Synthesis method of daidzein

Abstract

The invention relates to a method for synthesizing daidzein, and aims to provide a method for synthesizing daidzein with low environmental pollution, high catalytic activity, high yield and easy product separation. The technical scheme is as follows: (1) using trifluoromethanesulfonic acid as a catalyst, resorcinol and 4-hydroxyphenylacetic acid as raw materials to carry out condensation reaction to prepare 1-(2,4-dihydroxyphenyl)-2-(4-hydroxyphenyl)-ethanone, the condensation reaction temperature is 60-120 DEG C, and the reaction time is 1.5-8h; (2) using 1-(2,4-dihydroxyphenyl)-2-(4-hydroxyphenyl)-ethanone as a raw material, adding trimethyl orthoformate, using trifluoromethanesulfonic acid as a catalyst to carry out cyclization reaction, the reaction temperature is 0-35 DEG C, the reaction time is 2-10h, and then refining to obtain a daidzein finished product; the invention belongs to the field of synthesis technology.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical synthesis, and in particular relates to a method for synthesizing daidzein by catalyzing trifluoromethanesulfonic acid. Background Art

[0002] Daidzein is one of the isoflavone compounds contained in soybean seeds. It is also found in leguminous plants such as kudzu vine and alfalfa. Therefore, soybeans, kudzu vine, alfalfa and their processed foods, soy products, and kudzu powder products are regarded as foods with rich nutritional value and livestock feed. Daidzein has great application value in the fields of medicine and health food, but its content in soybeans is very low, only 2-3 mg / g, and it is difficult to form large-scale production by physical extraction methods. At present, daidzein is not only used as a cardiovascular and cerebrovascular drug, but also as a phytoestrogen in medicines and feed additives, which can treat women's menopausal syndrome and osteoporosis; daidzein can also be used in cancer prevention and anti-cancer and has certain positive effects. In addition, it can also be used in soybean planting to induce the production of soybean rhizobia and prevent and treat soybean root disease.

[0003] In the prior art, the industrial synthesis of daidzein is basically achieved by using resorcinol and 4-hydroxyphenylacetic acid as the main raw materials, synthesizing the intermediate 1-(2,4-dihydroxyphenyl)-2-(4-hydroxyphenyl)-ethanone through a condensation reaction, and then synthesizing daidzein through a cyclization reaction of the intermediate. In the condensation reaction, the current mainstream synthesis method uses boron trifluoride ether as a catalyst, and the yield can reach more than 70%, but there are disadvantages such as large catalyst dosage and difficulty in recycling the catalyst. In the cyclization reaction, the current mainstream synthesis method is to generate daidzein in the presence of a solvent DMF with an intermediate and methylsulfonyl chloride or phosphorus oxychloride, and the yield can reach more than 95%, but there are disadvantages such as the experimental process is difficult to control, the raw material purity requirement is high, and the product is difficult to separate. In order to reduce production costs and improve economic benefits, it is considered to use the same catalyst for the two-step synthesis to improve the catalytic efficiency of the catalyst, while also improving the yield of the reaction and causing less pollution to the environment.

[0004] In view of the above problems, trifluoromethanesulfonic acid is selected as a catalyst, which can significantly improve the catalytic activity and the utilization efficiency of the catalyst. In addition, trifluoromethanesulfonic acid is low in toxicity, stable in nature, and has little environmental pollution. In addition, the prepared solid-supported trifluoromethanesulfonic acid can be recovered and recycled, which is conducive to reducing production costs. Summary of the invention

[0005] To solve the above technical problems, the purpose of the present invention is to provide a method for synthesizing daidzein using trifluoromethanesulfonic acid as a catalyst, which has low environmental pollution, high catalytic activity, high yield and easy product separation.

[0006] To this end, the technical solution provided by the present invention is as follows:

[0007] (1) Using trifluoromethanesulfonic acid as a catalyst, resorcinol and 4-hydroxyphenylacetic acid as raw materials, a condensation reaction is carried out for 1.5-8 hours to prepare 1-(2,4-dihydroxyphenyl)-2-(4-hydroxyphenyl)-ethanone, and the condensation reaction temperature is 60-120° C. The reaction yield is above 90%, and the product purity is above 97%.

