Preparation method of high-purity 24-dehydrocholesterol

Abstract

The invention discloses a preparation method of high-purity 24-dehydrocholesterol. The invention provides a preparation method of high-purity 24-dehydrocholesterol, which comprises the following steps: S1, in an organic solvent, reacting a compound as shown in a formula I in the presence of a catalyst and a compound as shown in a formula II; s2, carrying out saponification reaction on the product in the step S1; s3, dissolving the saponified product by using an organic solvent, and washing with water at 40-80 DEG C; s4, mixing the crude product 1 with an organic solvent at 40-90 DEG C, and dissolving; crystallizing under the condition of 10 to 30 DEG C; s5, mixing and dissolving the crude product 2 and an organic solvent at 40-90 DEG C; and recrystallizing under the condition of 10 to 30 DEG C to obtain the 24-dehydrocholesterol. The preparation method provided by the invention has the advantages that the process steps are simple, the product purity is high, and large-scale preparation is facilitated. # imgabs0 # imgabs1 #

Description

Technical Field

[0001] The invention relates to the technical field of organic chemical synthesis, and in particular to a method for preparing high-purity 24-dehydrocholesterol. Background Art

[0002] 24-Dehydrocholesterol, also known as sterol and 3β-hydroxy-5,24-cholestadiene, is a white powder or crystal, and is a molecule similar to cholesterol. 24-Dehydrocholesterol is of great significance in biological and medical research. It is an important pharmaceutical intermediate and can be used as an important product in the study of cholesterol metabolism. It is also widely used in scientific research experiments as a chemical reagent or reference substance.

[0003]

[0004] 24-Dehydrocholesterol

[0005] Existing methods for preparing 24-dehydrocholesterol generally include the following methods, for example:

[0006] (a) Fractional extraction method

[0007] This method (CN101270141A) uses a mixture of 24-dehydrocholesterol and cholesterol as raw materials, dissolves them in a solvent to prepare a raw material liquid, fractionates and extracts the raw material liquid, collects and concentrates the extract to obtain 24-dehydrocholesterol. The amount of fractionation extraction solvent used is large, and the 24-dehydrocholesterol obtained after the extract is concentrated has low purity, and further purification cannot obtain 24-dehydrocholesterol with higher purity.

[0008] (b) Solvent crystallization method

[0009] This method (CN101307086A) uses crude 24-dehydrocholesterol extracted from lanolin as raw material, and obtains 24-dehydrocholesterol with a purity greater than 90% through multiple crystallizations using different solvents. Multiple crystallizations using different solvents are cumbersome, and the obtained 24-dehydrocholesterol still contains a large amount of impurities with similar structures.

[0010] (c) Fixed bed adsorption purification method

[0011] This method (CN101307087A) uses crude 24-dehydrocholesterol extracted from lanolin as raw material, and separates it by adsorption on an activated carbon fixed bed to obtain a 24-dehydrocholesterol product with a purity greater than 60%. The fixed bed adsorption purification method also uses a large amount of solvent and the purity of the obtained 24-dehydrocholesterol is low.

[0012] (d) Simulated moving bed chromatography

[0013] This method (Xu Qingqing. Separation and purification of chain sterols by simulated moving bed chromatography [J]. Analytical Chemistry, 2013, (6): 851-855., CN117886876A, CN102924555A) uses the crude 24-dehydrocholesterol extracted from lanolin as raw material, and uses reverse phase high performance liquid chromatography (RP-HPLC) combined with simulated moving bed chromatography (SMBC) capable of continuous operation to separate and purify 24-dehydrocholesterol. This method can obtain 24-dehydrocholesterol with high purity, but the amount of solvent used is large, the separation equipment is expensive, and it is not suitable for large-scale preparation.

[0014] In addition, there are ionic liquid extraction separation method (CN102718826A) which is similar to fractionation extraction method; complexation / chromatographic column crystallization separation method (CN113135972A, CN113735931A) which is similar to different solvent crystallization methods. None of them can obtain high-purity 24-dehydrocholesterol.

[0015] In summary, in the prior art, when preparing 24-dehydrocholesterol, the crude 24-dehydrocholesterol obtained by lanolin extraction is used as the raw material, and the amount of solvent used for separation and purification is large, the cost is high, and the operation is complicated. In addition, the 24-dehydrocholesterol obtained by separation and purification by fractionation extraction, solvent crystallization, and fixed bed adsorption has low purity and cannot be used as a reagent or reference substance. Summary of the invention

[0016] The technical problem to be solved by the present invention is that the preparation of high-purity 24-dehydrocholesterol in the prior art requires the use of expensive separation instruments, has high costs, and is not suitable for mass production. To this end, the present invention provides a method for preparing high-purity 24-dehydrocholesterol. The preparation method provided by the present invention has the advantages of simple process steps, high product purity, and is conducive to large-scale preparation.

[0017] The present invention adopts the following technical solutions to solve the above technical problems.

[0018] The present invention provides a method for preparing high-purity 24-dehydrocholesterol, which comprises the following steps:

[0019] S1: reacting the compound represented by formula I in the presence of a catalyst and a compound represented by formula II in an organic solvent to obtain a product;

[0020]

[0021] in,

[0022] R 1 and R 2 are independently H or -C(O)-R a , R aH, C 1-4 Alkyl, -C(O)-OH or one or more R a1 Substituted C 1-4 alkyl;

[0023] R 3 -C(O)-R a , R a H, C 1-4 Alkyl, -C(O)-OH or one or more R a1 Substituted C 1-4 alkyl;

[0024] R a1 are independently halogen or hydroxy;

[0025] In step S1, the organic solvent is composed of an organic solvent A1 and an organic solvent A2, the organic solvent A1 is selected from one or more of an aromatic hydrocarbon solvent, a halogenated alkane solvent and a halogenated aromatic hydrocarbon solvent, and the organic solvent A2 is an alkane solvent;

[0026] In step S1, the catalyst is selected from one or more of sulfuric acid, phosphoric acid, p-toluenesulfonic acid, trifluoromethanesulfonic acid, sodium bisulfate, potassium bisulfate, zinc chloride, ferric chloride, titanium tetrachloride, aluminum chloride and calcium chloride;

[0027] S2: Under the action of a base, the product in step S1 is subjected to a saponification reaction in an organic solvent; and then subjected to a neutralization reaction with an acid to obtain a saponification product;

[0028] In step S2, the organic solvent consists of an organic solvent B1 and an organic solvent B2, the organic solvent B1 is selected from one or both of an alcohol solvent and a ketone solvent, and the organic solvent B2 is selected from one or both of an alkane solvent and an aromatic solvent;

[0029] S3: using an organic solvent to dissolve the saponification product, and then washing the saponification product solution with water at 40° C.-80° C. to obtain a crude product 1 of 24-dehydrocholesterol;

[0030] S4: mixing the crude product 1 with an organic solvent to dissolve at 40-90° C.; then cooling to 10-30° C. to crystallize, to obtain a crude product 2 of 24-dehydrocholesterol;

[0031] S5: Mix the crude product 2 with an organic solvent to dissolve it at 40-90° C.; then cool it to 10-30° C. to recrystallize it to obtain 24-dehydrocholesterol.

