A method for preparing high-purity captocin

Abstract

This invention provides a method for preparing high-purity catoroxane. The method uses ethylferrocene and dimethoxypropane as reactants, which undergo a condensation reaction in a solvent under the action of an acid catalyst to obtain catoroxane. This invention uses readily available and more reactive 2,2-dimethoxypropane instead of acetone for the condensation reaction to prepare catoroxane. Because 2,2-dimethoxypropane itself has higher reactivity and produces two molecules of methanol after the reaction, the reaction exhibits a larger entropy change, which is more conducive to the forward reaction. Ultimately, the reaction can be carried out under milder conditions with higher conversion and yield of catoroxane. The reaction solution can be simply washed with water and concentrated to complete the product post-processing, without the need for complex impurity removal processes. The purity of the obtained catoroxane can reach over 95%, showing excellent industrialization prospects. In summary, this invention provides a simple and efficient production method for the large-scale preparation of high-purity catoroxane.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of organic synthesis and relates to the synthesis of catocene, in particular to a preparation method of high-purity catocene. BACKGROUND

[0002] Catocene is an important binuclear ferrocene derivative, and due to its excellent catalytic activity and pharmaceutical process, it has become one of the main burning rate catalysts in current composite solid propellants. Foreign countries started early research on catocene, mainly focusing on the improvement of the synthesis method, the optimization of the burning rate catalytic performance and the application in solid propellants. The structural formula of catocene is as follows:

[0003]

[0004] The synthesis process of catocene is complex, and the product contains various impurities and isomers, which will affect the performance and application of catocene, so the synthesis research of catocene has important theoretical significance and practical application value.

[0005] At present, the preparation of catocene at home and abroad is mainly through the condensation reaction of ethyl ferrocene and acetone under acidic conditions, and the synthesis route is as follows:

[0006]

[0007] The synthesis route has the problems of incomplete conversion of ethyl ferrocene raw materials due to the poor reactivity of acetone, about 8% of the raw materials remaining in the system, and part of the monosubstituted ferrocene impurities in the reaction. The unreacted ethyl ferrocene and mononuclear ferrocene impurities are small in molecular weight and easy to migrate, which will cause uneven combustion of the propellant and affect the mechanical and ballistic properties of the propellant, so it is necessary to remove them in the post-processing. Since the boiling point of ethyl ferrocene and its impurities is as high as 200℃ or above and catocene will undergo oxidation, polymerization and other side reactions in the long-term heating process, the unreacted ethyl ferrocene impurities are usually removed by high-vacuum reduced pressure distillation, water vapor distillation or solvent beating, which causes the problems of complex production process of catocene, low product purity and high comprehensive cost. SUMMARY

[0008] In view of the defects and deficiencies of the prior art, the purpose of the present application is to provide a preparation method of high-purity catocene, which solves the technical problems of complex impurity treatment process, low product purity and high comprehensive cost in the synthesis of catocene by using acetone as raw material in the prior art.

[0009] In order to solve the above technical problems, the technical scheme is adopted as follows:

[0010] A method for preparing high-purity cattocin, comprising: using ethyl ferrocene and dimethoxypropane as reactants, carrying out a condensation reaction in a solvent under the action of an acid catalyst to obtain cattocin.

[0011] The acid catalyst is selected from trifluoroacetic acid or 98 wt.% concentrated sulfuric acid; trifluoroacetic acid is preferred.

[0012] The solvent is selected from one or more of dichloromethane, hexafluoroisopropanol, trifluoroethanol, ethyl acetate, 1,2-dichloroethane, methanol, and ethanol. Dichloromethane, hexafluoroisopropanol, or trifluoroethanol are preferred.

[0013] The present invention also has the following technical features:

[0014] Specifically, the condensation reaction is carried out at a temperature of 20–100°C for 2–8 hours.

[0015] Preferably, the condensation reaction is carried out at a temperature of 25–60°C for 3–6.5 h.

[0016] Specifically, the molar ratio of ethyl ferrocene to dimethoxypropane is (0.05-0.5):0.05.

[0017] Specifically, the molar ratio of the ethyl ferrocene to the acid catalyst is (0.05-0.5):(0.001-0.01).

[0018] Specifically, the mass ratio of the ethyl ferrocene to the solvent is (21.4-23):(60-80).

[0019] Preferably, the molar ratio of ethyl ferrocene, dimethoxypropane and acid catalyst is 0.1:0.05:(0.0027~0.0052).