[0008] (2) Using 1-(2,4-dihydroxyphenyl)-2-(4-hydroxyphenyl)-ethanone as a raw material, adding trimethyl orthoformate, and carrying out a cyclization reaction catalyzed by trifluoromethanesulfonic acid, the reaction temperature is 0-35° C., the reaction time is 2-10 hours, and then the daidzein product is obtained by purification; the reaction yield is above 98%, and the product purity is above 97%.

[0009] The synthetic route of the present invention is:

[0010]

[0011] Furthermore, the molar ratio of resorcinol, 4-hydroxyphenylacetic acid and trifluoromethanesulfonic acid in step (1) is 1:1-1.5:1-2.5.

[0012] The molar ratio of 1-(2,4-dihydroxyphenyl)-2-(4-hydroxyphenyl)-ethanone, trimethyl orthoformate and trifluoromethanesulfonic acid in step (2) is 1:5-10:1-1.5.

[0013] Furthermore, the trifluoromethanesulfonic acid in step (1) and step (2) is liquid trifluoromethanesulfonic acid or immobilized trifluoromethanesulfonic acid formed by immobilizing trifluoromethanesulfonic acid on molecular sieves, metal oxides, clays, resins, etc.

[0014] Furthermore, the reaction temperature of step (1) is 60-120°C, preferably 70-110°C; the reaction time is 1.5-8h, preferably 1.5-3h.

[0015] Furthermore, the reaction temperature of step (2) is 0-35°C, preferably 10-25°C; the reaction time is 2-10h, preferably 4-8h.

[0016] Furthermore, the step (2) is carried out under nitrogen protection.

[0017] Compared with the prior art, the technical solution provided by the present invention has the following technical advantages:

[0018] 1. The technical solution provided by the present invention uses trifluoromethanesulfonic acid as a catalyst, and only one catalyst is needed to directly complete the two-step reaction, and the selectivity of the two-step reaction is as high as more than 97%.

[0019] 2. The technical solution of the present invention does not require a reaction solvent, has little environmental pollution and low production cost.

[0020] 3. The technical solution of the present invention adopts solid trifluoromethanesulfonic acid which can be recovered for recycling, and the amount of reaction catalyst used is small, which improves the utilization rate of the catalyst while maintaining high yield and high purity, and has the prospect of large-scale industrialization. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is the mass spectrum of 1-(2,4-dihydroxyphenyl)-2-(4-hydroxyphenyl)-ethanone of Example 2;

[0022] Figure 2 This is the mass spectrum of daidzein of Example 2.

[0023] Figure 3 It is the infrared spectra of the MCM-41 molecular sieve of Example 6 and trifluoromethanesulfonic acid supported by the MCM-41 molecular sieve. DETAILED DESCRIPTION

[0024] The present invention is further illustrated by way of examples below, but they do not constitute any limitation to the present invention. Any limited number of modifications made by anyone within the scope of the claims of the present invention are still within the scope of the claims of the present invention.

[0025] Example 1

[0026] (1) Preparation of 1-(2,4-dihydroxyphenyl)-2-(4-hydroxyphenyl)-ethanone by condensation reaction: 1.10 g (10 mmol) of resorcinol, 1.52 g (10 mmol) of 4-hydroxyphenylacetic acid, and 1 mmol of liquid trifluoromethanesulfonic acid were weighed and added into a three-necked flask, and heated to 110° C. for reaction for 2 h. After the reaction was completed, samples were collected and analyzed by high performance liquid chromatography (HPLC). The external standard method was used for quantitative analysis. The reaction conversion rate was 51.1%, and the reaction selectivity was 97.9%.

[0027] (2) Preparation of soybean aglycone by cyclization reaction of 1-(2,4-dihydroxyphenyl)-2-(4-hydroxyphenyl)-ethanone: Weigh 0.4884 g (2 mmol) of 1-(2,4-dihydroxyphenyl)-2-(4-hydroxyphenyl)-ethanone, add 1.10 mL (10 mmol) of trimethyl orthoformate and 88 μL (1 mmol) of liquid trifluoromethanesulfonic acid, and carry out cyclization reaction under N2 protection at a reaction temperature of 25°C for 4 hours. After the reaction is completed, samples are collected and analyzed by high performance liquid chromatography (HPLC). The external standard method is used for quantification. The reaction conversion rate is 49.3% and the reaction selectivity is 98.3%.