[0032] In one embodiment, the C 1-4 Alkyl and one or more R a1 Substituted C1-4 C in the alkyl group 1-4 Alkyl is independently methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl or tert-butyl, for example methyl or ethyl.

[0033] In a certain embodiment, the halogen is fluorine, chlorine, bromine or iodine, such as fluorine or chlorine.

[0034] In one embodiment, the one or more R a1 Substituted C 1-4 The alkyl groups are independently , or .

[0035] In one embodiment, R 1 and R 2 are independently H or -C(O)-R a , R a H or C 1-4 Alkyl; for example, R 1 and R 2 are independently H, -C(O)-H or -C(O)-CH3.

[0036] In one embodiment, the compound shown in formula I is or .

[0037] In one embodiment, in step S1, the purity of the compound of formula I is greater than 80%, for example, greater than 90%, for example, greater than 95%, for example, greater than 99%, for example, 99.5% or 99.7%.

[0038] In one embodiment, the compound as shown in formula II is selected from one or more of formic acid, acetic acid, propionic acid, butyric acid, trifluoroacetic acid, dichloroacetic acid, oxalic acid and lactic acid, for example, selected from one or more of formic acid, acetic acid, dichloroacetic acid, trifluoroacetic acid, lactic acid and propionic acid, for example, formic acid, acetic acid, dichloroacetic acid, trifluoroacetic acid, lactic acid or propionic acid.

[0039] In one embodiment, in step S1, the molar ratio of the compound represented by formula II to the compound represented by formula I is (10-1000):1, for example (100-500):1, for example 160:1, 200:1, 240:1, 280:1, 330:1, 390:1 or 400:1.

[0040] In one embodiment, in step S1, the compound represented by formula II is added dropwise into the reaction system of the reaction.

[0041] In one embodiment, in step S1, the aromatic hydrocarbon solvent is selected from one or both of toluene and xylene, such as toluene or xylene.

[0042] In one embodiment, in step S1, the halogenated alkane solvent is one or more of dichloromethane, chloroform, 1,1-dichloroethane and 1,2-dichloroethane, for example, one or both of dichloromethane and 1,2-dichloroethane; for example, dichloromethane or 1,2-dichloroethane.

[0043] In one embodiment, in step S1, the halogenated aromatic hydrocarbon solvent is chlorobenzene.

[0044] In one embodiment, in step S1, the alkane solvent is selected from one or more of cyclohexane, n-hexane, n-heptane, isoheptane, n-octane, isooctane and petroleum ether, for example, one or more of cyclohexane, n-hexane, n-heptane, n-octane, isooctane and petroleum ether; for example, cyclohexane, n-hexane, n-heptane, n-octane, isooctane or petroleum ether.

[0045] In one embodiment, in step S1, the volume ratio of the organic solvent A1 to the organic solvent A2 is (0.1-5):1, for example (0.1-3):1, for example 0.4:1, 0.5:1, 0.6:1 or 1:1.

[0046] In one embodiment, in step S1, the organic solvent is selected from any of the following combinations:

[0047] Combination 1: xylene and n-octane; for example, a volume ratio of 0.6:1 or 1:1;

[0048] Combination 2: xylene and cyclohexane; for example, the volume ratio is 0.4:1;

[0049] Combination 3: toluene and isooctane; for example, the volume ratio is 0.5:1;

[0050] Combination 4: chlorobenzene and n-heptane; for example, the volume ratio is 0.5:1;

[0051] Combination 5: chlorobenzene and n-octane; for example, the volume ratio is 0.5:1;

[0052] Combination 6: 1,2-dichloroethane and petroleum ether; for example, the volume ratio is 0.5:1;

[0053] Combination 7: dichloromethane and n-hexane; for example, the volume ratio is 0.4:1.

[0054] In one embodiment, in step S1, the molar volume ratio of the compound of formula I to the organic solvent is (0.01-1) mol:1L, for example (0.01-0.3) mol:1L, for example 0.06 mol:1L, 0.07 mol:1L, 0.08 mol:1L or 0.09 mol:1L.

[0055] In one embodiment, in step S1, the catalyst is selected from one or more of sulfuric acid, phosphoric acid, sodium bisulfate, p-toluenesulfonic acid, trifluoromethanesulfonic acid, zinc chloride, ferric chloride and calcium chloride; for example, sulfuric acid, phosphoric acid, sodium bisulfate, p-toluenesulfonic acid, trifluoromethanesulfonic acid, zinc chloride, ferric chloride or calcium chloride.

[0056] In one embodiment, in step S1, the molar ratio of the catalyst to the compound of formula I is (0.005-0.2):1, for example (0.01-0.1):1, for example 0.02:1, 0.03:1, 0.04:1, 0.05:1 or 0.08:1.

[0057] In one embodiment, in step S1, the weight ratio of the compound represented by formula I to the catalyst is 1:(0.005-0.02).

[0058] In one embodiment, in step S1, the reaction temperature is 0-100°C, such as 20-90°C, such as 25°C, 55°C, 60°C or 80°C.

[0059] In step S1, the progress of the reaction is monitored by a conventional monitoring method in the art (e.g., HPLC), and the reaction endpoint is when the compound shown in formula I disappears or no longer decreases. In one embodiment, the reaction time is 1-60 hours, such as 5 hours, 15 hours, 24 hours, or 48 hours.

[0060] In step S1, after the reaction is completed, a conventional post-treatment step of this type of reaction is further included, for example, the post-treatment step is standing and stratifying to remove the organic solvent in the organic solvent phase (to obtain the product). Preferably, the standing and stratifying is at 0-100°C, for example, 20-90°C, and for example, 25°C, 55°C, 60°C or 80°C.

[0061] In one embodiment, in step S2, the alcohol solvent is selected from one or more of methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, ethylene glycol and glycerol, for example, selected from one or more of methanol, ethanol, n-propanol, isopropanol and n-butanol, for example, methanol, ethanol, n-propanol, isopropanol or n-butanol; for example, methanol and / or ethanol.

[0062] In one embodiment, in step S2, the ketone solvent is acetone.

[0063] In one embodiment, in step S2, the alkane solvent is selected from one or more of n-hexane, n-heptane, n-octane, petroleum ether, cyclohexane, isoheptane and isooctane; for example, selected from one or more of cyclohexane, n-hexane and n-octane, such as cyclohexane, n-hexane or n-octane.