[0020] Preferably, the mass ratio of ethyl ferrocene, dimethoxypropane, acid catalyst and solvent is 21.4:5.2:(0.31~0.6):60.

[0021] Specifically, thin-layer chromatography was used to detect the progress of the condensation reaction, with 100% n-hexane as the developing solvent.

[0022] Specifically, the method also includes: after the condensation reaction is completed, quenching is performed by adding 10% sodium bicarbonate aqueous solution, then the aqueous phase is separated, the organic phase is extracted twice with dichloromethane, the organic phases are combined, the organic phase is dried with anhydrous sodium sulfate, filtered and concentrated to obtain purified captosine.

[0023] The beneficial technical effects of this invention compared to the prior art are as follows:

[0024] This invention utilizes 2,2-dimethoxypropane, which is economical, readily available, and more reactive, to replace acetone in the condensation process to prepare captocin. Because 2,2-dimethoxypropane itself has higher reactivity and produces two molecules of methanol after the reaction, the reaction exhibits a larger entropy change, which is more conducive to the forward reaction. Ultimately, this allows the reaction to produce captocin under milder conditions with higher conversion and yield. The reaction solution can be simply washed with water and concentrated for post-processing, eliminating the need for complex impurity removal processes. The obtained captocin achieves a purity of over 95%, demonstrating excellent industrialization potential. In summary, this invention provides a simple and efficient production method for the large-scale preparation of high-purity captocin. Attached Figure Description

[0025] Figure 1 This is the hydrogen NMR spectrum of Katoxine.

[0026] The specific content of the present invention will be further explained in detail below with reference to the embodiments. Detailed Implementation

[0027] It should be noted that, unless otherwise specified, all raw materials used in this invention are those known in the art.

[0028] The synthetic route of this invention is as follows:

[0029]

[0030] Following the above technical solutions, specific embodiments of the present invention are given below. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent modifications made based on the technical solutions of this application fall within the protection scope of the present invention.

[0031] Example 1:

[0032] This embodiment provides a method for preparing high-purity captosine, which specifically includes the following steps: 21.4 g (0.1 mol) of ethyl ferrocene, 5.2 g (0.05 mol) of dimethoxypropane, and 0.31 g (0.0027 mol) of trifluoroacetic acid are added sequentially to 60 g of dichloromethane solvent. The reaction is stirred at 25°C for 6.5 hours. After the reaction is detected by thin-layer chromatography (developing solvent: 100% n-hexane), 20 mL of 10% sodium bicarbonate aqueous solution is added to quench the reaction. The aqueous phase is then separated and extracted twice with 50 mL of dichloromethane. The organic phases are combined, dried over anhydrous sodium sulfate, filtered, and concentrated to obtain 20 g of product.

[0033] In this embodiment, gas chromatography was used to analyze the product. The gas chromatography analysis conditions were as follows: column type: DB-1, 0.25μm*30m; detector temperature FID: 310℃; injection port temperature: 310℃; column temperature program: initial 120℃, increase to 220℃ at 35℃ / min, then increase to 300℃ at 10℃ / min, and hold for 7min.

[0034] In this embodiment, the product is identified, and the identification results are as follows: Figure 1 As shown, the 1H NMR data are as follows: 1H NMR (500MHz, CDCl3) δ 4.37–3.78 (m, 16H), 2.61–2.20 (m, 4H), 1.82–1.52 (m, 6H), 1.27–1.04 (s, 6H). From the above results, it can be seen that the target product, cattocin, was successfully synthesized in this embodiment; the yield of cattocin was 86%, and the gas chromatography normalized content was 96%.

[0035] Example 2:

[0036] This embodiment provides a method for preparing high-purity captocin, which specifically includes the following steps: 21.4 g (0.1 mol) of ethyl ferrocene, 5.2 g (0.05 mol) of dimethoxypropane, and 0.31 g (0.0027 mol) of trifluoroacetic acid are added sequentially to 60 g of hexafluoroisopropanol solvent. The reaction is stirred at 25°C for 6.5 hours. After the reaction is detected by thin-layer chromatography (developing solvent: 100% n-hexane), 20 mL of 10% sodium bicarbonate aqueous solution is added to quench the reaction. The aqueous phase is then separated, and the organic phase is extracted twice with 50 mL of dichloromethane. The organic phases are combined, dried over anhydrous sodium sulfate, filtered, and concentrated to obtain 22.3 g of captocin.