[0028] Example 2

[0029] (1) Preparation of 1-(2,4-dihydroxyphenyl)-2-(4-hydroxyphenyl)-ethanone by condensation reaction: 1.10 g (10 mmol) of resorcinol, 1.52 g (10 mmol) of 4-hydroxyphenylacetic acid, and 0.884 mL (10 mmol) of liquid trifluoromethanesulfonic acid were weighed and added to a three-necked flask, heated to 120°C for reaction for 0.5 h, and after the reaction, samples were taken for analysis by high performance liquid chromatography (HPLC). The external standard method was used for quantitative analysis, and the reaction conversion rate was 86.2%, and the reaction selectivity was 97.4%. 20 mL of deionized water was added to the remaining product in the flask to quench, and the product was filtered using a 0.22 μm organic filter membrane. The solid obtained by filtration was dried at 100°C for 24 h to obtain the intermediate 1-(2,4-dihydroxyphenyl)-2-(4-hydroxyphenyl)-ethanone. The sample was taken for liquid phase analysis, and the purity was 97.0%. The sample was taken for mass spectrometry analysis, and the attached Figure 1 .

[0030] (2) Preparation of daidzein by cyclization reaction of 1-(2,4-dihydroxyphenyl)-2-(4-hydroxyphenyl)-ethanone: Weigh 0.4884g (2mmol) of 1-(2,4-dihydroxyphenyl)-2-(4-hydroxyphenyl)-ethanone, add 1.10mL (10mmol) of trimethyl orthoformate and 177μL (2mmol) of liquid trifluoromethanesulfonic acid, and carry out cyclization reaction under N2 protection. The reaction temperature is 0℃ and the reaction time is 8h. After the reaction is completed, sample is taken for high performance liquid chromatography (HPLC) analysis. The external standard method is used for quantitative analysis. The reaction conversion rate is 95.5% and the reaction selectivity is 99.7%. Add 10mL of deionized water to the remaining product in the flask to quench, and filter with a 0.22μm organic filter membrane. The solid obtained by filtration is dried at 100℃ for 24h to obtain daidzein. Sample is taken for liquid phase analysis. The purity is 95.7%. Sample is taken for mass spectrometry analysis. Figure 2 .

[0031] Example 3

[0032] (1) Preparation of 1-(2,4-dihydroxyphenyl)-2-(4-hydroxyphenyl)-ethanone by condensation reaction: 1.10 g (10 mmol) of resorcinol, 1.52 g (10 mmol) of 4-hydroxyphenylacetic acid, and 2 mL (22.6 mmol) of liquid trifluoromethanesulfonic acid were weighed and added into a three-necked flask, and heated to 70° C. for reaction for 4 h. After the reaction was completed, samples were collected and analyzed by high performance liquid chromatography (HPLC). The external standard method was used for quantitative analysis. The reaction conversion rate was 92.5%, and the reaction selectivity was 97.2%.

[0033] (2) Preparation of soybean aglycone by cyclization reaction of 1-(2,4-dihydroxyphenyl)-2-(4-hydroxyphenyl)-ethanone: Weigh 0.4884 g (2 mmol) of 1-(2,4-dihydroxyphenyl)-2-(4-hydroxyphenyl)-ethanone, add 2 mL (18 mmol) of trimethyl orthoformate and 177 μL (2 mmol) of liquid trifluoromethanesulfonic acid, and carry out cyclization reaction under N2 protection at a reaction temperature of 25°C for 4 hours. After the reaction is completed, samples are collected and analyzed by high performance liquid chromatography (HPLC). The external standard method is used for quantification. The reaction conversion rate is 99.1% and the reaction selectivity is 98.3%.

[0034] Example 4

[0035] (1) Preparation of 1-(2,4-dihydroxyphenyl)-2-(4-hydroxyphenyl)-ethanone by condensation reaction: 1.10 g (10 mmol) of resorcinol, 2.28 g (15 mmol) of 4-hydroxyphenylacetic acid, and 2.20 mL (25 mmol) of liquid trifluoromethanesulfonic acid were weighed and added into a three-necked flask, and the mixture was heated to 60° C. and reacted for 5.5 h. After the reaction was completed, a sample was taken and analyzed by high performance liquid chromatography (HPLC). The external standard method was used for quantitative analysis. The reaction conversion rate was 94.7%, and the reaction selectivity was 98.6%.

