A method for preparing dicyclopropane high-energy fuels from olefins using ionic liquid catalysis

Abstract

This invention discloses a method for preparing dicyclopropane high-energy fuel from olefins using ionic liquid catalysis. The specific process is as follows: olefins, ionic liquids, Zn powder, CH2I2, and organic solvents are mixed and reacted at a certain temperature for a period of time. After the reaction, the mixture is filtered and separated to obtain dicyclopropane high-energy fuel. This method is simple to operate, reacts rapidly, and yields high-purity dicyclopropane high-energy fuel. Compared to protonic acid catalysts, it has advantages such as catalyst stability and less environmental impact.

Description

Technical Field

[0001] This invention belongs to the field of high-energy fuel synthesis technology, specifically relating to a method for preparing dicyclopropane high-energy fuel by reacting olefins with CH2I2 using ionic liquid catalysis. Background Technology

[0002] The rapid development of the aerospace industry has placed higher demands on high-energy fuels, with increasing fuel density and calorific value becoming an important direction for their development. Hydrocarbon-based high-energy fuels have advantages such as being non-toxic and environmentally friendly. Introducing a three-membered ring (i.e., cyclopropane) into the hydrocarbon molecule structure, which possesses angular and torsional strain, can not only increase fuel density but also improve its calorific value, making it an effective method for preparing high-energy fuels.

[0003] The Simmons-Smith cyclopropanation reaction is characterized by mild conditions, good reproducibility, and wide applicability. Patent CN 101239881B discloses a method for preparing cyclopropane high-energy fuels from olefins using a zinc-copper atom catalyst. In this method, dicyclopentadiene is used as the substrate, CH2I2 as a carbene precursor, and I2 is added for ultrasonic reaction. However, elemental iodine easily sublimates and evaporates at room temperature, releasing iodine vapor, posing a significant risk, and the ultrasonic reaction temperature is difficult to control. Patent CN 113735673 A discloses a method for preparing cyclopropane high-energy fuels from olefins using diethylzinc catalyst. In this method, dicyclopentadiene is used as the substrate, and Al-MCM-41 molecular sieve is used as the catalyst, achieving cyclopropanation of dicyclopentadiene (yield 87.2%). This method requires the use of diethylzinc, which is highly flammable, and the catalyst dosage is as high as 50% of the olefin mass, resulting in poor atom economy.

[0004] Ionic liquids possess excellent properties, such as low vapor pressure, low volatility, stable existence, low melting point, high thermal and electrochemical stability, good solubility, and strong structural designability. All these unique properties enable ionic liquids to exhibit excellent catalytic performance. In Science 379, 807–811 (2023), chloroaluminate ionic liquids were used to catalyze the conversion of polyolefins to liquid alkanes; in Nature Sustainability 6, 1685–1692 (2023), chlorinated ionic liquids were used to catalyze the degradation of plastics; Nature Catalysis 4, 753–762 (2021) found that proton ionic liquids can modulate interfacial hydrogen bonds, thereby enhancing the ORR electrocatalytic process; and Nature Communications 14, 1457 (2023) found that ionic liquids and Co single atoms can improve the photocatalytic CO2 conversion process.

[0005] To address the aforementioned problems, this invention is proposed. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a method for the efficient preparation of dicyclopropane high-energy fuels by reacting olefins with CH2I2 using ionic liquid catalysis. This method utilizes dicyclopentadiene as a raw material and an ionic liquid as a catalyst to prepare dicyclopropane high-energy fuels with high selectivity, offering advantages such as high selectivity, good atom economy, and mild reaction conditions.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A method for preparing dicyclopropane high-energy fuel from olefins using ionic liquid catalysis involves mixing olefins, ionic liquid catalyst, Zn powder, carbene precursor CH2I2, and an organic solvent, stirring the mixture at a certain temperature for a period of time, filtering and separating the mixture after the reaction, and then using gas chromatography to determine the selectivity of the dicyclopropane high-energy fuel.

