The speed of the kettle was 150 rpm, and the reaction was carried out at an extraction temperature of 150° C. for 2.0 hours. After the end, the diosgenin extract in the petroleum ether organic phase was rotary evaporated, concentrated, crystallized, and dissolved in chromatographic grade methanol to prepare a sample for later use. According to the method in Example 1, the yield of diosgenin of chrysanthemum leaf was calculated, and the influence of water/petroleum ether solution of different volume ratios on the yield of saponin extracted _{by AlCl 3 in the ternary two-phase system was investigated.} The results are shown in Table 5:

table 5

It can be seen from Table 5 that when the volume ratio of water/petroleum ether is 80mL/100mL, the highest saponin yield is obtained, and as more petroleum ether is consumed, the saponin yield decreases; in addition; If the amount of petroleum ether is less than 60 mL, the saponin yield has just reached about 2.69%. This indicates that less petroleum ether solvent is not enough to extract and completely dissolve the saponin produced by hydrolysis, and it is impractical and uneconomical to consume more petroleum ether solvent. Therefore, considering the influence of petroleum ether in various aspects, the optimal volume ratio of water/petroleum ether is determined to be 80mL/100mL.

Example 7

In this example, the effect of the stirring rate (rotation speed) on the yield of saponin in the ternary two-phase system was investigated. Accurately weigh 5.0g Dioscorea chrysanthemum powder into a 300mL Parr reactor, and then add _{a ternary biphasic solution consisting of 80mL 5.0g/L AlCl 3} aqueous solution, 75mL ethanol and 100mL petroleum ether. After stirring evenly, set the reaction separately The speed of the kettle is (50 rpm, 100 rpm, 150 rpm, 200 rpm, 250 rpm), and the reaction is carried out at an extraction temperature of 150° C. for 2.0 h. After the end, the diosgenin extract in the petroleum ether organic phase was rotary evaporated, concentrated, crystallized, and dissolved in chromatographic grade methanol to prepare a sample for later use. According to the method in Example 1, the yield of diosgenin of chrysanthemum leaf was calculated, and the influence of water/petroleum ether solution of different volume ratios on the yield of saponin extracted _{by AlCl 3 in the ternary two-phase system was investigated.} The results are shown in Table 6:

Table 6

It can be seen from Table 6 that compared with other influencing factors, the stirring rate has only a small effect on the saponin yield. Among these stirring speeds of 50 to 250 rpm, the saponin yield reaches the highest at 100 rpm, which is only slightly higher than other higher stirring speeds. The reason why the higher agitation rate results in less saponin production can be attributed to the insufficient contact time between the acidolysis substrate and the acid catalyst and the insufficient reaction time. It can be seen that the stirring rate, which is an influencing parameter, has a gentle and mild influence on the extraction of diosgenin from Chrysanthemum leaves, with the lowest saponin yield being 3.01% and the highest being 3.21%.

The optimal extraction technical parameters optimized through the above-mentioned examples are that the dried Dioscorea zingiberensis powder uses 80 mL of an AlCl ₃ solution with a concentration of 5.0 g/L and a volume ratio of 15/16/20 (v/v) at a temperature of 150°C. /v) Under the treatment of ethanol/water/petroleum ether (ie, 80 mL of AlCl ₃ aqueous solution, 75 mL of ethanol and 100 mL of petroleum ether), the yield of diosgenin extracted by this method reached 3.21%.

Comparative example 1

Method 1: Biphasic acid hydrolysis: replace aluminum trichloride with 0.5mol/L concentrated sulfuric acid, hydrolyze for 1.5h at 140℃ under the optimal reaction conditions, and repeat the extraction of diosgenin from diosgenin with aluminum trichloride step.

Method 2: Traditional direct acid hydrolysis: 20.0g Dioscorea chrysanthemum powder was hydrolyzed in 200mL 2mol/L concentrated sulfuric acid aqueous solution for 2.0h. After filtering the mixture, the solid residue was washed with 200 mL of hot water and dried at 80°C. Then, the solid residue was used to extract diosgenin through a Soxhlet extractor with petroleum ether repeatedly at reflux for 4 hours.

Method 3: Biphasic AlCl ₃ : Add 5.0g of dried chrysanthemum dioscorea powder into a closed reactor, add 80mL of 4.0g/L aluminum trichloride solution in sequence, mix well, then add 100mL petroleum ether, and react at 160℃ After 2h, the reaction solution was filtered, the residue was filtered off, the petroleum ether layer was separated, and rotary evaporated, and diosgenin was obtained after recrystallization.