[0064] In one embodiment, in step S2, the aromatic hydrocarbon solvent is selected from one or both of toluene and xylene, such as toluene or xylene.

[0065] In one embodiment, in step S2, the organic solvent B1 is an alcohol solvent.

[0066] In one embodiment, in step S2, the organic solvent is selected from any of the following combinations:

[0067] Combination A: methanol and n-octane;

[0068] Combination B: ethanol and xylene;

[0069] Combination C: n-propanol and toluene;

[0070] Combination D: isopropyl alcohol and n-octane;

[0071] Combination E: n-butanol and cyclohexane;

[0072] Combination F: ethanol and n-hexane;

[0073] Combination G: methanol and toluene.

[0074] In one embodiment, in step S2, the volume ratio of the organic solvent B1 to the organic solvent B2 is (0.5-3):1, for example (1-2):1, and for example 1.25:1 or 1.6:1.

[0075] In one embodiment, in step S2, the mass volume ratio of the product in step S1 to the organic solvent is (50-500) g:1 L, for example (150-350) g:1 L, for example 190 g:1 L, 200 g:1 L or 290 g:1 L.

[0076] In one embodiment, in step S2, the base is an inorganic base, such as an alkali metal hydroxide, such as one or more selected from sodium hydroxide, potassium hydroxide and lithium hydroxide, such as sodium hydroxide, potassium hydroxide or lithium hydroxide.

[0077] In one embodiment, in step S2, the mass ratio of the base to the product in step S1 is (0.05-0.5):1, for example (0.1-0.4):1, for example 0.1:1, 0.2:1 or 0.3:1.

[0078] In one embodiment, the saponification reaction temperature is -15°C to 80°C, such as -5°C to 50°C, such as 25°C.

[0079] In step S2, the progress of the reaction is monitored by conventional monitoring methods in the art (such as HPLC), and the end point of the reaction is when the product in step S1 disappears or no longer decreases. In one embodiment, the saponification reaction time is 0.5-10h, such as 1-5h, and for example 3h.

[0080] In one embodiment, in step S2, the acid is an inorganic acid, such as HCl, and for example, the HCl is added to the neutralization reaction system in the form of a 32 wt % hydrochloric acid aqueous solution.

[0081] The amount of the acid used in step S2 is sufficient to neutralize the alkali remaining after the saponification reaction. The pH of the reaction system after the neutralization reaction is 6.5-7.5, for example 7.

[0082] In step S2, after the neutralization reaction is completed, a conventional post-treatment step for such a reaction in the art is further included, such as removing the solvent (to obtain a saponification product).

[0083] In one embodiment, in step S3, the organic solvent is selected from one or more of alkane solvents, ester solvents and benzene solvents, for example, one or two of alkane solvents and benzene solvents, such as alkane solvents or benzene solvents.

[0084] In one embodiment, in step S3, the alkane solvent is selected from one or more of n-hexane, n-heptane, n-octane, petroleum ether, cyclohexane, isoheptane and isooctane, for example, one or more of n-octane, n-heptane and petroleum ether, for example, n-octane, n-heptane or petroleum ether.

[0085] In one embodiment, in step S3, the benzene solvent is selected from one or both of toluene and xylene, such as toluene or xylene.

[0086] In one embodiment, in step S3, the ester solvent is ethyl acetate.

[0087] In step S3, the amount of the organic solvent used is sufficient to completely dissolve the saponified product. In one embodiment, the mass volume ratio of the saponified product to the organic solvent is 1 g: (4-20) ml, such as 1 g: (5-10) ml, or 1 g: 7 ml or 1 g: 8 ml.

[0088] In step S3, the amount of water used is sufficient to completely remove the salt in the saponification product. In one embodiment, the mass volume ratio of the saponification product to the water is 1 g: (0.5-5) ml, for example 1 g: (1-3) ml, and for example 1 g: 2 ml.

[0089] In one embodiment, in step S3, the dissolving temperature is 40-100°C, such as 50-90°C, and for example 80°C.

[0090] In one embodiment, in step S3, the water washing temperature is 50-80°C, such as 60°C or 80°C.

[0091] Step S3 also includes post-treatment steps of standing for stratification and removing the solvent in the organic phase.

[0092] In one embodiment, in step S4, the organic solvent is selected from one or both of ketone solvents and alcohol solvents, for example, a ketone solvent or an alcohol solvent.

[0093] In one embodiment, in step S4, the ketone solvent is acetone.

[0094] In one embodiment, in step S4, the alcohol solvent is one or more of methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, ethylene glycol and glycerol, for example, one or more selected from methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol and ethylene glycol; for example, methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol or ethylene glycol.

[0095] In one embodiment, in step S4, the mass volume ratio of the crude product 1 to the organic solvent is 1 g: (4-60) ml, for example, 1 g: 10 ml, 1 g: 21 ml, 1 g: 31 ml, 1 g: 41 ml or 1 g: 51 ml.

[0096] In one embodiment, in step S4, the dissolving temperature is 50°C, 64°C, 75°C or 80°C.

[0097] In one embodiment, in step S4, the crystallization temperature is 20-25°C, for example 20°C.

[0098] In one embodiment, in step S4, the cooling rate is 10-25°C / h.

[0099] In step S4, after the crystallization is completed, a post-processing step of filtering and removing the solvent may be further included.

[0100] In one embodiment, the operation and conditions of step S5 are as described in any scheme of step S4.

[0101] On the basis of being in accordance with the common sense in the art, the above-mentioned preferred conditions can be arbitrarily combined to obtain the preferred embodiments of the present invention.

[0102] The positive and progressive effects of the present invention are that the reagents and raw materials used in the present invention are all commercially available, especially the 25-hydroxycholesterol prepared according to patent CN113185565 A, which has low cost, high content and easy to obtain raw materials.

[0103] The method for preparing high-purity 24-dehydrocholesterol provided by the present invention has the advantages of simple synthesis method, high purity, suitability for large-scale preparation and safety. DETAILED DESCRIPTION

[0104] The present invention is further described below by way of examples, but the present invention is not limited to the scope of the examples. The experimental methods in the following examples without specifying specific conditions are carried out according to conventional methods and conditions, or selected according to the product specifications.

