Diazidomethyl isoxazole energetic compound and synthesis method and application thereof

Abstract

The application discloses a kind of diazomethyl isoxazole energetic compounds and synthesis method thereof, its structural formula is as shown in formula (I).The application also provides the synthesis method of the compound.The energetic compound disclosed in the application is liquid at room temperature, the thermal decomposition temperature is 204 DEG C, the heat of formation is 739.64 kJ / mol, and it has good application potential in energetic plasticizer.

Description

Technical Field

[0001] This invention belongs to the field of energetic materials technology, specifically relating to an energetic compound of diazidomethylisoxazole, its synthesis method, and its application. Background Technology

[0002] Energetic materials are indispensable for weapon systems, serving as the energy carrier for efficient damage in conventional weapon systems and the power source for long-range weapon delivery and gun firing. Among them, energetic compounds with low melting points have broad application prospects in cast-carrier explosives and energetic plasticizers. Energetic plasticizers are particularly indispensable in propellants and solid propellants.

[0003] Traditional energetic plasticizers are mostly energetic derivatives with aliphatic skeletons, which lack sufficient sensitivity and stability. Therefore, there is an urgent need to design and synthesize novel low-melting-point energetic compounds. Novel energetic compounds with nitrogen heterocycles as the core skeleton have always been a research hotspot in the field of energetic materials. Currently, many promising high-energy-density energetic materials contain at least one nitrogen heterocycle structural unit. Isoxazole heterocycles possess high-energy NO, CO, and C=N bonds, giving the entire molecule a high positive enthalpy of formation. They exhibit unique characteristics of low C-H and high nitrogen content, easily achieving oxygen equilibrium, and their decomposition products are mainly nitrogen gas, making them easy to construct novel environmentally friendly energetic materials.

[0004] Currently, the overall performance of isoxazole heterocyclic nitrate-containing energetic plasticizers is not entirely satisfactory. Compounds with high heat of formation often have problems such as high sensitivity and poor safety and thermal stability, such as 5-(nitrate ester)-isooxazole-3-carboxylic acid ethyl ester and isoxazole-3,5-bis(methylene) dinitrate reported by Wingard et al. (Chempluschem. 2017, 82(2), 195-198). Other compounds have the problem of high heat of formation but low energy level.

[0005] In summary, there is an urgent need in this field for an isoxazole energetic compound with a low melting point, high heat of formation and excellent thermal stability, and a method for its preparation. Summary of the Invention

[0006] To address the shortcomings of existing technologies, one objective of this invention is to provide an energetic compound containing diazidomethylisoxazole, which has a thermal decomposition temperature of 204°C. o C. The heat of formation is 739.64 kJ / mol, and its chemical structural formula is shown in formula <Ⅰ>:

[0007] ;

[0008] <Ⅰ>.

[0009] Another object of the present invention is to provide a method for synthesizing the above-mentioned diazidomethylisoxazole energetic compound, the method comprising the following steps:

[0010] (1) Add fuming nitric acid to acetic anhydride at 0℃~5℃, stir for 30 min, add 3,5-dihydroxymethylisoxazole, keep warm at 25℃~35℃ for 1h~2h, then pour the reaction solution into a large amount of ice water to cool down, stir continuously, add extractant to extract, wash, and distill to obtain 3,5-dinitrate ester isoxazole;

[0011] (2) Add the reaction solvent to the reaction flask, then add 3,5-dinitrate methylisoxazole and sodium azide. After the addition is complete, heat to 80℃~100℃ and react for 2h~4h. Cool to room temperature, add organic solvent for extraction, washing and distillation to obtain 3,5-diazidomethylisoxazole.

[0012] In a preferred embodiment of the present invention, in step (1), the volume ratio of acetic anhydride to fuming nitric acid is 6 to 8:1.

[0013] As a preferred embodiment of the present invention, in step (1), the molar ratio of fuming nitric acid to 3,5-dihydroxymethylisoxazole is 2.2~3.0:1.

[0014] As a preferred embodiment of the present invention, in step (1), the extractant is any one of diethyl ether, dichloromethane, ethyl acetate, isopropyl acetate, chloroform, and butyl acetate.

[0015] As a preferred embodiment of the present invention, when performing step (2), the organic solvent is any one of diethyl ether, dichloromethane, ethyl acetate, isopropyl acetate, and chloroform.

[0016] As a preferred embodiment of the present invention, in step (2), the reaction solvent is a mixture of water and any one of dimethylformamide, ethanol, isopropanol, n-propanol and ethylene glycol, preferably a mixture of water and ethanol.