[0009] As a preferred embodiment of the present invention, the ionic liquid specifically includes, but is not limited to, one or more of the following: 1-butyl-3-methylimidazolium hexafluorophosphate, 1-butyl-3-methylimidazolium perchlorate, 1-butyl-3-methylimidazolium acetate, 1-butyl-3-methylimidazolium thiocyanate, 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt, 1-butyl-3-methylimidazolium p-methylbenzenesulfonate, 1-butyl-3-methylimidazolium trifluoromethanesulfonate, 1-butyl-3-methylimidazolium chloride, 1-butyl-3-methylimidazolium lactate, 1-butyl-3-methylimidazolium trifluoroacetate, N-butylpyridine trifluoroacetate, N-butyl,methylbenzimidazole trifluoroacetate, N-methyl,butylpyrrolidine trifluoroacetate, trimethylbutylammonium trifluoroacetate, and 1-vinyl-3-sulfobutylimidazolium trifluoromethanesulfonate.

[0010] As a preferred embodiment of the present invention, the reaction can be carried out at a temperature of 40-80°C for 0.5-6 hours, wherein CH2I2 is used as a carbene precursor.

[0011] In a preferred embodiment of the present invention, the raw material olefin can be one of dicyclopentadiene, isoprene, and 1,7-octadiene. The molar ratio of the olefin to zinc powder can be 1:2-10.

[0012] As a preferred embodiment of the present invention, the catalyst ionic liquid accounts for 1-15% of the molar amount of zinc powder, preferably 3-15%.

[0013] As a preferred embodiment of the present invention, the molar ratio of the olefin to the carbene precursor CH2I2 is 1:1-10.

[0014] As a preferred embodiment of the present invention, the organic solvent may be one or both of 1,4-dioxane and acetonitrile. 1-4 mL of organic solvent is added for every 1 mmol of olefin.

[0015] As a preferred embodiment of the present invention, 5 mmol of dicyclopentadiene, 0.5-1.5 mmol of ionic liquid, 10-50 mmol of zinc powder, 10-50 mmol of CH2I2, and 5-20 mL of 1,4-dioxane are added to a flask and reacted at 40-80°C for 4 hours. After the reaction is completed, the mixture is filtered and separated to obtain dicyclopropane high-energy fuel. The specific reaction equation is shown below.

[0016]

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0018] This invention provides a method for preparing bicyclopropane high-energy fuels from olefins using ionic liquid catalysis. Compared with protic acid catalysts, the ionic liquid catalyst used in this invention is less volatile and the reaction process is more stable. In addition, compared with the prior art, the method of this invention has the advantages of good atom economy, low catalyst dosage, mild reaction conditions, and high selectivity for bicyclopropane products.

[0019] The method of this invention utilizes dicyclopentadiene, isoprene and 1,7-octadiene as olefin raw materials and ionic liquid as catalyst to prepare dicyclopropane high-energy fuel with high selectivity. It has the advantages of high selectivity, good atom economy and mild reaction conditions. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0021] In the following examples, all raw materials used are common commercially available products that can be purchased directly, or can be prepared using conventional techniques in the art.

[0022] Example 1

[0023] Add 5 mL of 1,4-dioxane solvent, 30 mmol of Zn powder, 0.9 mmol of 1-butyl-3-methylimidazolium trifluoroacetate, 5 mmol of dicyclopentadiene, and 30 mmol of CH2I2 to a 50 mL flask, and react at 60 °C for 4 h.

[0024] After the reaction was completed, the mixture was filtered and separated. Gas chromatography was used to determine that the conversion rate of dicyclopentadiene was 100%, and the selectivity of dicyclopropane high-energy fuel was 79.2%.

[0025] Example 2

[0026] Add 5 mL of 1,4-dioxane solvent, 30 mmol of Zn powder, 0.9 mmol of 1-butyl-3-methylimidazolium chloride, 5 mmol of dicyclopentadiene, and 30 mmol of CH2I2 to a 50 mL flask, and react at 60 °C for 4 h.

[0027] After the reaction was completed, the mixture was filtered and separated. Gas chromatography was used to determine that the conversion rate of dicyclopentadiene was 100%, and the selectivity of dicyclopropane high-energy fuel was 74.8%.

[0028] Example 3

[0029] Add 5 mL of 1,4-dioxane solvent, 30 mmol of Zn powder, 0.9 mmol of 1-butyl-3-methylimidazolium lactate, 5 mmol of dicyclopentadiene, and 30 mmol of CH2I2 to a 50 mL flask, and react at 60 °C for 4 h.

[0030] After the reaction was completed, the mixture was filtered and separated. Gas chromatography was used to determine that the conversion rate of dicyclopentadiene was 100%, and the selectivity of dicyclopropane high-energy fuel was 82.8%.