1. Extract diosgenin according to the optimal extraction technical parameters optimized in the present invention, and compare the yield of diosgenin prepared by the above-mentioned methods 1 to 3, and investigate the yield increase and solid residues. Acid consumption and other related variables, the results are shown in Table 7:

Table 7

The results in Table 7 show that the method of using the ternary two-phase AlCl ₃ solution of the present invention has a 22.05% increase in the yield of saponin obtained from the traditional sulfuric acid method, and even more than 2.7 times that of the two-phase sulfuric acid hydrolysis method. Compared with the extraction time consumption of 6 hours in the traditional sulfuric acid method, the _{extraction process of diosgenin using ternary two-phase AlCl 3} solution hydrolysis only takes 2 hours, which is only 0.5h longer than the two-phase sulfuric acid hydrolysis method. Similarly, without the use of sulfuric acid for saponin extraction, the _{hydrolysis yield of saponin in the ternary two-phase AlCl 3} solution was 67.19% higher than that of the two-phase AlCl _{3 hydrolysis method without ethanol.}

Compared with the extraction time consumption of 6 hours in the traditional sulfuric acid method, _{the process of preparing diosgenin using ternary two-phase AlCl 3} hydrolysis only takes 2 hours. The ternary two-phase AlCl ₃ hydrolysis method of the present invention uses an acid dosage of 0.5 g of AlCl ₃ , which is significantly lower than the traditional sulfuric acid method of 39.21 g of concentrated H ₂ SO ₄ , which also makes the pH value of the waste liquid higher than The traditional sulfuric acid method makes it easier to handle for subsequent fermentation experiments. The method of preparing saponin by using ethanol extractant-assisted ternary two-phase AlCl ₃ hydrolysis significantly improves the yield of saponin, shortens the extraction period, and at the same time greatly reduces the amount of acid consumed. More importantly, it does not use concentrated H ₂ In _{the case of SO 4} , the pollution to the environment will also be greatly reduced. It also shows that the method of ternary two-phase AlCl ₃ hydrolysis to extract saponin assisted by ethanol extractant significantly improves the yield of saponin and shortens the acid hydrolysis time. At the same time, no use and consumption of _{concentrated H 2} SO _{4 means environmental pollution.} It will also become the smallest.

_{Therefore, the ternary two-phase AlCl 3} hydrolysis method for preparing saponin assisted by the ethanol extractant of the present invention significantly improves the saponin yield, shortens the extraction period, and greatly reduces the consumption of acid. More importantly, without the use of concentrated H ₂ SO ₄ , the pollution to the environment will also become minimal, which has a larger application prospect.

Claims

A method for preparing diosgenin by hydrolysis of ternary biphasic AlCl 3 is characterized in that the dried dioscorea powder is put into a reactor, and then a ternary diosgenin composed of aluminum trichloride aqueous solution, ethanol and petroleum ether is added. The phase solution is mixed and reacted at 130-180°C for 0.5-3.0h, the reaction solution is filtered, the residue is filtered off, the petroleum ether layer is separated, and the petroleum ether layer is rotary evaporated, and diosgenin is obtained after recrystallization.
The method according to claim 1, wherein the reaction temperature is 140-170°C.
The method of claim 1, wherein the reaction time is 1 to 2.5 hours.
The method according to claim 1, wherein the concentration of the aluminum trichloride aqueous solution is 1.25 g/L to 15 g/L.
The method according to claim 1, wherein the volume ratio of the ethanol/water/petroleum ether solution is 6-15:16:8-32.
The method according to claim 1, wherein the addition amount of the yam powder in the reaction system is 18-20 g/L.
The method according to claim 1, characterized in that the dried 5.0g yam powder is added to a closed reactor, and then 80mL 5.0g/L aluminum trichloride aqueous solution, 75mL ethanol, 100mL petroleum ether are added, and the mixture is mixed evenly. After reacting at 160°C for 2 hours, the reaction solution was filtered, the residue was filtered off, and the petroleum ether layer was separated for rotary evaporation, and diosgenin was obtained after recrystallization.
The method according to any one of claims 1-7, wherein the yam is Dioscorea chrysanthemum.