A high-energy, low-sensitivity energetic compound and its preparation method

Abstract

The present invention discloses a high-energy, low-sensitivity energetic compound and a preparation method thereof, comprising: using 3,5-diamino-4-nitropyrazole as a raw material, first cutting the C-N bond on the pyrazole ring under the action of an oxidant, removing a molecule of nitrogen to obtain a free radical intermediate, and then obtaining an intermediate product through a free radical coupling reaction; the intermediate product is refluxed under acidic conditions, and further obtaining a compound 2,5,7-triamino-3,6-dinitropyrazole [1,5- a Pyrimidine; in an acidic system, this compound undergoes an oxidation reaction with an oxidizing agent or a nitrating agent to obtain a target compound. This target compound has high energy, low sensitivity, and good thermal stability, and is a potential energetic material with application value.

Description

Technical Field

[0001] The present invention belongs to the field of energetic materials, and in particular relates to energetic organic compounds and preparation methods thereof. Background Art

[0002] Nitrogen-containing heterocyclic skeletons are widely present in biomolecules, natural products, and energetic materials, and their molecular frameworks hold significant research applications in organic synthesis. Consequently, the construction of functionalized nitrogen-containing heterocycles has attracted widespread interest among synthetic chemists. Among the most attractive methods for constructing these heterocycles, C-N bond activation and denitrogenation cyclization are among the most attractive. These reactions offer a clever way to synthesize specific fused rings that are difficult to prepare using traditional methods.

[0003] One of the strategies to achieve CN bond activation is transition metal-catalyzed CN bond cleavage. Transition metals, including Cu, Pd, and Ni, all exhibit high catalytic reactivity and can catalyze CN bond cleavage under simple and mild conditions. However, transition metal-catalyzed CN bond cleavage reactions are mainly concentrated on fused heterocycles. In addition, the use of metal catalysts usually leads to environmental and health issues, thus limiting their large-scale production applications. Free radicals have extremely high chemical reactivity and can also achieve CN cleavage efficiently under mild conditions. However, previous reports on free radical-induced CN bond cleavage have mainly focused on chain compounds. Due to the high energy barrier required for the dearomatization process, achieving CN bond cleavage in single heterocycles remains a huge challenge.

[0004] In recent years, research on energetic compounds based on nitrogen-containing heterocyclic skeletons has developed rapidly. However, traditional synthesis methods inevitably produce toxic substances that are harmful to humans and the environment. Therefore, seeking a simple and efficient method for synthesizing energetic heterocyclic skeletons that can be applied to actual production is a scientific problem that urgently needs to be tackled. Summary of the Invention

[0005] The object of the present invention is to provide an energetic compound 5,7-diamino-2,3,6-trinitropyrazolo[1,5-a]pyrimidine and a preparation method thereof.

[0006] An energetic compound I, named 5,7-diamino-2,3,6-trinitropyrazolo[1,5-a]pyrimidine, has the structural formula:

[0007]

[0008] An energetic compound II, named 2,5,7-triamino-3,6-dinitropyrazolo[1,5-a]pyrimidine, has the structural formula:

[0009]

[0010] The present invention also provides a method for synthesizing energetic compound II, comprising:

[0011] (1) a step of reacting 3,5-diamino-4-nitropyrazole (1) under the action of an oxidant to prepare a compound (E)-3-amino-3-((5-amino-4-nitro-1H-pyrazol-3-yl)amino)-2-nitropropene (2);

[0012]

[0013] (2) subjecting (E)-3-amino-3-((5-amino-4-nitro-1H-pyrazol-3-yl)amino)-2-nitropropene (2) to a ring-closure reaction in a hydrochloric acid solution to prepare an energetic compound II;

[0014]

[0015] Preferably, in step (1), the reaction is carried out in the presence of an organic solvent, which is any one of ethanol, methanol, acetonitrile and N,N-dimethylformamide; and the oxidant is any one of potassium periodate, tert-butyl hydroperoxide (tert-butyl peroxide), di-tert-butyl hydroperoxide, tert-butyl ammonium bromide, tert-butyl ammonium iodide, N-chlorosuccinimide, N-bromosuccinimide, N-iodosuccinimide and bromine water.