[0036] (2) Preparation of soybean aglycone by cyclization reaction of 1-(2,4-dihydroxyphenyl)-2-(4-hydroxyphenyl)-ethanone: Weigh 0.4884 g (2 mmol) of 1-(2,4-dihydroxyphenyl)-2-(4-hydroxyphenyl)-ethanone, add 2.20 mL (20 mmol) of trimethyl orthoformate and 265 μL (3 mmol) of liquid trifluoromethanesulfonic acid, and carry out cyclization reaction under N2 protection at a reaction temperature of 35°C for 2 h. After the reaction is completed, samples are collected and analyzed by high performance liquid chromatography (HPLC). The external standard method is used for quantification. The reaction conversion rate is 99.1% and the reaction selectivity is 97.2%.

[0037] Example 5

[0038] (1) Preparation of 1-(2,4-dihydroxyphenyl)-2-(4-hydroxyphenyl)-ethanone by condensation reaction: 1.10 g (10 mmol) of resorcinol, 1.9 g (12.5 mmol) of 4-hydroxyphenylacetic acid, and 1.5 mL (17 mmol) of liquid trifluoromethanesulfonic acid were weighed and added into a three-necked flask, and the mixture was heated to 80° C. for reaction for 3 h. After the reaction was completed, a sample was taken and analyzed by high performance liquid chromatography (HPLC). The external standard method was used for quantitative analysis. The reaction conversion rate was 93.0%, and the reaction selectivity was 97.9%.

[0039] (2) Preparation of soybean aglycone by cyclization reaction of 1-(2,4-dihydroxyphenyl)-2-(4-hydroxyphenyl)-ethanone: Weigh 0.4884 g (2 mmol) of 1-(2,4-dihydroxyphenyl)-2-(4-hydroxyphenyl)-ethanone prepared in the above step, add 1.75 mL (16 mmol) of trimethyl orthoformate and 220 μL (2.5 mmol) of liquid trifluoromethanesulfonic acid, and carry out cyclization reaction under N2 protection at a reaction temperature of 25°C for 4 hours. After the reaction is completed, samples are collected and analyzed by high performance liquid chromatography (HPLC). The external standard method is used for quantification. The reaction conversion rate is 98.5%, and the reaction selectivity is 99.3%.

[0040] Example 6

[0041] (1) Preparation of trifluoromethanesulfonic acid supported on MCM-41 molecular sieve: weigh 2g of MCM-41 molecular sieve into a flask, add 15mL of toluene, then drop 1.5g (10mmol) of liquid trifluoromethanesulfonic acid, stir at 90°C for 1h under N2 protection, and after stirring, use reduced pressure rotary distillation at 60°C and vacuum degree -1.0MPa to remove most of the toluene, place in a vacuum drying oven at 60°C and stand for 24h to remove all solvents, and obtain trifluoromethanesulfonic acid supported on MCM-41 molecular sieve. Its infrared spectrum is shown in the attached figure. Figure 3 , by the attached Figure 3 It can be seen that trifluoromethanesulfonic acid has been successfully loaded on the MCM-41 molecular sieve.

[0042] (2) Preparation of 1-(2,4-dihydroxyphenyl)-2-(4-hydroxyphenyl)-ethanone by condensation reaction: 1.10 g (0.01 mol) of resorcinol, 1.52 g (0.01 mol) of 4-hydroxyphenylacetic acid, and 0.35 g of trifluoromethanesulfonic acid supported by MCM-41 molecular sieve were weighed and added to a three-necked flask, heated to 110°C until the raw materials melted, and reacted for 2 h. After the reaction, samples were taken for analysis by high performance liquid chromatography (HPLC). The external standard method was used for quantitative analysis. The reaction conversion rate was 40.5% and the reaction selectivity was 97.0%. 20 mL of methanol was added to the reaction product for dilution, and the diluted reaction product was filtered using a 0.22 μm organic filter membrane. The obtained solid was dried in a vacuum drying oven at 60°C for 24 h, and the catalyst was recovered and reused.

[0043] (3) Preparation of soybean aglycone by cyclization reaction of 1-(2,4-dihydroxyphenyl)-2-(4-hydroxyphenyl)-ethanone: Weigh 0.4882 g (2 mmol) of 1-(2,4-dihydroxyphenyl)-2-(4-hydroxyphenyl)-ethanone prepared in the above step, add 2 ml of trimethyl orthoformate and 0.35 g of trifluoromethanesulfonic acid supported by MCM-41 molecular sieve, and carry out cyclization reaction under N2 protection, the reaction temperature is 25°C, the reaction time is 4 hours, and after the reaction is completed, a sample is taken for analysis by high performance liquid chromatography (HPLC), and the quantitative analysis is performed by external standard method. The reaction conversion rate is 36.4%, and the reaction selectivity is 97.9%. The reaction product is filtered by using a 0.22 μm organic filter membrane, and the obtained solid is dried in a vacuum drying oven at 60°C for 24 hours, and the catalyst is recovered and reused.