[0105] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0106] In the following examples, the content was measured by high performance liquid chromatography (the high performance liquid chromatography detection method was in accordance with the cholesterol liquid chromatography detection method formulated in the Pharmacopoeia of the People's Republic of China (Volume II 2020 Edition))

[0107] Embodiment 1:

[0108]

[0109] 50.0 g (content: 99.5%, 123.7 mmol) of 25-hydroxycholesterol was added to a 10 L three-necked flask, and dissolved in 600 mL of xylene, 0.25 g of sulfuric acid was added, 1000 ml of n-octane was added, and then 4500 g (50 mol) of lactic acid was added dropwise under stirring for 0.5 h. After the elimination reaction was carried out under stirring at 55 ° C for 5 h, HPLC was used to track the reaction until 25-hydroxycholesterol no longer decreased; under 55 ° C, stirring was stopped and the mixture was allowed to stand for stratification to obtain an n-octane phase and a residual acid phase, wherein the residual acid phase can be further used for the elimination reaction, and the n-octane phase was evaporated to dryness to obtain 51.5 g of an eliminated product, and 16.8 g (300 mmol) of potassium hydroxide, 160 mL of methanol, 100 mL of n-octane and 100 mL of ethanol were added to the eliminated product in sequence. 00mL, react at 25℃ for 3h, and track the reaction by HPLC until the reaction is complete; add 32wt% hydrochloric acid solution to the system after the saponification reaction to adjust the pH to 7, then evaporate to dryness to obtain 69.7g of saponification product, cool to below 80℃, add 500mL of n-octane to the saponification product, wash and remove salt at 60℃ with 150mL of water, evaporate the n-octane phase under reduced pressure to obtain 48.9g, then add 2500ml of methanol, heat to 64℃ and dissolve until the solution is clear, control the temperature to 20-25℃ for 3 hours to crystallize, filter to obtain crude 24-dehydrocholesterol, and then recrystallize with 2500mL of methanol (the recrystallization operation is carried out with reference to the first crystallization), and obtain 24.5g (63.8mmol) of 24-dehydrocholesterol with a content of 99.4%.

[0110] Compound (24-dehydrocholesterol) characterization:

[0111] Melting point: 119-121.5℃;

[0112] 1 H-NMR (TMS, CDCl3, 400MHz):δ H 5.34(m,1H),5.08(t,1H),3.52(m,1H),2.25(m,2H),1.99(m,3H),1.83(m,4H),1.70(m,1H),1.68( s,3H),1.60(s,3H),1.32-1.58(m,8H),1.01-1.31(m,7H),1.00(s,3H),0.93(d,3H),0.68(s,3H);

[0113] 13 C-NMR (TMS,CDCl3,400MHz): δ C140.89,131.04,125.35,121.83,71.90,56.88,56.20,50.25,42.47,42.41,39.90,37.38,36.63,36.22,35.73,32.03,32.03,31.77,28.34,25.86,24.85,24.43,21.21,19.53,18.76,17.77,11.99;

[0114] HRESIMS m / z 385.6[M+H] + .

[0115] Example 2

[0116]

[0117] 50.0 g (content: 99.7%, 102.5 mmol) of 25-hydroxycholesterol diacetyl ester was added to a 10 L three-necked flask, dissolved in 500 mL of chlorobenzene, 0.5 g of phosphoric acid was added, 1000 mL of n-heptane was added, and then 3600 g (40 mol) of acetic acid was added dropwise under stirring for 0.5 h. After the elimination reaction was carried out under stirring at 80 ° C for 24 h, HPLC tracking of the reaction was performed until the 25-hydroxycholesterol diacetyl ester no longer decreased; under 80 ° C, the mixture was allowed to stand for stratification to obtain an n-heptane phase and a residual acid phase, wherein the residual acid phase can be further used for the elimination reaction, the obtained n-heptane phase was evaporated to dryness to obtain 50.8 g of an eliminated product, 12.0 g (300 mmol) of sodium hydroxide and 12.0 g (300 mmol) of sodium hydroxide were added to the eliminated product in sequence. l), 160mL of ethanol and 100mL of xylene, react at 25°C for 3h, and track the reaction by HPLC until the reaction is complete; add 32wt% hydrochloric acid solution to the system after the saponification reaction to adjust the pH to 7, then evaporate to dryness to obtain 68.6g of saponification product, cool to 80°C, add 500mL of n-heptane to the saponification product, wash with water at 60°C to remove salt, evaporate to dryness under reduced pressure to obtain 49.1g, then add 2000ml of ethanol, heat to 75°C to dissolve, cool to 20°C to crystallize, filter to obtain crude 24-dehydrocholesterol, and then recrystallize with 2000mL of ethanol (the recrystallization operation is carried out with reference to the first crystallization), and obtain 20.5g (53.3mmol) of 24-dehydrocholesterol with a content of 99.5%.

[0118] The compound characterization results showed that it was 24-dehydrocholesterol.

[0119] Example 3

[0120]

[0121] 50.0 g (content: 99.7%, 108.8 mmol) of 25-hydroxycholesterol diformyl ester was added to a 10 L three-necked flask, dissolved with 500 mL of 1,2-dichloroethane, 1.0 g of sodium bisulfate was added, 1000 mL of petroleum ether was added, and then 1380 g (30 mol) of formic acid was added dropwise under stirring for 0.5 h. After the elimination reaction was carried out under stirring at 60 ° C for 48 h, HPLC was used to track the reaction until the 25-hydroxycholesterol diformyl ester no longer decreased; at 60 ° C, the mixture was allowed to stand for stratification to obtain a petroleum ether phase and a residual acid phase, wherein the residual acid phase can be further used for the elimination reaction, and the obtained petroleum ether phase was evaporated to dryness to obtain 50.5 g of an eliminated product, and 7.2 g (300 mmol) of lithium hydroxide were added to the eliminated product in sequence. , 160mL of n-propanol, and 100mL of toluene, react at 25°C for 3h, and track the reaction by HPLC until the reaction is complete; add 32wt% hydrochloric acid solution to the system after the saponification reaction to adjust the pH to 7, then evaporate to dryness to obtain 63.8g of saponification product, cool to 80°C, add 500mL of petroleum ether to the saponification product, wash with water at 60°C to remove salt, the amount of water used is 100mL, evaporate to dryness under reduced pressure to obtain 49.0g, then add 1500ml of n-propanol, heat to 80°C to dissolve, cool to 20°C to crystallize, filter to obtain crude 24-dehydrocholesterol, and then recrystallize with 1500mL of n-propanol (the recrystallization operation is carried out with reference to the first crystallization), to obtain 21.9g (57.0mmol) of 24-dehydrocholesterol, with a content of 99.6%.

[0122] The compound characterization results showed that it was 24-dehydrocholesterol.