[0016] Preferably, in step (1), the reaction temperature is 0-40°C; and the reaction time is 30-120 minutes.

[0017] Preferably, in step (2), the mass fraction of the hydrochloric acid solution is 10% to 30%; the reaction temperature is 100 to 135° C., and the reaction time is 1 to 24 hours.

[0018] The present invention also provides a method for synthesizing energetic compound I, comprising:

[0019] The step of preparing the energetic compound I by subjecting the energetic compound II to oxidation reaction in an acidic system under the action of an oxidizing agent or a nitrating agent,

[0020]

[0021] Preferably, the oxidizing agent is 20% to 50wt% hydrogen peroxide, the nitrating agent is any one of fuming nitric acid and potassium nitrate; and the acid is any one of trifluoroacetic anhydride and concentrated sulfuric acid.

[0022] Preferably, the reaction temperature is 0-60°C and the reaction time is 3-24 hours.

[0023] The present invention also provides the use of the energetic compound II as a heat-resistant explosive.

[0024] The present invention also provides the use of the energetic compound I as a secondary explosive.

[0025] Compared with the prior art, the present invention has the following advantages: (1) The energetic compound 5,7-diamino-2,3,6-trinitropyrazolo[1,5-a]pyrimidine has high energy (detonation velocity: 8751 m s –1 ), low sensitivity (impact sensitivity: >60J, friction sensitivity: >240N), good thermal stability (thermal decomposition temperature: 265℃), etc., making it an energetic material with potential application value. (2) The raw materials for the preparation of this compound are easily available, and the synthetic route is simple and efficient. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a picture of an actual sample of 5,7-diamino-2,3,6-trinitropyrazolo[1,5-a]pyrimidine (I).

[0027] Figure 2 This is the H NMR spectrum of 5,7-diamino-2,3,6-trinitropyrazolo[1,5-a]pyrimidine (I).

[0028] Figure 3 This is the C NMR spectrum of 5,7-diamino-2,3,6-trinitropyrazolo[1,5-a]pyrimidine (I).

[0029] Figure 4 This is the DSC chart of 5,7-diamino-2,3,6-trinitropyrazolo[1,5-a]pyrimidine (I).

[0030] Figure 5 This is the H NMR spectrum of 2,5,7-triamino-3,6-dinitropyrazolo[1,5-a]pyrimidine(II).

[0031] Figure 6 This is the C NMR spectrum of 2,5,7-triamino-3,6-dinitropyrazolo[1,5-a]pyrimidine(II).

[0032] Figure 7 This is the DSC chart of 2,5,7-triamino-3,6-dinitropyrazolo[1,5-a]pyrimidine (II). DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0034] The present invention has the following synthetic route:

[0035] The specific steps are as follows:

[0036] (1) Synthesis of (E)-3-amino-3-((5-amino-4-nitro-1H-pyrazol-3-yl)amino)-2-nitropropene (2)

[0037] 3,5-Diamino-4-nitropyrazole (1) is dispersed in an organic solvent and stirred at 0-40°C. An oxidant is added to the solution and stirred for 30-120 minutes. The solution is then filtered, washed, and dried to obtain (E)-3-amino-3-((5-amino-4-nitro-1H-pyrazol-3-yl)amino)-2-nitropropene (referred to as compound 2). The organic solvent used is any one of ethanol, methanol, acetonitrile, and N,N-dimethylformamide, and the oxidant used is any one of potassium periodate, tert-butyl hydroperoxide (tert-butyl peroxide), di-tert-butyl hydroperoxide, tert-butyl ammonium bromide, tert-butyl ammonium iodide, N-chlorosuccinimide, N-bromosuccinimide, N-iodosuccinimide, and bromine water.

[0038] (2) Synthesis of compound 2,5,7-triamino-3,6-dinitropyrazolo[1,5-a]pyrimidine (3)

[0039] Compound 2 is dissolved in hydrochloric acid with a mass fraction of 10% to 30%; the reaction system temperature is then raised to 100 to 135°C and reacted for 1 to 24 hours. The reaction system is then cooled to room temperature, filtered, washed, and dried to obtain a solid product, 2,5,7-triamino-3,6-dinitropyrazolo[1,5-a]pyrimidine (referred to as compound 3).