[0037] In this embodiment, the yield of captocin was 95%, and the normalized content by gas chromatography was 97%.

[0038] Example 3:

[0039] This embodiment provides a method for preparing high-purity captocin, which specifically includes the following steps: 21.4 g (0.1 mol) of ethyl ferrocene, 5.2 g (0.05 mol) of dimethoxypropane, and 0.6 g (0.0052 mol) of trifluoroacetic acid are added sequentially to 60 g of trifluoroethanol solvent. The reaction is stirred at 50 °C for 3 hours. After the reaction is detected by thin-layer chromatography (developing solvent: 100% n-hexane), 20 mL of 10% sodium bicarbonate aqueous solution is added to quench the reaction. The aqueous phase is then separated, and the organic phase is extracted twice with 50 mL of dichloromethane. The organic phases are combined, dried over anhydrous sodium sulfate, filtered, and concentrated to obtain 21.5 g of captocin.

[0040] In this embodiment, the yield of captocin was 92%, and the normalized content by gas chromatography was 95%.

[0041] Comparative Example 1:

[0042] This comparative example provides a method for preparing high-purity captosine, which is basically the same as the example method, with the main differences being the solvent and acid catalyst. The method specifically includes the following steps: 23 g (0.11 mol) ethyl ferrocene, 5.2 g (0.05 mol) dimethoxypropane, and 0.25 g (0.0025 mol) 98 wt.% concentrated sulfuric acid are added sequentially to 80 g of ethyl acetate solvent. The reaction is stirred at 60°C for 3 hours. After the reaction is detected by thin-layer chromatography (developing solvent: 100% n-hexane), 20 mL of 10% sodium bicarbonate aqueous solution is added to quench the reaction. The aqueous phase is then separated, and the organic phase is extracted twice with 50 mL of dichloromethane. The organic phases are combined, dried over anhydrous sodium sulfate, filtered, and concentrated to obtain 18.3 g of captosine.

[0043] In this comparative example, the yield of captocin was 78%, and the gas chromatography normalized content was 95%. Compared with Examples 1 to 3, the yield of captocin decreased.

Claims

1. A method for preparing high-purity captocin, characterized in that, The method includes: using ethyl ferrocene and dimethoxypropane as reactants, carrying out a condensation reaction in a solvent under the action of an acid catalyst to prepare captocin; The acid catalyst is selected from trifluoroacetic acid or 98 wt.% concentrated sulfuric acid; The solvent is selected from dichloromethane, hexafluoroisopropanol, or trifluoroethanol.

2. The method for preparing high-purity captocin as described in claim 1, characterized in that, The condensation reaction is carried out at a temperature of 20–100°C for 2–8 hours.

3. The method for preparing high-purity captocin as described in claim 2, characterized in that, The condensation reaction is carried out at a temperature of 25–60°C for 3–6.5 h.

4. The method for preparing high-purity captocin as described in claim 1, characterized in that, The molar ratio of ethyl ferrocene to dimethoxypropane is (0.05-0.5):0.

05.

5. The method for preparing high-purity captocin as described in claim 1, characterized in that, The molar ratio of the ethyl ferrocene to the acid catalyst is (0.05-0.5):(0.001-0.01).

6. The method for preparing high-purity captocin as described in claim 1, characterized in that, The mass ratio of the ethyl ferrocene to the solvent is (21.4-23):(60-80).

7. The method for preparing high-purity captocin as described in claim 1, characterized in that, The molar ratio of ethyl ferrocene, dimethoxypropane and acid catalyst is 0.1:0.05:(0.0027~0.0052).

8. The method for preparing high-purity captocin as described in claim 1, characterized in that, The mass ratio of ethyl ferrocene, dimethoxypropane, acid catalyst, and solvent is 21.4:5.2:(0.31-0.6):

60.

9. The method for preparing high-purity captocin as described in claim 1, characterized in that, Thin-layer chromatography was used to detect the progress of the condensation reaction, with 100% n-hexane as the developing solvent.

10. The method for preparing high-purity captocin as described in claim 1, characterized in that, The method also includes: after the condensation reaction is completed, quenching is performed by adding 10% sodium bicarbonate aqueous solution, then separating the aqueous phase, extracting the organic phase twice with dichloromethane, combining the organic phases, drying the organic phase with anhydrous sodium sulfate, filtering and concentrating to obtain purified captosine.

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