[0123] Example 4

[0124] 50.0 g (content: 99.5%, 123.7 mmol) of 25-hydroxycholesterol was added to a 10 L three-necked flask and dissolved in 500 mL of toluene, 0.75 g of p-toluenesulfonic acid and 1000 ml of isooctane were added, and then 2220 g (30 mol) of propionic acid was added dropwise under stirring for 0.5 h. After the elimination reaction was carried out under stirring at 55 ° C for 15 h, HPLC was used to track the reaction until 25-hydroxycholesterol no longer decreased; under 55 ° C, stirring was stopped and the mixture was allowed to stand for stratification to obtain an isooctane phase and a residual acid phase, wherein the residual acid phase can be further used for the elimination reaction, and the isooctane phase was evaporated to dryness to obtain 51.9 g of an eliminated product, and 16.8 g (300 mmol) of potassium hydroxide, 1000 ml of isooctane and 1000 ml of isooctane were added to the eliminated product in sequence. 60mL, 100mL of n-octane, react at 25℃ for 3h, and track the reaction by HPLC until the reaction is complete; add 32wt% hydrochloric acid solution to the system after the saponification reaction to adjust the pH to 7, then evaporate to dryness to obtain 73.5g of saponification product, cool to 80℃, add 500mL of toluene to the saponification product, wash with water at 60℃ to remove salt, the amount of water is 150mL, evaporate to dryness under reduced pressure to obtain 48.7g, then add 1500ml of isopropanol, heat to 80℃ to dissolve, cool to 20℃ to crystallize, filter to obtain crude 24-dehydrocholesterol, and then recrystallize with 1500mL of isopropanol (the recrystallization operation is carried out with reference to the first crystallization), and obtain 25.2g (65.6mmol) of 24-dehydrocholesterol with a content of 99.2%.

[0125] The compound characterization results showed that it was 24-dehydrocholesterol.

[0126] Example 5

[0127] 50.0 g (content: 99.5%, 123.7 mmol) of 25-hydroxycholesterol was added to a 10 L three-necked flask, and dissolved in 386 mL of xylene, 0.5 g of trifluoromethanesulfonic acid was added, 1000 mL of cyclohexane was added, and then 3225 g (25 mol) of dichloroacetic acid was added dropwise under stirring for 0.5 h. After 24 h of elimination reaction under stirring at 25 ° C, HPLC tracking reaction was performed until 25-hydroxycholesterol no longer decreased; under 25 ° C conditions, stirring was stopped and the mixture was allowed to stand for stratification to obtain a cyclohexane phase and a residual acid phase, wherein the residual acid phase can be further used for elimination reaction, the cyclohexane phase was evaporated to dryness to obtain 51.4 g of eliminated product, 16.8 g (300 m mol), 160mL of n-butanol and 100mL of cyclohexane, react at 25°C for 3h, and track the reaction by HPLC until the reaction is complete; add 32wt% hydrochloric acid solution to the system after the saponification reaction to adjust the pH to 7, then evaporate to dryness to obtain 73.3g of a saponification product, cool to 80°C, add 500mL of xylene to the saponification product, wash with water at 80°C to remove salt, use 150mL of water, evaporate to dryness under reduced pressure to obtain 48.4g, then add 1000ml of n-butanol, heat to 80°C to dissolve, cool to 20°C to crystallize, filter to obtain a crude 24-dehydrocholesterol, and then recrystallize with 1000mL of n-butanol to obtain 28.5g (74.2mmol) of 24-dehydrocholesterol with a content of 99.2%.

[0128] The compound characterization results showed that it was 24-dehydrocholesterol.

[0129] Example 6

[0130] 50.0 g (content: 99.5%, 123.7 mmol) of 25-hydroxycholesterol was added to a 10 L three-necked flask, and dissolved with 386 mL of dichloromethane, 0.5 g of zinc chloride was added, 1000 mL of n-hexane was added, and then 2280 g (20 mol) of trifluoroacetic acid was added dropwise under stirring for 0.5 h. After 24 h of elimination reaction under stirring at 25 ° C, HPLC was used to track the reaction until 25-hydroxycholesterol no longer decreased; under 25 ° C, stirring was stopped and the mixture was allowed to stand for stratification to obtain a n-hexane phase and a residual acid phase, wherein the residual acid phase can be further used for the elimination reaction, and the n-hexane phase was evaporated to dryness to obtain 51.8 g of an eliminated product, and 16.8 g (300 mmol) of potassium hydroxide, ethanol and the like were added to the eliminated product in sequence. 100mL, 80mL of n-hexane, react at 25℃ for 3h, and track the reaction by HPLC until the reaction is complete; add 32wt% hydrochloric acid solution to the system after the saponification reaction to adjust the pH to 7, then evaporate to dryness to obtain 73.8g of saponification product, cool to 80℃, add 600mL of toluene to the saponification product, wash and remove salt at 80℃ with 150mL of water, evaporate to dryness under reduced pressure to obtain 48.3g, then add 1000ml of isobutanol, heat to 80℃ to dissolve, cool to 20℃ to crystallize, filter to obtain crude 24-dehydrocholesterol, and then recrystallize with 1000mL of isobutanol (the recrystallization operation is carried out with reference to the first crystallization), and obtain 28.1g (73.1mmol) of 24-dehydrocholesterol with a content of 99.2%.

[0131] The compound characterization results showed that it was 24-dehydrocholesterol.

[0132] Example 7

[0133] 50.0 g (content: 99.5%, 123.7 mmol) of 25-hydroxycholesterol was added to a 10 L three-necked flask, and dissolved in 500 mL of chlorobenzene, 0.5 g of ferric chloride was added, 1000 mL of n-octane was added, and then 1800 g (30 mol) of acetic acid was added dropwise under stirring for 0.5 h. After 24 h of elimination reaction under stirring at 60 ° C, HPLC tracking of the reaction was performed until 25-hydroxycholesterol no longer decreased; under 60 ° C, stirring was stopped and the mixture was allowed to stand for stratification to obtain an n-octane phase and a residual acid phase, wherein the residual acid phase can be further used for the elimination reaction, and the n-octane phase was evaporated to dryness to obtain 51.3 g of an eliminated product, and 16.8 g (300 mmol) of potassium hydroxide, methanol and the like were added to the eliminated product in sequence. 160mL, 100mL toluene, react at 25℃ for 3h, and track the reaction by HPLC until the reaction is complete; add 32wt% hydrochloric acid solution to the system after the saponification reaction to adjust the pH to 7, then evaporate to dryness to obtain 73.0g of saponification product, cool to 80℃, add 500mL n-octane to the saponification product, wash with water at 60℃ to remove salt, the amount of water is 150mL, evaporate to dryness under reduced pressure to obtain 48.2g, then add 500ml of ethylene glycol, heat to 80℃ to dissolve, cool to 20℃ to crystallize, filter to obtain crude 24-dehydrocholesterol, and then recrystallize with 500mL ethylene glycol (the recrystallization operation is carried out with reference to the first crystallization), and obtain 30.1g (78.3mmol) of 24-dehydrocholesterol with a content of 99.2%.

[0134] The compound characterization results showed that it was 24-dehydrocholesterol.