[0040] (3) Synthesis of compound 5,7-diamino-2,3,6-trinitropyrazolo[1,5-a]pyrimidine (4)

[0041] Compound 3 is dissolved in an acid, wherein the acid used is either trifluoroacetic anhydride or concentrated sulfuric acid; then, a sufficient amount of an oxidizing agent or a nitrating agent is added to the solution in batches, wherein the oxidizing agent is 20% to 50% by mass of hydrogen peroxide, and the nitrating agent is either fuming nitric acid or potassium nitrate. After the addition, the system is heated to 0 to 60° C. and reacted for 3 to 24 hours. The reaction system is then cooled and poured into ice water, filtered, washed, and dried to obtain the target product 5,7-diamino-2,3,6-trinitropyrazolo[1,5-a]pyrimidine (referred to as target product 4).

[0042] Example 1

[0043] 1.14 g (8.0 mmol) of 3,5-diamino-4-nitropyrazole (prepared by reference to Solov'eva, NP; Makarov, VA; Granik, VG Highly Polarized Enamines 3. Study of the Spatial Structure of α,α-Diamino-β-cyano-β-nitroethylene Derivatives. Chem. Heterocycl. Compd. 1997, 33 (1), 78-85.) was dispersed in 10 mL of N,N-dimethylformamide and stirred. Then, N-bromosuccinimide (1.71 g, 9.6 mmol) was added to the solution. After the addition was completed, the mixture was stirred at 5°C for 30 minutes, filtered, washed, and dried to obtain compound 2 (yield: 72%, 0.73 g).

[0044] Compound 2 (0.76 g, 3.0 mmol) was dispersed in a 15% hydrochloric acid solution (20 mL), heated to 110°C, and heated for 2 hours. After heating, the reaction system was cooled, filtered, and dried to obtain compound 3 (yield: 75%, 0.57 g). Compound 3 (0.51 g, 2.0 mmol) was then added to 5 mL of concentrated sulfuric acid, and then a 30% hydrogen peroxide solution (3 mL) was slowly added dropwise to the reaction solution. The mixture was stirred at 10°C for 3 hours, and then the reaction solution was poured into ice water, filtered, washed, and dried to obtain the target product 4 (yield: 41%, 0.23 g), as shown in the following photo. Figure 1 shown.

[0045] Example 2

[0046] 1.14 g (8.0 mmol) of 3,5-diamino-4-nitropyrazole was dispersed in 10 mL of acetonitrile and stirred. Then, N-iodosuccinimide (2.16 g, 9.6 mmol) was added to the solution. After the addition was completed, the mixture was stirred at 15°C for 60 minutes, filtered, washed, and dried to obtain compound 2 (yield: 60%, 0.61 g).

[0047] Compound 2 (0.76 g, 3.0 mmol) was dispersed in a 20% hydrochloric acid solution (20 mL), heated to 115°C, and heated for 8 hours. After heating, the reaction system was cooled, filtered, and dried to obtain compound 3 (yield: 70%, 0.53 g). Compound 3 (0.51 g, 2.0 mmol) was then added to 5 mL of trifluoroacetic anhydride, and 50% hydrogen peroxide solution (3 mL) was slowly added dropwise to the reaction solution. The mixture was stirred at 20°C for 8 hours, and then the reaction solution was poured into ice water, filtered, washed, and dried to obtain the target product 4 (yield: 35%, 0.20 g).

[0048] Example 3

[0049] Disperse 1.14 g (8.0 mmol) of 3,5-diamino-4-nitropyrazole in 10 mL of ethanol and stir. Then, add bromine water (1.53 g, 9.6 mmol) to the solution. After the addition is complete, stir at 20°C for 90 minutes, filter, wash, and dry to obtain compound 2 (yield: 5%, 0.05 g).

[0050] Compound 2 (0.76 g, 3.0 mmol) was dispersed in 25% hydrochloric acid solution (20 mL), heated to 120°C, and heated for 12 hours. After heating, the reaction system was cooled, filtered, and dried to obtain compound 3 (yield: 68%, 0.52 g). Compound 3 (0.51 g, 2.0 mmol) was then added to 5 mL of concentrated sulfuric acid, and KNO3 (1.30 g, 10.0 mmol) was slowly added to the reaction solution. The mixture was stirred at 30°C for 12 hours, and then the reaction solution was poured into ice water, filtered, washed, and dried to obtain the target product 4 (yield: 74%, 0.42 g).