[0031] Example 4

[0032] Add 5 mL of 1,4-dioxane solvent, 30 mmol of Zn powder, 0.9 mmol of N-butyl,methylbenzimidazole trifluoroacetate (purchased from Shanghai Chengjie Chemical Co., Ltd.), 5 mmol of dicyclopentadiene, and 30 mmol of CH2I2 to a 50 mL flask, and react at 60 °C for 4 h.

[0033] After the reaction was completed, the mixture was filtered and separated. The conversion rate of dicyclopentadiene was 100% and the selectivity of dicyclopropane high-energy fuel was 83.8% as determined by gas chromatography.

[0034] Example 5

[0035] Add 5 mL of 1,4-dioxane solvent, 30 mmol of Zn powder, 0.9 mmol of N-butyl,methylbenzimidazole trifluoroacetate, 5 mmol of dicyclopentadiene, and 30 mmol of CH2I2 to a 50 mL flask, and react at 70 °C for 4 h.

[0036] After the reaction was completed, the mixture was filtered and separated. Gas chromatography was used to determine that the conversion rate of dicyclopentadiene was 100%, and the selectivity of dicyclopropane high-energy fuel was 85%.

[0037] Example 6

[0038] Add 5 mL of 1,4-dioxane solvent, 30 mmol of Zn powder, 0.9 mmol of N-butyl,methylbenzimidazole trifluoroacetate, 5 mmol of dicyclopentadiene, and 20 mmol of CH2I2 to a 50 mL flask, and react at 70 °C for 4 h.

[0039] After the reaction was completed, the mixture was filtered and separated. The conversion rate of dicyclopentadiene was 100% and the selectivity of dicyclopropane high-energy fuel was 91.2% as determined by gas chromatography.

[0040] Example 7

[0041] Add 5 mL of 1,4-dioxane solvent, 30 mmol of Zn powder, 1 mmol of N-butyl, methylbenzimidazole trifluoroacetate, 5 mmol of dicyclopentadiene, and 20 mmol of CH2I2 to a 50 mL flask, and react at 70 °C for 4 h.

[0042] After the reaction was completed, the mixture was filtered and separated. Gas chromatography was used to determine that the conversion rate of dicyclopentadiene was 100%, and the selectivity of dicyclopropane high-energy fuel was 95%.

[0043] Example 8

[0044] Add 5 mL of 1,4-dioxane solvent, 35 mmol of Zn powder, 1 mmol of N-butyl, methylbenzimidazole trifluoroacetate, 5 mmol of dicyclopentadiene, and 20 mmol of CH2I2 to a 50 mL flask, and react at 70 °C for 4 h.

[0045] After the reaction was completed, the mixture was filtered and separated. Gas chromatography was used to determine that the conversion rate of dicyclopentadiene was 100%, and the selectivity of dicyclopropane high-energy fuel was 97.2%.

[0046] Example 9

[0047] Add 10 mL of 1,4-dioxane solvent, 35 mmol of Zn powder, 1 mmol of N-butyl, methylbenzimidazole trifluoroacetate, 5 mmol of dicyclopentadiene, and 20 mmol of CH2I2 to a 50 mL flask, and react at 70 °C for 4 h.

[0048] After the reaction was completed, the mixture was filtered and separated. Gas chromatography was used to determine that the conversion rate of dicyclopentadiene was 100%, and the selectivity of dicyclopropane high-energy fuel was 79.9%.

[0049] Example 10

[0050] Add 5 mL of 1,4-dioxane solvent, 35 mmol of Zn powder, 1 mmol of N-butyl, methylbenzimidazole trifluoroacetate, 5 mmol of dicyclopentadiene, and 20 mmol of CH2I2 to a 50 mL flask, and react at 70 °C for 1 h.

[0051] After the reaction was completed, the mixture was filtered and separated. The conversion rate of dicyclopentadiene was determined to be 99.5% by gas chromatography, and the selectivity of dicyclopropane high-energy fuel was 80.1%.

[0052] Example 11

[0053] Add 5 mL of 1,4-dioxane solvent, 35 mmol of Zn powder, 1 mmol of N-butyl, methylbenzimidazole trifluoroacetate, 5 mmol of dicyclopentadiene, and 20 mmol of CH2I2 to a 50 mL flask, and react at 70 °C for 3 h.

[0054] After the reaction was completed, the mixture was filtered and separated. Gas chromatography was used to determine that the conversion rate of dicyclopentadiene was 100%, and the selectivity of dicyclopropane high-energy fuel was 95.8%.