[0044] Example 7

[0045] (1) Preparation of trifluoromethanesulfonic acid supported on DA330 resin: 2 g of DA330 resin was weighed into a flask, 30 mL of ether was added, and then 3 g (20 mmol) of liquid trifluoromethanesulfonic acid was added dropwise. The mixture was stirred at 30° C. for 3 h under N2 protection. Most of the ether was removed by reduced pressure distillation at 25° C. and a vacuum degree of -1.0 MPa. The mixture was placed in a vacuum drying oven at 60° C. for 24 h to remove all the ether, thereby obtaining trifluoromethanesulfonic acid supported on DA330 resin.

[0046] (2) Preparation of 1-(2,4-dihydroxyphenyl)-2-(4-hydroxyphenyl)-ethanone by condensation reaction: 1.10 g (0.01 mol) of resorcinol, 1.52 g (0.01 mol) of 4-hydroxyphenylacetic acid, and 0.25 g of trifluoromethanesulfonic acid supported by DA330 resin were weighed and added to a three-necked flask, heated to 110°C until the raw materials melted, and reacted for 2 h. After the reaction, samples were taken for analysis by high performance liquid chromatography (HPLC). The external standard method was used for quantitative analysis. The reaction conversion rate was 45.8%, and the reaction selectivity was 97.3%. 20 mL of methanol was added to the reaction product for dilution, and the diluted reaction product was filtered using a 0.22 μm organic filter membrane. The obtained solid was dried in a vacuum drying oven at 60°C for 24 h, and the catalyst was recovered and reused.

[0047] (3) Preparation of daidzein by cyclization reaction of 1-(2,4-dihydroxyphenyl)-2-(4-hydroxyphenyl)-ethanone: Weigh 0.4882 g (2 mmol) of 1-(2,4-dihydroxyphenyl)-2-(4-hydroxyphenyl)-ethanone prepared in the above step, add 2 ml of trimethyl orthoformate and 0.25 g of trifluoromethanesulfonic acid supported by DA330 resin, and carry out cyclization reaction under N2 protection at a reaction temperature of 25°C for 4 hours. After the reaction, samples were taken for analysis by high performance liquid chromatography (HPLC). The quantitative analysis was performed by external standard method. The reaction conversion rate was 39.5% and the reaction selectivity was 98.1%. The reaction product was filtered by a 0.22 μm organic filter membrane, and the obtained solid was dried in a vacuum drying oven at 60°C for 24 hours. The catalyst was recovered and reused.

[0048] Example 8

[0049] (1) Preparation of trifluoromethanesulfonic acid supported on silica (SiO2): 2 g of silica was weighed into a flask, 20 mL of trichlorotrifluoroethane was added, and then 2 g (11.8 mmol) of liquid trifluoromethanesulfonic acid was added dropwise, and the mixture was stirred at 50°C for 2 h. Most of the trichlorotrifluoroethane was removed by reduced pressure rotary distillation at 60°C and a vacuum degree of -1.0 MPa. The mixture was placed in a vacuum drying oven at 60°C and allowed to stand for 24 h to remove all the trichlorotrifluoroethane, thereby obtaining trifluoromethanesulfonic acid supported on silica.

[0050] (2) Preparation of 1-(2,4-dihydroxyphenyl)-2-(4-hydroxyphenyl)-ethanone by condensation reaction: 1.10 g (0.01 mol) of resorcinol, 1.52 g (0.01 mol) of 4-hydroxyphenylacetic acid, and 0.34 g of trifluoromethanesulfonic acid supported by silica were weighed and added to a three-necked flask, heated to 110°C until the raw materials melted, and reacted for 2 h. After the reaction, samples were taken for analysis by high performance liquid chromatography (HPLC). The external standard method was used for quantitative analysis. The reaction conversion rate was 38.4% and the reaction selectivity was 97.1%. 20 mL of methanol was added to the reaction product for dilution, and the diluted reaction product was filtered using a 0.22 μm organic filter membrane. The obtained solid was dried in a vacuum drying oven at 60°C for 24 h, and the catalyst was recovered and reused.

