Preparation method of high-purity cartosin

Abstract

The invention provides a preparation method of high-purity cartosin, which comprises the following steps: taking ethyl ferrocene and dimethoxypropane as reaction raw materials, and carrying out condensation reaction in a solvent under the action of an acid catalyst to prepare the cartosin. According to the method, 2, 2-dimethoxypropane which is economical, easy to obtain and higher in reaction activity is adopted to replace acetone to be condensed to prepare the cartosine, due to the fact that 2, 2-dimethoxypropane has higher reaction activity, two-molecule methanol is generated after the reaction is finished, the reaction has larger entropy change, forward proceeding of the reaction is more facilitated, and the yield of the cartosine is increased. And finally, the cartosin can be prepared under milder conditions at a higher conversion rate and a higher yield. And the reaction liquid is simply washed and concentrated to finish post-treatment of the product, and a complicated process for impurity removal is not needed. The purity of the obtained cartosin can reach 95% or above, and the method has an excellent industrial prospect. In conclusion, the invention provides a simple and efficient production method for large-scale preparation of the high-purity cartosin.

Description

Technical Field

[0001] The invention belongs to the technical field of organic synthesis, relates to the synthesis of catoctenes, and particularly relates to a method for preparing high-purity catoctenes. Background Art

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

[0003]

[0004] The synthesis process of catoctenyl is complicated, and the product contains a variety of impurities and isomers, which will affect the performance and application of catoctenyl. Therefore, the synthesis research of catoctenyl has important theoretical significance and practical application value.

[0005] At present, the preparation of cartocin at home and abroad is mainly obtained by the condensation reaction of ethylferrocene and acetone under acidic conditions. The synthesis route is as follows:

[0006]

[0007] Due to the poor reactivity of acetone, the synthetic route results in incomplete conversion of the ethylferrocene raw material, and about 8% of the raw materials remain in the system. In addition, there are some monosubstituted ferrocene impurities in the reaction. The unreacted ethylferrocene and mononuclear ferrocene impurities have small molecular weights and are easy to migrate, which will cause uneven combustion of the propellant and affect the mechanical and ballistic properties of the propellant, so they need to be removed in post-processing. Since the boiling point of ethylferrocene and its impurities is as high as 200°C and catocene undergoes side reactions such as oxidation and polymerization during long-term heating, the unreacted ethylferrocene impurities separated by post-processing usually need to be removed by high vacuum reduced pressure distillation, steam distillation or solvent beating, which causes problems such as complex production process, low product purity and high overall cost of catocene. Summary of the invention

[0008] In view of the defects and shortcomings of the prior art, the object of the present invention is to provide a method for preparing high-purity catoctenes, so as to solve the technical problems in the prior art of synthesizing catoctenes using acetone as a raw material, such as complex impurity treatment process, low product purity and high comprehensive cost.

[0009] In order to solve the above technical problems, the present invention adopts the following technical solutions to achieve the above problems:

[0010] A method for preparing high-purity catoctenes comprises: using ethylferrocene and dimethoxypropane as reaction raw materials, carrying out a condensation reaction in a solvent under the action of an acid catalyst to prepare catoctenes.

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

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

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

[0014] Specifically, the reaction temperature of the condensation reaction is 20-100° C., and the reaction time is 2-8 hours.

[0015] Preferably, the reaction temperature of the condensation reaction is 25-60° C., and the reaction time is 3-6.5 h.

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

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

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

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

[0020] Preferably, the mass ratio of ethylferrocene, 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, and 100% normal hexane was used as a developing solvent during the thin layer chromatography detection.

[0022] Specifically, the method further comprises: after the condensation reaction is completed, adding 10% sodium bicarbonate aqueous solution to quench, then separating the aqueous phase, extracting the organic phase twice with dichloromethane, combining the organic phases, drying the organic phases with anhydrous sodium sulfate, filtering and concentrating, and obtaining purified catoctin.

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

[0024] The present invention adopts 2,2-dimethoxypropane, which is economically available and has higher reaction activity, to replace acetone for condensation to prepare catoctin. Since 2,2-dimethoxypropane itself has higher reaction activity and generates two molecules of methanol after the reaction, the reaction has a larger entropy change, which is more conducive to the forward reaction, and finally enables the reaction to be prepared under milder conditions with higher conversion rate and yield. The reaction solution can be simply washed with water and concentrated to complete the product post-processing, without the need to adopt a complex process for impurity removal. The purity of the obtained catoctin can reach more than 95%, and it has excellent industrial prospects. In summary, the present invention provides a simple and efficient production method for the large-scale preparation of high-purity catoctin. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0026] The specific contents of the present invention are further explained in detail below in conjunction with embodiments. DETAILED DESCRIPTION

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

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

[0029]

[0030] In accordance with the above technical scheme, 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 changes made on the basis of the technical scheme of this application fall within the protection scope of the present invention.