[0055] Example 12

[0056] Add 5 mL of 1,4-dioxane solvent, 35 mmol of Zn powder, 1 mmol of N-butyl, methylbenzimidazole trifluoroacetate, 5 mmol of isoprene, and 20 mmol of CH2I2 to a 50 mL flask, and react at 70 °C for 6 h.

[0057] After the reaction was completed, the mixture was filtered and separated. Gas chromatography was used to determine that the isoprene conversion rate was 99.7% and the selectivity for dicyclopropane high-energy fuel was 94.6%.

[0058] Comparative Example 1

[0059] To compare the catalytic effect of ionic liquids, a comparative experiment without a catalyst was conducted.

[0060] Add 30 mmol of 1,4-dioxane solvent, 30 mmol of Zn powder, 5 mmol of dicyclopentadiene, and 30 mmol of CH2I2 to a 50 mL flask, and react at 60 °C for 4 h.

[0061] After the reaction was completed, the mixture was filtered and separated. The yield of the bicyclopropane high-energy fuel in the organic phase was determined by gas chromatography. The results showed that no cyclic products were formed.

[0062] Comparative Example 2

[0063] To compare the catalytic effects of Zn-Cu alginate, a comparative experiment on Zn-Cu alginate catalysis was conducted.

[0064] Add 5 mL of 1,4-dioxane solvent, 30 mmol of Zn-Cu, 5 mmol of dicyclopentadiene, and 30 mmol of CH2I2 to a 50 mL flask, and react at 60 °C for 4 h.

[0065] After the reaction was completed, the mixture was filtered and separated. The conversion rate of dicyclopentadiene was determined to be 100% by gas chromatography, and the selectivity of dicyclopropane high-energy fuel was 41.4%.

[0066] In summary, the method of this invention is simple to operate, reacts rapidly, and can obtain high-purity dicyclopropane high-energy fuel. Compared with protonic acid catalysts, it also has advantages such as catalyst stability and less environmental harm. The conversion rate of dicyclopentadiene is close to 100%, and the highest selectivity of dicyclopropane high-energy fuel reaches 97.2%.

[0067] The above description is merely a specific implementation step of this invention, but the scope of protection of this invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this invention should be included within the scope of protection of this invention.

Claims

1. A method for preparing dicyclopropane high-energy fuel from olefins using ionic liquid catalysis, characterized in that, An olefin, ionic liquid, Zn powder, carbene precursor CH2I2, and organic solvent are mixed and reacted at a certain temperature for a period of time. After the reaction is completed, the mixture is filtered and separated to obtain a dicyclopropane high-energy fuel. The ionic liquid comprises one or more of the following: 1-butyl-3-methylimidazolium hexafluorophosphate, 1-butyl-3-methylimidazolium perchlorate, 1-butyl-3-methylimidazolium acetate, 1-butyl-3-methylimidazolium thiocyanate, 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1-butyl-3-methylimidazolium p-methylbenzenesulfonate, 1-butyl-3-methylimidazolium trifluoromethanesulfonate, 1-butyl-3-methylimidazolium chloride, 1-butyl-3-methylimidazolium lactate, 1-butyl-3-methylimidazolium trifluoroacetate, and N-butyl,methylbenzimidazole trifluoroacetate. React at 40-80℃ for 0.5-6 hours; The olefin is one of dicyclopentadiene, isoprene, and 1,7-octadiene.

2. The method for preparing dicyclopropane high-energy fuels from olefins using ionic liquid catalysis as described in claim 1, characterized in that, The molar ratio of the olefin to zinc powder is 1:2-10.

3. The method for preparing dicyclopropane high-energy fuels from olefins using ionic liquid catalysis as described in claim 1, characterized in that, The ionic liquid accounts for 1-15% of the molar amount of zinc powder.

4. The method for preparing dicyclopropane high-energy fuel from olefins using ionic liquid catalysis as described in claim 1, characterized in that, The molar ratio of the olefin to CH2I2 is 1:1-10.

5. The method for preparing dicyclopropane high-energy fuels from olefins using ionic liquid catalysis as described in claim 1, characterized in that, The organic solvent is one or both of 1,4-dioxane and acetonitrile.

6. The method for preparing dicyclopropane high-energy fuels from olefins using ionic liquid catalysis as described in claim 5, characterized in that, For every 1 mmol of olefin, add 1-4 mL of organic solvent.

Images