[0051] (3) Preparation of soybean aglycone by cyclization reaction of 1-(2,4-dihydroxyphenyl)-2-(4-hydroxyphenyl)-ethanone: Weigh 0.4882 g (2 mmol) of 1-(2,4-dihydroxyphenyl)-2-(4-hydroxyphenyl)-ethanone prepared in the above step, add 2 ml of trimethyl orthoformate and 0.34 g of trifluoromethanesulfonic acid supported by silica, and carry out cyclization reaction under N2 protection at a reaction temperature of 25°C for 4 hours. After the reaction is completed, samples are taken for analysis by high performance liquid chromatography (HPLC). The quantitative analysis is performed by external standard method. The reaction conversion rate is 31.4% and the reaction selectivity is 97.3%. The reaction product is filtered by a 0.22 μm organic filter membrane, and the obtained solid is dried in a vacuum drying oven at 60°C for 24 hours. The catalyst is recovered and reused.

[0052] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

[0053] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for synthesizing daidzein, characterized in that: The steps are as follows: (1) Using trifluoromethanesulfonic acid as a catalyst, resorcinol and 4-hydroxyphenylacetic acid as raw materials, the reaction temperature is 60-120°C, and the reaction time is 1.5-8h to synthesize 1-(2,4-dihydroxyphenyl)-2-(4-hydroxyphenyl)-ethanone by condensation reaction; The molar ratio of resorcinol, 4-hydroxyphenylacetic acid and trifluoromethanesulfonic acid is 1:1-1.5:1-2.5; (2) Using 1-(2,4-dihydroxyphenyl)-2-(4-hydroxyphenyl)-ethanone as a raw material, adding trimethyl orthoformate and trifluoromethanesulfonic acid as a catalyst, reacting at 0-35°C for 2-10 hours under the protection of an inert gas, performing a ring-closing reaction, and then performing post-treatment and purification to obtain a finished product of daidzein; The molar ratio of 1-(2,4-dihydroxyphenyl)-2-(4-hydroxyphenyl)-ethanone, trimethyl orthoformate and trifluoromethanesulfonic acid is 1:5-10:1-1.5; The trifluoromethanesulfonic acid in step (1) is liquid trifluoromethanesulfonic acid or solid trifluoromethanesulfonic acid.

2. The method for synthesizing daidzein according to claim 1, characterized in that: The immobilized trifluoromethanesulfonic acid is formed by immobilizing trifluoromethanesulfonic acid on molecular sieve, or on metal oxide, or on clay, or on resin.

3. The method for synthesizing daidzein according to claim 1, characterized in that: The reaction temperature in step (1) is 70-110° C. and the reaction time is 1.5-3 h.

4. The method for synthesizing daidzein according to claim 1, characterized in that: The reaction temperature in step (2) is 10-25°C and the reaction time is 4-8h.

5. The method for synthesizing daidzein according to claim 1, characterized in that: The inert gas in step (2) is nitrogen.

6. The method for synthesizing daidzein according to claim 1 or 2, characterized in that: The preparation steps of the immobilized trifluoromethanesulfonic acid are as follows: Weigh the solid carrier and add it to the flask, then add the solvent, then dropwise add trifluoromethanesulfonic acid, stir at room temperature for 0.5-3h, remove most of the solvent by rotary evaporation, place in a vacuum drying oven at 60°C for 24h to remove all the solvent, and thus obtain a solid-supported trifluoromethanesulfonic acid catalyst; The ratio of the solid carrier, the solvent and trifluoromethanesulfonic acid is 1g:15-30ml:0.75-2.5g.

7. The method for synthesizing daidzein according to claim 6, characterized in that: The solid carrier is one of MCM-41 molecular sieve, mesoporous Y-type molecular sieve, NaY molecular sieve, ZSM-5 molecular sieve, Beta molecular sieve, 13X molecular sieve, TiO2, SiO2, clay or resin.

8. The method for synthesizing daidzein according to claim 6, characterized in that: The solvent is one or more of benzene, toluene, ethylbenzene, isopropylbenzene, trichlorotrifluoroethane, carbon tetrachloride, ether, dichloromethane, dichloroethane, tetrahydrofuran or acetone.

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