A bi-pyrazole energetic compound and a preparation method thereof

Abstract

The application discloses 3,4'-bipyrazole and an energetic compound thereof, which is further functionalized by introducing an energetic group on a 3,4'-bipyrazole skeleton; and a preparation method of the 3,4'-bipyrazole and the energetic compound thereof, which realizes synthesis of the novel bipyrazole energetic compound through a multi-step reaction from raw materials easy to prepare, has great potential for use as a high-energy material, and provides a new idea for synthesizing novel high-energy energetic compounds in the synthesis of energetic materials.

Description

Technical Field

[0001] This invention relates to the field of energetic materials technology, specifically to bipyrazole-based energetic compounds and their preparation methods. Background Technology

[0002] High-energy materials play an indispensable role in both military defense and civilian technology, demonstrating exceptional value in driving aerospace technology innovation, improving mining efficiency, and enriching the expression of fireworks art. With the continuous development of high-energy-density materials (HEDM) applications, the pursuit of superior performance and molecular structural stability have become two core elements for evaluating their overall effectiveness. Compared to traditional energetic compound systems, nitrogen-rich heterocyclic molecules stand out due to their unique chemical structure. Their nitrogen content is significantly higher than the carbon and hydrogen content in traditional compounds, giving these molecules a higher potential for formation enthalpy. In particular, the bipyrazole molecular skeleton, as a prime example of a class of high-energy-density chemical bonds rich in N-N, CN, and C=N bonds, features a widely distributed conjugated planar large π-bond structure. This not only effectively improves the heat of explosion and unit specific impulse performance but also significantly enhances the thermal stability of the molecule, thus ensuring superior performance and low mechanical sensitivity in complex application environments. Furthermore, introducing explosive groups such as nitro groups into the bipyrazole molecular skeleton can further improve the energy performance of the compound. The synthesis of bipyrazole-based energetic compounds has become one of the research hotspots in the field of energetic materials in recent years. Summary of the Invention

[0003] The purpose of this invention is to provide a tetranitrobipyrazole energetic compound based on a 3,4'-bipyrazole compound, as well as an aminotetranitrobipyrazole. A novel bipyrazole skeleton can be obtained in one step through a cyclization reaction of bipyrimidine. Subsequently, the 3,4'-bipyrazole is further functionalized through nitration and amination reactions of the bipyrazole skeleton, effectively improving the thermal stability and detonation performance of these energetic compounds, making them more advantageous in energetic material applications.

[0004] Another object of the present invention is to provide a method for preparing the aforementioned novel 3,4'-bipyrazole compounds, tetranitrobipyrazole energetic compounds, and aminotetranitrobipyrazoles. This method successfully synthesizes tetranitrobipyrazole energetic compounds through a multi-step reaction starting from known and available raw materials. The synthesized bipyrazole energetic compounds have great potential as high-energy materials.

[0005] The 3,4'-bipyrazole compound mentioned in the technical solution of this invention has the following structural formula: Tetranitrobipyrazole energetic compound: Structural formula Aminotetronitrobipyrazole Energetic Compound: Structural Formula

[0006] The preparation method of 3',4,5,5'-tetranitro-1'H,2H-[3,4'-bipyrazole]-1',2-diamine energetic material specifically includes the following steps:

[0007] 1) The step of preparing 3,4'-bipyrazole (compound 1) by adding 4,5'-bipyrimidine to toluene at room temperature, then adding trifluoromethanesulfonic anhydride to it, reacting at room temperature for 2 hours, adding hydrazine hydrate, raising the temperature to 60 degrees and continuing the reaction for 24 hours.

[0008]

[0009] 2) The step of reacting 3,4'-bipyrazole with a nitrifying agent to generate tetranitro-3,4'-bipyrazole (compound 2);

[0010]

[0011] 3) The step of preparing compound 3 by reacting compound 2 with an amination reagent.

[0012]

[0013] Preferably, in step 1), the concentration of hydrazine hydrate used can be either 80 wt% or 85 wt%, and the molar ratio of 4,5'-bipyrimidine to trifluoromethanesulfonic anhydride, water, and hydrazine is 1:2:4 to 1:10:20.

[0014] Preferably, in step 2), in the potassium nitrate / sulfuric acid nitration system, the sulfuric acid can be any one of concentrated sulfuric acid or 20wt% fuming sulfuric acid, and the mass ratio of compound 1 to potassium nitrate and sulfuric acid is 1:10:30 to 1:10:60.