[0051] Example 4

[0052] Disperse 1.14 g (8.0 mmol) of 3,5-diamino-4-nitropyrazole in 5 mL of N,N-dimethylformamide and stir. Then, add bromine water (1.53 g, 9.6 mmol) to the solution. After the addition is complete, stir at room temperature for 120 minutes, filter, wash, and dry to obtain compound 2 (yield: 60%, 0.61 g).

[0053] Compound 2 (0.76 g, 3.0 mmol) was dispersed in a 30% hydrochloric acid solution (20 mL), heated to 125°C, and heated for 15 hours. After heating, the reaction system was cooled, filtered, and dried to obtain compound 3 (yield: 65%, 0.49 g). Compound 3 (0.51 g, 2.0 mmol) was then added to 5 mL of concentrated sulfuric acid, and fuming nitric acid (0.5 mL) was slowly added to the reaction solution. The mixture was stirred at 40°C for 15 hours, and then the reaction solution was poured into ice water, filtered, washed, and dried to obtain the target product 4 (yield: 72%, 0.41 g).

[0054] Example 5

[0055] Disperse 1.14 g (8.0 mmol) of 3,5-diamino-4-nitropyrazole in 5 mL of ethanol and stir. Then, add N-iodosuccinimide (2.16 g, 9.6 mmol) to the solution. After the addition is complete, stir at 30°C for 110 minutes, filter, wash, and dry to obtain compound 2 (yield: 10%, 0.10 g).

[0056] Compound 2 (0.76 g, 3.0 mmol) was dispersed in a 20% hydrochloric acid solution (15 mL), heated to 130°C, and heated for 18 hours. After heating, the reaction system was cooled, filtered, and dried to obtain compound 3 (yield: 66%, 0.50 g). Compound 3 (0.51 g, 2.0 mmol) was then added to 5 mL of concentrated sulfuric acid, and 50% hydrogen peroxide solution (3 mL) was slowly added dropwise to the reaction solution. The mixture was stirred at 50°C for 18 hours, and then the reaction solution was poured into ice water, filtered, washed, and dried to obtain the target product 4 (yield: 70%, 0.39 g).

[0057] Example 6

[0058] Disperse 1.14 g (8.0 mmol) of 3,5-diamino-4-nitropyrazole in 10 mL of methanol and stir. Then, add N-bromosuccinimide (1.71 g, 9.6 mmol) to the solution. After the addition is complete, stir at 35°C for 100 minutes, filter, wash, and dry to obtain compound 2 (yield: 8%, 0.08 g).

[0059] Compound 2 (0.76 g, 3.0 mmol) was dispersed in 18% hydrochloric acid solution (30 mL), heated to 135°C, and heated for 22 hours. After heating, the reaction system was cooled, filtered, and dried to obtain compound 3 (yield: 69%, 0.52 g). Compound 3 (0.51 g, 2.0 mmol) was then added to 10 mL of trifluoroacetic anhydride, and 30% hydrogen peroxide solution (5 mL) was slowly added dropwise to the reaction solution. The mixture was stirred at 60°C for 23 hours, and then the reaction solution was poured into ice water, filtered, washed, and dried to obtain the target product 4 (yield: 71%, 0.40 g).

[0060] The target product 4 obtained in Example 1 was subjected to spectral analysis, as shown in FIG. Figure 2 and Figure 3 As shown, the test results are as follows: 1 HNMR(DMSO-d6,500MHz)δ:9.96(s,1H),9.87(s,1H),9.20(s,1H),8.86(s,1H). 13 C NMR(DMSO-d6,125MHz)δ:156.3,153.3,147.6,143.5,109.4,109.2.IR(KBr,ν / cm –1):3625,3551,3391,3276,3151,1627,1501,1447,1393,1316,1240,1089,934,861,831,786,753,616. Elemental analysis: C6H4N8O6: Calculated (%): C 25.36, H 1.42, N 39.44. Found (%): C 25.43, H 1.44, N 39.51. This explosive crystal contains one molecule of methanol, with a density of 1.73 g cm –3 (4·CH3OH), thermal decomposition temperature is 265℃ (such as Figure 4 The theoretical detonation velocity is 8751 m s –1 With a detonation pressure of 32.5 GPa, it exhibits excellent detonation performance. Its impact sensitivity is >60J and its friction sensitivity is >240N. It can be used as a high explosive.