[0017] In a preferred embodiment of the present invention, in step (2), the molar ratio of 3,5-dinitrate isoxazole to sodium azide is 1:2.2~2.6.

[0018] In a preferred embodiment of the present invention, the extractant in step (2) is ethyl acetate.

[0019] Another object of the present invention is to provide the application of the above-mentioned azidomethylisoxazole energetic compound in propellants and solid propellants.

[0020] The beneficial effects of this invention: The thermal decomposition temperature of the diazidomethylisoxazole energetic compound of this invention is 204 °C.o C. The heat of formation is 739.64 kJ·mol⁻¹ -1 . Detailed Implementation

[0021] The present invention will be specifically described below through embodiments. It should be noted that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the above-described invention are still within the scope of protection of the present invention. Example

[0022] A diazidomethylisoxazole energetic compound, the chemical structural formula of which is shown in Formula <Ⅰ> below:

[0023] ;

[0024] <Ⅰ>.

[0025] The synthesis method of the above-mentioned diazidomethylisoxazole energetic compound includes the following steps:

[0026] (1) 4.2 mL (0.09 mol) of fuming nitric acid was added to 29 mL of acetic anhydride at 0℃~5℃. After stirring for 30 min, 3.87 g (0.03 mol) of 3,5-dihydroxymethylisoxazole was added. After the addition was complete, the mixture was kept at 30℃ for 1 h. Then the reaction solution was poured into a large amount of ice water and stirred continuously. Diethyl ether was added for extraction, washing, and distillation to obtain 5.72 g of 3,5-dinitrate isoxazole, with a yield of 87% and a purity of 98.5%.

[0027] (2) Add 15 mL of ethanol and 15 mL of water to the reaction flask, then add 2.19 g (0.01 mol) of 3,5-diazidoxymethylisoxazole and 1.69 g (0.026 mol) of sodium azide in sequence. After the addition is complete, heat to 80 °C and react for 3 h. Cool to room temperature, add ethyl acetate for extraction, wash and distill to obtain 1.63 g of 3,5-diazidoxymethylisoxazole with a yield of 91% and a purity of 99.3%.

[0028] Product structure identification:

[0029] Infrared spectroscopy: FT-IR (cm) -1 ), u : 3219, 2937, 2884, 2107, 1642, 1521, 1483,1358, 1280, 1174, 961, 842, 823, 795, 761, 601.

[0030] Nuclear magnetic resonance spectroscopy:1 H NMR (DMSO-d6, 600 MHz), d : 6.36 (s, 1H), 4.48(s, 2H), 4.44(s, 2H); 13 CNMR (DMSO-d6, 150 MHz), d : 167.81, 159.56, 102.36, 45.61, 45.44.

[0031] The above structural identification data confirms that the obtained substance is 3,5-diazidomethylisoxazole.

[0032] Properties of 3,5-diazidomethylisoxazole:

[0033] Appearance: Pale yellow liquid;

[0034] Peak decomposition temperature: 204 o C;

[0035] Measured impact sensitivity: 20 J;

[0036] Enthalpy of formation: 739.64 kJ mol -1 .

[0037] Based on the above properties, the energetic compound provided by the present invention has great application potential in propellants and launchers. Example

[0038] (1) At 0℃~5℃, 3.4 ml (0.09 mol) of fuming nitric acid was added to 24 mL of acetic anhydride. After stirring for 30 min, 3.87 g (0.03 mol) of 3,5-dihydroxymethylisoxazole was added. After the addition was complete, the mixture was kept at 30℃ for 1 h. Then, the reaction solution was poured into a large amount of ice water and stirred continuously. Dichloromethane was added for extraction, washing, and distillation to obtain 5.85 g of 3,5-dinitrate isoxazole, with a yield of 89% and a purity of 98.7%.

[0039] (2) Add 15 mL of ethanol and 15 mL of water to the reaction flask, then add 2.19 g (0.01 mol) of 3,5-diazidoxymethylisoxazole and 1.56 g (0.024 mol) of sodium azide in sequence. After the addition is complete, heat to 80 °C and react for 3 h. Cool to room temperature, add isopropyl acetate for extraction, washing and distillation to obtain 1.66 g of 3,5-diazidoxymethylisoxazole with a yield of 93% and a purity of 99.1%.

[0040] The reaction phenomena observed during the preparation process in this embodiment are the same as those in Example 1.