[0135] Example 8

[0136] 50.0 g (content: 99.5%, 123.7 mmol) of 25-hydroxycholesterol was added to a 10 L three-necked flask and dissolved in 1000 mL of xylene, 0.5 g of calcium chloride and 1000 mL of n-octane were added, and then 4500 g (50 mol) of lactic acid was added dropwise under stirring for 0.5 h. After 24 h of elimination reaction under stirring at 55 ° C, HPLC was used to track the reaction until 25-hydroxycholesterol no longer decreased. Under 55 ° C, stirring was stopped and the mixture was allowed to stand for stratification to obtain an n-octane phase and a residual acid phase, wherein the residual acid phase could be further used for the elimination reaction. The n-octane phase was evaporated to dryness to obtain 52.1 g of an eliminated product, and 16.8 g (300 mmol) of potassium hydroxide, 160mL of methanol and 100mL of toluene were reacted at 25℃ for 3h, and the reaction was followed by HPLC until the reaction was complete; 32wt% hydrochloric acid solution was added dropwise to the system after the saponification reaction to adjust the pH to 7, and then evaporated to obtain 73.8g of saponification product, cooled to 80℃, 500mL of toluene was added to the saponification product, and washed with water at 80℃ to remove salt, the amount of water was 150mL, and 48.3g was evaporated under reduced pressure, and then 500ml of acetone was added, the temperature was raised to 50℃ to dissolve, the temperature was lowered to 20℃ to crystallize, and the crude 24-dehydrocholesterol was filtered, and then recrystallized with 500mL of acetone (the recrystallization operation was carried out with reference to the first crystallization), and 30.1g (78.3mmol) of 24-dehydrocholesterol was obtained, with a content of 99.2%.

[0137] The compound characterization results showed that it was 24-dehydrocholesterol.

[0138] Comparative Example 1 (elimination reaction without adding the second solvent)

[0139] 50.0 g (content: 99.5%, 123.7 mmol) of 25-hydroxycholesterol was added to a 10 L three-necked flask and dissolved in 600 mL of xylene. 0.25 g of sulfuric acid was added, and then 4500 g (50 mol) of lactic acid was added dropwise under stirring for 0.5 h. After the elimination reaction was carried out under stirring at 55° C. for 5 h, HPLC was used to track the reaction until 25-hydroxycholesterol no longer decreased. Under the condition of 55° C., 1000 ml of n-octane was added for extraction and stratification to obtain an n-octane phase and a residual acid phase. The n-octane phase was evaporated to dryness to obtain 50.5 g of an eliminated product. 16.8 g (300 mmol) of potassium hydroxide, 160 mL of methanol, 100 g of n-octane and 100 g of n-octane were added to the eliminated product in sequence. mL, react at 25°C for 3h, and track the reaction by HPLC until the reaction is complete; add 32wt% hydrochloric acid solution to the system after the saponification reaction to adjust the pH to 7, then evaporate to dryness to obtain 72.8g of saponification product, cool to 80°C, add 500mL of n-octane to the saponification product, wash with water at 60°C to remove salt, the amount of water used is 150mL, evaporate to dryness under reduced pressure to obtain 49.7g, then add 2500ml of methanol, heat to 64°C to dissolve, cool to 20°C to crystallize, filter to obtain crude 24-dehydrocholesterol, and then recrystallize with 2500mL of methanol (the recrystallization operation is carried out with reference to the first crystallization), to obtain 5.5g (14.3mmol) of 24-dehydrocholesterol with a content of 94.4%.

[0140] Comparative Example 2 (elimination reaction without adding the first solvent)

[0141] 50.0 g (content: 99.5%, 123.7 mmol) of 25-hydroxycholesterol was added to a 10 L three-necked flask, 1000 ml of n-octane was added, 0.25 g of sulfuric acid was added, and then 4500 g (50 mol) of lactic acid was added dropwise under stirring for 0.5 h. After the elimination reaction was carried out under stirring at 55 ° C for 5 h, HPLC was used to track the reaction until 25-hydroxycholesterol no longer decreased. Under 55 ° C, stirring was stopped and the mixture was allowed to stand for stratification to obtain an n-octane phase and a residual acid phase. The n-octane phase was evaporated to dryness to obtain 52.3 g of an eliminated product. 16.8 g (300 mmol) of potassium hydroxide, 160 mL of methanol, 100 mL of n-octane, 25 ℃ after 3h reaction, HPLC tracking reaction until the reaction is complete; 32wt% hydrochloric acid solution is added dropwise to the system after saponification reaction to adjust pH to 7, then evaporated to obtain 72.7g of saponification product, cooled to 80℃, added 500mL of n-octane to the saponification product, washed with water at 60℃ to remove salt, the amount of water used is 150mL, evaporated to dryness under reduced pressure to obtain 49.9g, then added 2500ml of methanol, heated to 64℃ to dissolve, cooled to 20℃ to crystallize, filtered to obtain crude 24-dehydrocholesterol, and then recrystallized with 2500mL of methanol (recrystallization operation refers to the first crystallization), to obtain 0.5g (1.3mmol) of 24-dehydrocholesterol, with a content of 90.1%.

[0142] Comparative Example 3 (the first solvent of the elimination reaction is replaced by an alcohol, such as n-propanol)

[0143] 50.0 g (content: 99.5%, 123.7 mmol) of 25-hydroxycholesterol was added to a 10 L three-necked flask, and dissolved in 1600 mL of n-propanol, 0.25 g of sulfuric acid was added, 1000 ml of n-octane was added, and then 4500 g (50 mol) of lactic acid was added dropwise under stirring for 0.5 h. After the elimination reaction was carried out under stirring at 55 ° C for 5 h, HPLC was used to track the reaction until 25-hydroxycholesterol no longer decreased; under 55 ° C, stirring was stopped and the mixture was allowed to stand for stratification to obtain an n-octane phase and a residual acid phase, and the n-octane phase was evaporated to dryness to obtain 52.8 g of an eliminated product, and 16.8 g (300 mmol) of potassium hydroxide, 160 mL of methanol, 1000 ml of n-octane and 1000 ml of ethanol were added to the eliminated product in sequence. 00mL, react at 25℃ for 3h, and track the reaction by HPLC until the reaction is complete; add 32wt% hydrochloric acid solution to the system after the saponification reaction to adjust the pH to 7, then evaporate to dryness to obtain 72.7g of saponification product, cool to 80℃, add 500mL of n-octane to the saponification product, wash with water at 60℃ to remove salt, the amount of water is 150mL, evaporate to dryness under reduced pressure to obtain 49.9g, then add 2500ml of methanol, heat to 64℃ to dissolve, cool to 20℃ to crystallize, filter to obtain crude 24-dehydrocholesterol, and then recrystallize with 2500mL of methanol (the recrystallization operation is carried out with reference to the first crystallization), and obtain 0.6g (1.56mmol) of 24-dehydrocholesterol with a content of 84.7%.