[0061] The compound 3 obtained in Example 1 was subjected to spectrum analysis, as shown in FIG. Figure 5 and Figure 6 As shown, the test results are as follows: 1 H NMR(DMSO-d6,500MHz)δ:9.35(s,1H),8.85(s,1H),8.62(s,1H),8.54(s,1H),6.84(s,2H). 13 CNMR(DMSO-d6,125MHz)δ:155.4,154.6,145.4,144.1,108.9,108.2.IR(KBr,ν / cm –1 ):3478,3425,3321,3278,3137,1618,1480,1373,1320,1227,1061,760,711,667,570,433. Elemental analysis: C6H6N8O4: Calculated (%): C 28.35, H 2.38, N 44.09. Found (%): C 28.46, H 2.44, N 44.21. The single crystal density of this explosive is 1.816 g cm –3 , thermal decomposition temperature is 364℃ (such as Figure 7 The theoretical detonation velocity is 8359 m s –1 , explosion pressure is 26.5GPa, impact sensitivity: >60J, friction sensitivity: >360N. It can be used as a heat-resistant explosive.

[0062] Although the present invention is described herein with reference to illustrative implementations of the present invention, the above embodiments are merely preferred embodiments of the present invention, and the implementation methods of the present invention are not limited to the above embodiments. It should be understood that those skilled in the art can design many other modifications and implementations, which will fall within the scope and spirit of the principles disclosed in this application.

Claims

1. An energetic compound II, characterized in that It is named 2,5,7-triamino-3,6-dinitropyrazolo[1,5-a]pyrimidine, and its structural formula is:

2. A method for synthesizing an energetic compound II, characterized in that: include: (1) a step of reacting 3,5-diamino-4-nitropyrazole (1) under the action of an oxidant to prepare a compound (E)-3-amino-3-((5-amino-4-nitro-1H-pyrazol-3-yl)amino)-2-nitropropene (2); (2) subjecting (E)-3-amino-3-((5-amino-4-nitro-1H-pyrazol-3-yl)amino)-2-nitropropene (2) to a ring-closure reaction in a hydrochloric acid solution to prepare an energetic compound II; Wherein, in step (1), the oxidant is any one of potassium periodate, tert-butyl hydroperoxide (tert-butyl peroxide), di-tert-butyl hydroperoxide, N-chlorosuccinimide, N-bromosuccinimide, N-iodosuccinimide and bromine water.

3. The method according to claim 2, wherein In step (1), the reaction is carried out in the presence of an organic solvent, which is any one of ethanol, methanol, acetonitrile and N,N-dimethylformamide.

4. The method according to claim 2, wherein In step (1), the reaction temperature is 0 to 40° C.; and the reaction time is 30 to 120 minutes.

5. The method according to claim 2, wherein In step (2), the mass fraction of the hydrochloric acid solution is 10% to 30%; the reaction temperature is 100 to 135° C., and the reaction time is 1 to 24 hours.

6. An energetic compound I, characterized in that It is named 5,7-diamino-2,3,6-trinitropyrazolo[1,5-a]pyrimidine, and its structural formula is:

7. A method for synthesizing an energetic compound I, characterized in that: include: The step of subjecting the energetic compound II as claimed in claim 1 to oxidation reaction in an acidic system under the action of an oxidizing agent or a nitrating agent to prepare the energetic compound I, 8. The method according to claim 7, wherein The oxidant is 20% to 50wt% hydrogen peroxide, the nitrating agent is any one of fuming nitric acid and potassium nitrate; the acid is any one of trifluoroacetic anhydride and concentrated sulfuric acid; the reaction temperature is 0 to 60 DEG C, and the reaction time is 3 to 24 hours.

9. Use of the energetic compound II as claimed in claim 1 as a heat-resistant explosive.

10. Use of the energetic compound I as claimed in claim 6 as a secondary explosive.

Images