[0015] Preferably, in step 3), the reaction is carried out in the presence of an alkaline substance, using acetonitrile as the reaction solvent. The alkaline substance can be any one of potassium hydroxide, sodium bicarbonate, or 1,8-diazabicyclopentane-dec-7-ene (DBU).

[0016] Preferably, in step 3), the amination agent can be either hydroxylamine sulfonic acid or O-p-toluenesulfonyl hydroxylamine.

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

[0018] (1) This invention uses a one-step method to synthesize a novel 3,4'-bipyrazole skeleton, which greatly shortens the synthesis steps compared with traditional pyrazole synthesis methods. For example, the synthesis of 3,3'-bipyrazole requires at least 3 steps and the use of highly toxic, high-concentration hydrazine hydrate, while the synthesis of 4,4'-bipyrazole requires at least 7 steps. However, this synthesis method only requires 1 step to obtain the target molecule. At the same time, compared with the reported 3,4'-bipyrazole synthesis methods, the yield is also greatly improved, approximately three times that of the reported methods. Thus, this method greatly improves the synthesis efficiency of bipyrazole and does not require the use of highly toxic substances as synthetic raw materials, further improving the safety of the reaction and laying the foundation for future industrial production.

[0019] (2) This invention introduces energetic groups to achieve nitrogen-amino functionalization by utilizing the reactivity of nitrogen-hydrogen bonds in the bipyrazole skeleton, further functionalizing the 3,4'-bipyrazole skeleton. The thermal decomposition temperatures of energetic molecules 2 and 3 are both above 250 degrees Celsius. While exhibiting good thermal stability, the detonation velocities of the two molecules reach 8173 m·s, respectively. -1 With 8355m·s -1 It is much greater than the detonation velocity of the classic explosive TNT (7005 m / s). -1 This demonstrates that it effectively improves the thermal stability and detonation performance of energetic compounds, making them more advantageous in the application of energetic materials. Attached Figure Description

[0020] Figure 1 The image shows the carbon NMR spectrum of compound 2 in Example 1 of this invention.

[0021] Figure 2 The above is the 1H NMR spectrum of compound 3 in Example 1 of this invention;

[0022] Figure 3 The image shows the carbon NMR spectrum of compound 3 in Example 1 of this invention.

[0023] Figure 4 This is a single-crystal structure diagram of compound 2 in Example 1 of the present invention;

[0024] Figure 5 This is a single-crystal structure diagram of compound 3 in Example 1 of the present invention. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this invention clearer, a more detailed description is provided below with reference to the accompanying drawings and specific embodiments. It should be understood that the described specific embodiments are merely for explaining this patent and are not intended to limit the invention.

[0026] Example 1

[0027] Bipyrazole energetic compound 3 has the following structural formula:

[0028]

[0029] The specific synthesis route is as follows:

[0030]

[0031] The specific synthesis steps are as follows:

[0032] Step 1: Synthesis of Compound 1

[0033] 4,5'-Bipyrimidine (0.1 mmol) was dissolved in toluene (1.0 mL), and nitrogen was introduced to replace the nitrogen atmosphere. Trifluoromethanesulfonic anhydride (0.25 mmol) was added, and the mixture was reacted at room temperature for 2 hours. Then, 80% hydrazine hydrate (0.6 mmol) was added, and the reaction mixture was reacted at 60°C for 24 hours. The reaction was monitored by thin-layer chromatography. After the reaction was completed, the mixture was cooled to room temperature, concentrated, and purified by column chromatography to give compound 1 (60% yield).

[0034] Step 2: Synthesis of Compound 2

[0035] Potassium nitrate (10.0 g) was slowly added in portions to concentrated sulfuric acid (60.0 g) at 0 °C, followed by the slow addition of compound 1 (1.0 g) in portions to the nitration system. After the addition was complete, the temperature was raised to 100 °C and the reaction was continued at this temperature for 48 hours. After the reaction was completed, the reaction solution was quenched in 100 mL of ice water and extracted with diethyl ether. The organic phases were combined, concentrated to remove the organic solvent, and compound 2 (50% yield) was obtained.