[0144] Comparative Example 4 (without catalyst)

[0145] 50.0 g (content: 99.5%, 123.7 mmol) of 25-hydroxycholesterol was added to a 10 L three-necked flask and dissolved in 600 mL of xylene. Then, 4500 g (50 mol) of lactic acid was added dropwise under stirring for 0.5 h. After 24 h of elimination reaction under stirring at 55° C., HPLC was used to track the reaction until 25-hydroxycholesterol no longer decreased. Under 55° C., 1000 ml of n-octane was added for extraction and stratification to obtain an n-octane phase and a residual acid phase. The n-octane phase was evaporated to dryness to obtain 52.4 g of an eliminated product. 16.8 g (300 mmol) of potassium hydroxide, 160 mL of methanol, 100 mL of n-octane were added to the eliminated product in sequence. The mixture was stirred for 24 h at 55° C. and the mixture was stirred for 24 h ... ℃ after 3h reaction, HPLC tracking reaction until the reaction is complete; 32wt% hydrochloric acid solution is added dropwise to the system after saponification reaction to adjust pH to 7, then evaporated to obtain 73.0g of saponification product, cooled to 80℃, added 500mL of n-octane to the saponification product, washed with water at 60℃ to remove salt, the amount of water used was 150mL, evaporated to dryness under reduced pressure to obtain 49.6g, then added 2500ml of methanol, heated to 64℃ to dissolve, cooled to 20℃ to crystallize, filtered to obtain crude 24-dehydrocholesterol, and then recrystallized with 2500mL of methanol (recrystallization operation refers to the first crystallization), to obtain 7.5g (19.5mmol) of 24-dehydrocholesterol, with a content of 90.2%.

[0146] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for preparing high-purity 24-dehydrocholesterol, characterized in that: It includes the following steps: S1: reacting the compound represented by formula I in the presence of a catalyst and a compound represented by formula II in an organic solvent to obtain a product; ； in, R 1 and R 2 are independently H or -C(O)-R a , R a H, C 1-4 Alkyl, -C(O)-OH or one or more R a1 Substituted C 1-4 alkyl; R 3 -C(O)-R a , R a H, C 1-4 Alkyl, -C(O)-OH or one or more R a1 Substituted C 1-4 alkyl; R a1 are independently halogen or hydroxy; In step S1, the organic solvent is composed of an organic solvent A1 and an organic solvent A2, the organic solvent A1 is selected from one or more of an aromatic hydrocarbon solvent, a halogenated alkane solvent and a halogenated aromatic hydrocarbon solvent, and the organic solvent A2 is an alkane solvent; In step S1, the catalyst is selected from one or more of sulfuric acid, phosphoric acid, p-toluenesulfonic acid, trifluoromethanesulfonic acid, sodium bisulfate, potassium bisulfate, zinc chloride, ferric chloride, titanium tetrachloride, aluminum chloride and calcium chloride; S2: Under the action of a base, the product in step S1 is subjected to a saponification reaction in an organic solvent; and then subjected to a neutralization reaction with an acid to obtain a saponification product; In step S2, the organic solvent consists of an organic solvent B1 and an organic solvent B2, the organic solvent B1 is selected from one or both of an alcohol solvent and a ketone solvent, and the organic solvent B2 is selected from one or both of an alkane solvent and an aromatic solvent; S3: using an organic solvent to dissolve the saponification product, and then washing the saponification product solution with water at 40° C.-80° C. to obtain a crude product 1 of 24-dehydrocholesterol; S4: mixing the crude product 1 with an organic solvent to dissolve at 40-90° C.; then cooling to 10-30° C. to crystallize, to obtain a crude product 2 of 24-dehydrocholesterol; S5: Mix the crude product 2 with an organic solvent to dissolve it at 40-90° C.; then cool it to 10-30° C. to recrystallize it to obtain 24-dehydrocholesterol.

2. The method for preparing high-purity 24-dehydrocholesterol according to claim 1, characterized in that: Step S1 satisfies one or more of the following conditions: (1) The halogen is fluorine, chlorine, bromine or iodine, for example fluorine or chlorine; (2) The one or more R a1 Substituted C 1-4 The alkyl groups are independently , or ; (3) The compound represented by formula II is selected from one or more of formic acid, acetic acid, propionic acid, butyric acid, trifluoroacetic acid, dichloroacetic acid, oxalic acid and lactic acid, for example, selected from one or more of formic acid, acetic acid, dichloroacetic acid, trifluoroacetic acid, lactic acid and propionic acid, for example, formic acid, acetic acid, dichloroacetic acid, trifluoroacetic acid, lactic acid or propionic acid; (4) The molar ratio of the compound of formula II to the compound of formula I is (10-1000):1, for example (100-500):1, for example 160:1, 200:1, 240:1, 280:1, 330:1, 390:1 or 400:1; (5) adding the compound represented by formula II dropwise into the reaction system; (6) The aromatic hydrocarbon solvent is selected from one or both of toluene and xylene, such as toluene or xylene; (7) The halogenated alkane solvent is one or more of dichloromethane, chloroform, 1,1-dichloroethane and 1,2-dichloroethane, for example, one or two selected from dichloromethane and 1,2-dichloroethane; for example, dichloromethane or 1,2-dichloroethane; (8) The halogenated aromatic hydrocarbon solvent is chlorobenzene; (9) The alkane solvent is selected from one or more of cyclohexane, n-hexane, n-heptane, isoheptane, n-octane, isooctane and petroleum ether, for example, one or more of cyclohexane, n-hexane, n-heptane, n-octane, isooctane and petroleum ether; for example, cyclohexane, n-hexane, n-heptane, n-octane, isooctane or petroleum ether; (10) The volume ratio of the organic solvent A1 to the organic solvent A2 is (0.1-5):1, for example (0.1-3):1, for example 0.4:1, 0.5:1, 0.6:1 or 1:1; (11) The molar volume ratio of the compound of formula I to the organic solvent is (0.01-1) mol:1L, for example (0.01-0.3) mol:1L, for example 0.06 mol:1L, 0.07 mol:1L, 0.08 mol:1L or 0.09 mol:1L; (12) The catalyst is selected from one or more of sulfuric acid, phosphoric acid, sodium bisulfate, p-toluenesulfonic acid, trifluoromethanesulfonic acid, zinc chloride, ferric chloride and calcium chloride; for example, sulfuric acid, phosphoric acid, sodium bisulfate, p-toluenesulfonic acid, trifluoromethanesulfonic acid, zinc chloride, ferric chloride or calcium chloride; (13) The molar ratio of the catalyst to the compound of formula I is (0.005-0.2):1, for example (0.01-0.1):1, for example 0.02:1, 0.03:1, 0.04:1, 0.05:1 or 0.08:1; (14) In step S1, the reaction temperature is 0-100°C, for example, 20-90°C, for example, 25°C, 55°C, 60°C or 80°C; (15) After the reaction is completed, a post-treatment step is further included, wherein the post-treatment step is to allow the organic solvent to stand for stratification and remove the organic solvent from the organic solvent phase; preferably, the stratification is performed at 0-100°C, such as 20-90°C, and also at 25°C, 55°C, 60°C or 80°C.