[0041] The structural identification results of the product obtained in this embodiment are the same as those in Example 1. Example

[0042] (1) At 0℃~5℃, 5.1 ml (0.135 mol) of fuming nitric acid was added to 36 mL of acetic anhydride. After stirring for 30 min, 5.81 g (0.045 mol) of 3,5-dihydroxymethylisoxazole was added. After the addition was complete, the mixture was kept at 30℃ for 1 h. Then, the reaction solution was poured into a large amount of ice water and stirred continuously. Dichloromethane was added for extraction, washing, and distillation to obtain 8.7 g of 3,5-dinitrate isoxazole with a yield of 88% and a purity of 98.3%.

[0043] (2) Add 15 mL of ethanol and 15 mL of water to the reaction flask, then add 3.29 g (0.015 mol) of 3,5-diazidoxymethylisoxazole and 2.34 g (0.036 mol) of sodium azide in sequence. After the addition is complete, heat to 80 °C and react for 3 h. Cool to room temperature, add ethyl acetate for extraction, wash and distill to obtain 2.47 g of 3,5-diazidoxymethylisoxazole with a yield of 92% and a purity of 99.2%.

[0044] The reaction phenomena observed during the preparation process in this embodiment are the same as those in Example 1.

[0045] The structural identification results of the product obtained in this embodiment are the same as those in Example 1. Example

[0046] (1) At 0℃~5℃, 5.1 ml (0.135 mol) of fuming nitric acid was added to 36 mL of acetic anhydride. After stirring for 30 min, 5.81 g (0.045 mol) of 3,5-dihydroxymethylisoxazole was added. After the addition was complete, the mixture was kept at 30℃ for 1 h. Then, the reaction solution was poured into a large amount of ice water and stirred continuously. Ethyl acetate was added for extraction, washing, and distillation to obtain 8.77 g of 3,5-dinitrate isoxazole, with a yield of 89% and a purity of 98.2%.

[0047] (2) Add 15 mL of ethanol and 15 mL of water to the reaction flask, then add 3.29 g (0.015 mol) of 3,5-diazidoxymethylisoxazole and 2.34 g (0.036 mol) of sodium azide in sequence. After the addition is complete, heat to 80 °C and react for 3 h. Cool to room temperature, add dichloromethane for extraction, washing and distillation to obtain 2.44 g of 3,5-diazidoxymethylisoxazole with a yield of 91% and a purity of 99.4%.

[0048] The reaction phenomena observed during the preparation process in this embodiment are the same as those in Example 1.

[0049] The structural identification results of the product obtained in this embodiment are the same as those in Example 1.

Claims

1. A diazidomethylisoxazole energetic compound, characterized in that, The chemical structural formula of the energetic compound is shown in formula <Ⅰ> below: ； <Ⅰ>。 2. The method for synthesizing the diazidomethylisoxazole energetic compound according to claim 1, characterized in that, The method includes the following steps: (1) Add fuming nitric acid to acetic anhydride at 0℃~5℃, stir for 30 min, then add 3,5-dihydroxymethylisoxazole, keep warm at 25℃~35℃ for 1h~2h, then cool the reaction solution, stir continuously, add extractant to extract, wash and distill to obtain 3,5-dinitrate ester isoxazole; (2) Dissolve the 3,5-dinitrate ester isoxazole obtained in step (1) in the reaction solvent, then add sodium azide, heat to 80℃~100℃ and react for 2h~4h, cool to room temperature, add organic solvent for extraction, washing and distillation to obtain 3,5-diazidomethyl isoxazole.

3. The synthesis method according to claim 2, characterized in that, In step (1), the volume ratio of acetic anhydride to fuming nitric acid is 6 to 8:

1.

4. The synthesis method according to claim 2, characterized in that, In step (1), the molar ratio of fuming nitric acid to 3,5-dihydroxymethylisoxazole is 2.2~3.0:

1.

5. The synthesis method according to claim 2, characterized in that, In step (1), the extractant is any one of diethyl ether, dichloromethane, ethyl acetate, isopropyl acetate, chloroform, and butyl acetate.

6. The synthesis method according to claim 2, characterized in that, In step (2), the organic solvent is any one of diethyl ether, dichloromethane, ethyl acetate, isopropyl acetate, and chloroform.

7. The synthesis method according to claim 2, characterized in that, In step (2), the reaction solvent is a mixture of water and any one of dimethylformamide, ethanol, isopropanol, n-propanol, or ethylene glycol.

8. The synthesis method according to claim 2, characterized in that, In step (2), the molar ratio of 3,5-dinitrate isoxazole to sodium azide is 1:2.2~2.

6.

9. The use of the azidomethylisoxazole energetic compound of claim 1 or the azidomethylisoxazole energetic compound prepared by the synthetic method of any one of claims 2-8 in a propellant or propellant.

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