[0036] Step 3: Synthesis of Compound 3

[0037] At 0 °C, 2.0 mmol of 1,8-diazabicycloundec-7-ene was added to a 7.5 mL solution of compound 2 (1.0 mmol). The reaction was continued for 30 min, and then 2.4 mmol of freshly prepared O-p-toluenesulfonylhydroxylamine was added. The reaction was brought back to room temperature and monitored by thin-layer chromatography. After the reaction was complete, the solvent was removed, and the compound was purified by column chromatography to give compound 3 (60% yield).

[0038] Example 2

[0039] The physicochemical properties of the energetic compounds 2 and 3 synthesized in the embodiments of the present invention are shown in Table 1.

[0040] Table 1: Physicochemical properties of compounds 2 and 3

[0041]

[0042] The table above shows that energetic compounds 2 and 3 have good thermal stability and detonation performance. For energetic materials, the enthalpy of formation and density jointly determine the detonation velocity and detonation pressure. Detonation velocity and detonation pressure are key to the performance of energetic materials, and the higher the better. Impact sensitivity and friction sensitivity are key to whether they can be used. The higher the sensitivity, the more insensitive the material. Insensitive energetic materials have good stability and are safer to use and store. It can be seen that these two new compounds have great potential to become high-energy materials.

[0043] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. It can be applied to various fields suitable for the present invention. Other modifications can be readily made by those skilled in the art. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and examples shown and described herein.

Claims

1. A tetranitro bis-pyrazole energetic compound characterized in that, The energetic compound of tetranitro-bipyrazole is a compound based on 3,4'-bipyrazole, and has the following structure (II):

2. An amine-based tetranitrohydrazine energetic compound characterized by, The energetic compound of tetranitro-bipyrazole is a compound based on 3,4'-bipyrazole, and has the following structure (II):

3. A process for the preparation of the hydrazine-containing compound according to any one of claims 1 or 2, characterized in that, The method comprises the following steps: Step one, synthesis of the bipyrazole compound of formula (I) The bipyrazole compound of formula (I) is synthesized from 4,5'-bipyrimidine through a cyclization reaction. Step two, synthesis of the tetranitro-bipyrazole compound of formula (II) The bipyrazole compound of formula (I) obtained in step one is used as a raw material to obtain the tetranitro-bipyrazole compound of formula (II) through a nitration reaction. Step three, synthesis of the amido-tetranitro-bipyrazole compound of formula (III) The tetranitro-bipyrazole compound of formula (II) obtained in step two is reacted with an aminating agent to obtain the amido-tetranitro-bipyrazole compound of formula (III).

4. The method as claimed in claim 3, characterized in that, In step one, the reaction for synthesizing the bipyrazole compound of formula (I) from 4,5'-bipyrimidine comprises: In toluene, 4,5'-bipyrimidine is reacted with hydrazine hydrate and trifluoromethanesulfonic anhydride to obtain the bipyrazole compound of formula (I).

5. The method as claimed in claim 3, wherein, In step two, the reaction for synthesizing the tetranitro-bipyrazole compound of formula (II) from the bipyrazole compound of formula (I) through a nitration reaction comprises: The bipyrazole compound of formula (I) is added to a nitration system of KNO3 / H2SO4 to prepare the tetranitro-bipyrazole compound of formula (II).

6. The method as claimed in claim 3, wherein, In step three, the reaction for preparing the amido-tetranitro-bipyrazole compound of formula (III) from the tetranitro-bipyrazole compound of formula (II) comprises: At zero degree, 1,8-diazabicycloundec-7-ene is added dropwise to a solution of the tetranitro-bipyrazole compound of formula (II) in acetonitrile, and stirring is continued at this temperature for 30 min, then the aminating agent is added dropwise to the reaction mixture, and reaction is carried out at room temperature until the raw material disappears to obtain the amido-tetranitro-bipyrazole compound of formula (III).

7. The method of claim 4, wherein, The reaction temperature is room temperature to 60 degrees Celsius, and the reaction time is at least 24 hours.

8. The method of claim 5, wherein, The reaction temperature is 100 degrees Celsius, and the reaction time is at least 48 hours.

9. The method of claim 6, wherein, The aminating agent is any one of hydroxylamine sulfonic acid or O-p-toluenesulfonylhydroxylamine.

10. The method as claimed in claim 3, wherein, The bipyrazole compound of formula (I) has the following structure:

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