3. The method for preparing high-purity 24-dehydrocholesterol according to claim 2, characterized in that: Step S1 satisfies one or more of the following conditions: (1) R 1 and R 2 are independently H or -C(O)-R a , R a H or C 1-4 Alkyl; for example, R 1 and R 2 are independently H, -C(O)-H or -C(O)-CH3; (2) The purity of the compound of formula I is 80% or more, for example, 90% or more, for example, 95% or more, for example, 99% or more, for example, 99.5% or 99.7%; (3) The organic solvent is selected from any of the following combinations: Combination 1: xylene and n-octane; for example, a volume ratio of 0.6:1 or 1:1; Combination 2: xylene and cyclohexane; for example, the volume ratio is 0.4:1; Combination 3: toluene and isooctane; for example, the volume ratio is 0.5:1; Combination 4: chlorobenzene and n-heptane; for example, the volume ratio is 0.5:1; Combination 5: chlorobenzene and n-octane; for example, the volume ratio is 0.5:1; Combination 6: 1,2-dichloroethane and petroleum ether; for example, the volume ratio is 0.5:1; Combination 7: dichloromethane and n-hexane; for example, the volume ratio is 0.4:

1.

4. The method for preparing high-purity 24-dehydrocholesterol according to claim 1, characterized in that: The compound shown in formula I is: or .

5. The method for preparing high-purity 24-dehydrocholesterol according to any one of claims 1 to 4, characterized in that: Step S2 satisfies one or more of the following conditions: (1) The alcohol solvent is selected from one or more of methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, ethylene glycol and glycerol, for example, one or more of methanol, ethanol, n-propanol, isopropanol and n-butanol, for example, methanol, ethanol, n-propanol, isopropanol or n-butanol; (2) The ketone solvent is acetone; (3) The alkane solvent is selected from one or more of n-hexane, n-heptane, n-octane, petroleum ether, cyclohexane, isoheptane and isooctane; for example, selected from one or more of cyclohexane, n-hexane and n-octane, such as cyclohexane, n-hexane or n-octane; (4) The aromatic hydrocarbon solvent is selected from one or both of toluene and xylene, such as toluene or xylene; (5) The volume ratio of the organic solvent B1 to the organic solvent B2 is (0.5-3):1, for example (1-2):1, for example 1.25:1 or 1.6:1; (6) The mass volume ratio of the product in step S1 to the organic solvent is (50-500) g:1 L, for example (150-350) g:1 L, for example 190 g:1 L, 200 g:1 L or 290 g:1 L; (7) The base is an inorganic base, such as an alkali metal hydroxide, such as one or more selected from sodium hydroxide, potassium hydroxide and lithium hydroxide, such as sodium hydroxide, potassium hydroxide or lithium hydroxide; (8) The mass ratio of the base to the product in step S1 is (0.05-0.5):1, for example (0.1-0.4):1, for example 0.1:1, 0.2:1 or 0.3:1; (9) The temperature of the saponification reaction is -15°C to 80°C, for example -5°C to 50°C, for example 25°C; (10) The acid is an inorganic acid, such as HCl, and for example, the HCl is added to the neutralization reaction system in the form of a 32 wt % hydrochloric acid aqueous solution; (11) After the neutralization reaction is completed, the pH of the reaction system is 6.5-7.5, for example 7; (12) After the neutralization reaction is completed, a post-treatment step of removing the solvent is also included.

6. The method for preparing high-purity 24-dehydrocholesterol according to claim 5, characterized in that: In step S2, the organic solvent B1 is an alcohol solvent; Preferably, in step S2, the organic solvent is selected from any one of the following combinations: Combination A: methanol and n-octane; Combination B: ethanol and xylene; Combination C: n-propanol and toluene; Combination D: isopropyl alcohol and n-octane; Combination E: n-butanol and cyclohexane; Combination F: ethanol and n-hexane; Combination G: methanol and toluene.

7. The method for preparing high-purity 24-dehydrocholesterol according to any one of claims 1 to 4, characterized in that: Step S3 satisfies one or more of the following conditions: (1) The organic solvent is selected from one or more of an alkane solvent, an ester solvent and a benzene solvent, for example, one or two of an alkane solvent and a benzene solvent, for example, an alkane solvent or a benzene solvent; Preferably, the alkane solvent is selected from one or more of n-hexane, n-heptane, n-octane, petroleum ether, cyclohexane, isoheptane and isooctane, for example, selected from one or more of n-octane, n-heptane and petroleum ether, for example, n-octane, n-heptane or petroleum ether; The benzene solvent may be selected from one or both of toluene and xylene, such as toluene or xylene; The ester solvent may be ethyl acetate; (2) The mass volume ratio of the saponification product to the organic solvent is 1 g: (4-20) ml, for example 1 g: (5-10) ml, for example 1 g: 7 ml or 1 g: 8 ml; (3) The mass volume ratio of the saponification product to the water is 1 g: (0.5-5) ml, for example 1 g: (1-3) ml, and for example 1 g: 2 ml; (4) The dissolving temperature is 40-100°C, for example 50-90°C, for example 80°C; (5) The water washing temperature is 50-80°C, for example 60°C or 80°C; (6) Step S3 also includes post-treatment steps of standing and stratifying and removing the solvent in the organic phase.

8. The method for preparing high-purity 24-dehydrocholesterol according to any one of claims 1 to 4, characterized in that: Step S4 satisfies one or more of the following conditions: (1) The organic solvent is selected from one or both of ketone solvents and alcohol solvents, for example, a ketone solvent or an alcohol solvent; (2) The mass volume ratio of the crude product 1 to the organic solvent is 1 g: (4-60) ml, for example, 1 g: 10 ml, 1 g: 21 ml, 1 g: 31 ml, 1 g: 41 ml or 1 g: 51 ml; (3) The dissolving temperature is 50°C, 64°C, 75°C or 80°C; (4) The crystallization temperature is 20-25°C, for example 20°C; (5) The cooling rate is 10-25℃ / h; (6) After the crystallization is completed, the method further includes post-processing steps of filtering and removing the solvent.

9. The method for preparing high-purity 24-dehydrocholesterol according to claim 8, characterized in that: Step S4 satisfies one or more of the following conditions: (1) The ketone solvent is acetone; (2) The alcohol solvent is one or more of methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, ethylene glycol and glycerol, for example, one or more of methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol and ethylene glycol; for example, methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol or ethylene glycol.

10. The method for preparing high-purity 24-dehydrocholesterol according to any one of claims 1 to 4, characterized in that: The operation and conditions of step S5 are the same as those of step S4 described in claim 8 or 9.

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