[0031] Embodiment 1:

[0032] This embodiment provides a method for preparing high-purity catocine, which specifically includes the following process: 21.4 grams (0.1 mol) of ethylferrocene, 5.2 grams (0.05 mol) of dimethoxypropane and 0.31 grams (0.0027 mol) of trifluoroacetic acid are added to 60 grams of dichloromethane solvent in sequence, and the reaction is stirred at 25°C for 6.5 hours. After the reaction is completed by thin layer chromatography (developing solvent: 100% n-hexane), 20 milliliters of 10% sodium bicarbonate aqueous solution are added to quench. Subsequently, the aqueous phase is separated, the aqueous phase is extracted twice with 50 milliliters of dichloromethane, the organic phase is combined, the organic phase is dried with anhydrous sodium sulfate, filtered and concentrated to obtain 20 grams of product.

[0033] In this embodiment, gas chromatography was used to analyze the product, and the gas chromatography analysis conditions were as follows: chromatographic column model: DB-1, 0.25μm*30m; detector temperature FID: 310°C; injection port temperature: 310°C; column temperature program: initial 120°C, 35°C / min to 220°C, then 10°C / min to 300°C, and keep warm for 7 minutes.

[0034] In this example, the product was identified. Figure 1 As shown, the H NMR spectrum data are as follows: 1H NMR (500 MHz, CDCl3) δ4.37–3.78 (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, catoctin, is finally synthesized in this embodiment; the yield of catoctin is 86%, and the gas chromatography normalized content is 96%.

[0035] Embodiment 2:

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

[0037] In this embodiment, the yield of catocten is 95%, and the gas chromatography normalized content is 97%.

[0038] Embodiment 3:

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

[0040] In this embodiment, the yield of catocten is 92%, and the gas chromatography normalized content is 95%.

[0041] Comparative Example 1:

[0042] This comparative example provides a method for preparing high-purity catoctenes, which is basically the same as the embodiment, and the main difference is that the solvent is different and the acid catalyst is different. The method specifically includes the following process: 23 grams (0.11 mol) of ethylferrocene, 5.2 grams (0.05 mol) of dimethoxypropane and 0.25 grams (0.0025 mol) of 98wt.% concentrated sulfuric acid are added to 80 grams of ethyl acetate solvent in sequence, and the reaction is stirred at 60°C for 3 hours. After the reaction is completed by thin layer chromatography (developing solvent: 100% n-hexane), 20 milliliters of 10% sodium bicarbonate aqueous solution are added to quench. Subsequently, the aqueous phase is separated, the organic phase is extracted twice with 50 milliliters of dichloromethane, the organic phase is combined, the organic phase is dried with anhydrous sodium sulfate, filtered and concentrated to obtain 18.3 grams of catoctenes.

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

Claims

1. A method for preparing high-purity catoctin, characterized in that: The method comprises: using ethylferrocene and dimethoxypropane as reaction raw materials, carrying out a condensation reaction in a solvent under the action of an acid catalyst to prepare catocine; The acid catalyst is selected from trifluoroacetic acid or 98wt.% concentrated sulfuric acid; The solvent is selected from one or more of dichloromethane, hexafluoroisopropanol, trifluoroethanol, ethyl acetate, 1,2-dichloroethane, methanol and ethanol.

2. The method for preparing high-purity catoctin according to claim 1, characterized in that: The reaction temperature of the condensation reaction is 20-100° C., and the reaction time is 2-8 hours.

3. The method for preparing high-purity catoctin as claimed in claim 2, characterized in that: The reaction temperature of the condensation reaction is 25-60° C., and the reaction time is 3-6.5 hours.

4. The method for preparing high-purity catoctin according to claim 1, characterized in that: The molar ratio of ethylferrocene to dimethoxypropane is (0.05-0.5):0.

05.

5. The method for preparing high-purity catoctin according to claim 1, characterized in that: The molar ratio of the ethylferrocene to the acid catalyst is (0.05-0.5): (0.001-0.01).

6. The method for preparing high-purity catoctin according to claim 1, characterized in that: The mass ratio of the ethylferrocene to the solvent is (21.4-23): (60-80).

7. The method for preparing high-purity catoctin according to claim 1, characterized in that: The molar ratio of the ethylferrocene, dimethoxypropane and acid catalyst is 0.1:0.05:(0.0027-0.0052).

8. The method for preparing high-purity catoctin according to claim 1, characterized in that: The mass ratio of the ethylferrocene, dimethoxypropane, acid catalyst and solvent is 21.4:5.2:(0.31-0.6):

60.

9. The method for preparing high-purity catoctin according to claim 1, characterized in that: The progress of the condensation reaction was detected by thin layer chromatography, and 100% n-hexane was used as a developing solvent.

10. The method for preparing high-purity catoctin according to claim 1, characterized in that: The method further comprises: after the condensation reaction is completed, adding a 10% sodium bicarbonate aqueous solution for quenching, then separating the aqueous phase, extracting the organic phase twice with dichloromethane, combining the organic phases, drying the organic phases with anhydrous sodium sulfate, filtering and concentrating, and obtaining purified catoctin.

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