A pyrazolopyrimidone single substance explosive and preparation method thereof

Abstract

The invention discloses a pyrazolopyrimidone single explosive and a preparation method thereof, and belongs to the technical field of single explosive synthesis. The pyrazolopyrimidone single explosive is N-(7-amino-3,6-dinitro-5-oxo-4,5-dihydropyrazole [1,5-a] pyrimidine-2-yl) ammonium nitrate, and its structure is as follows: This method uses easily available 3,5-diamino-4-nitropyrazole and ethyl cyanoacetate as raw materials, and can obtain the corresponding single explosive in two steps. The method not only has mild reaction conditions, strong operability, low cost, high safety, but also high reaction conversion rate and yield, short process flow, and easy expansion of reaction scale, and has the advantage of being suitable for industrial production.

Description

Technical Field

[0001] The invention relates to the field of single-substance explosives, in particular to a pyrazolopyrimidone single-substance explosive and a preparation method thereof. Background Art

[0002] Single-element explosives are important components of weapons, ammunition, pyrotechnics, etc. The energy of the explosives determines the destructive effect of the weapons. They are widely used in military, deep-sea drilling, airbags and civilian industries. Therefore, the research and development of new single-element explosives has received attention from countries around the world. Typical representatives of single-element explosives include TNT, RDX, HMX, hexanitrohexaazaisowurtzitane (CL-20), etc. Their energy levels gradually increase, but their ability to withstand external stimuli (heat, friction, impact, static electricity, etc.) decreases in turn. This is not conducive to the preparation, transportation, and storage of weapons and ammunition.

[0003] Nitrogen-rich heterocyclic rings are rich in NN and N=N bonds and have excellent energy properties. The products after their explosion are almost all nitrogen, which is more environmentally friendly than traditional explosives. Among them, nitrogen-rich fused rings have become a hot topic in the study of single-substance explosives because they have a larger conjugated area, more NN and N=N bonds, and more sites for introducing energetic groups. The explosive groups in single-substance explosives include nitro, ammonium nitrate, geminal dinitromethyl, trinitromethyl, azide, etc. Their introduction can quickly increase the energy, but will make the sensitivity of the compound worse.

[0004] In recent years, Professor Shreeve's research group at the University of Idaho has developed several single explosives containing carbonyl groups. The introduction of carbonyl groups can significantly increase the density and oxygen content of the compound, and its sensitivity is good. For example, the density of 3,5-diamino-6-hydroxy-2-coordinated oxygen-4-nitropyrimidone (I) is as high as 1.95 g.cm -3 , the detonation speed is 8660 ms -1 , and its impact sensitivity and friction sensitivity meet the standards of insensitive explosives (JACS, 2021, 143, 12665-12674); the density and thermal decomposition temperature of di(3-nitro-1-(trinitromethyl)-1H-1,2,4-triazol-5-yl)methanone (II) are higher than those of the corresponding carbonyl-free compounds.

[0005]

[0006] In summary, although several carbonyl-containing single-element explosives have been synthesized, there are almost no reports on carbonyl-containing condensed-ring single-element explosives. Considering that condensed rings have large conjugated areas and abundant high-energy bonds, the introduction of carbonyl groups can increase the energy and density of compounds and improve their tolerance to external stimuli. Therefore, the development of carbonyl-containing condensed-ring single-element explosives is of great research significance and has important application potential in military and civilian fields. Summary of the invention

[0007] In view of the fact that there are few carbonyl-based single-substance explosive compounds at present, especially the research on carbonyl-containing fused-ring single-substance explosives has not made a major breakthrough, the purpose of the present invention is to provide a pyrazolopyrimidone single-substance explosive, which is a pyrazolopyrimidone single-substance explosive with a high density (ƿ=2.01 g cm -3 ), good thermal stability (thermal decomposition temperature is 104℃), insensitive to external stimuli (IS>40J, FS>360N), excellent calculated detonation performance (Dv = 9014 ms -1 , P = 35.4 MPa) of single explosive.

[0008] Another inventive object of the present application is to provide a method for preparing the above-mentioned pyrazolopyrimidone single-substance explosive, which has mild reaction conditions, strong operability, low cost, high safety, high reaction conversion rate and yield, short process flow, and easy expansion of reaction scale.

[0009] In order to achieve the above invention objectives, the specific technical solutions adopted by the present invention are as follows:

[0010] A pyrazolopyrimidinone single explosive, whose chemical name is (7-amino-3,6-dinitro-5-oxo-4,5-dihydropyrazolo[1,5-a]pyrimidin-2-yl)ammonium nitrate, and whose structure is shown below:

[0011] .

[0012] A method for preparing a pyrazolopyrimidone single-substance explosive comprises the following steps:

[0013] 3,5-diamino-4-nitropyrazole and ethyl cyanoacetate are used as raw materials, triethylamine is used as a base, the three are dissolved in a polar solvent and stirred fully, and the temperature is raised for a period of time to reach the reaction end point, and then 2,7-diamino-3-nitropyrazol[1,5-a]pyrimidin-5(4H)-one is obtained through separation and purification. 2,7-diamino-3-nitropyrazol[1,5-a]pyrimidin-5(4H)-one is nitrated by using a nitration system to obtain N-(7-amino-3,6-dinitro-5-oxo-4,5-dihydropyrazol[1,5-a]pyrimidin-2-yl)ammonium nitrate.

[0014] As a preferred embodiment of the present application, the polar solvent refers to any one of ethanol, acetonitrile, dimethyl sulfoxide, N,N-dimethylformamide, or a combination thereof.

[0015] As a preferred embodiment of the present application, the mass ratio of 3,5-diamino-4-nitropyrazole, ethyl cyanoacetate and triethylamine is (1: 1~5: 1~5).

[0016] As a preferred embodiment of the present application, the reaction temperature in the temperature-raising reaction is 50-150°C.

[0017] As a better implementation method in the present application, the reaction endpoint is determined by detecting the complete conversion of the 3,5-diamino-4-nitropyrazole raw material in the reaction solution by thin layer chromatography, the thin layer chromatography silica gel is silica gel GF254, and the thin layer chromatography developing solvent is a solution of petroleum ether and ethyl acetate in a volume ratio of 1 to 50:1; the color development method is iodine color development or ultraviolet color development.

[0018] As a better embodiment of the present application, the specific steps of separation and purification are as follows: after the reaction reaches the end point, the reaction bottle is cooled to room temperature, and the solid is directly filtered and separated to obtain 2,7-diamino-3-nitropyrazolo[1,5-a]pyrimidin-5(4H)-one. After the nitration reaction is completed, the reaction solution is directly poured into ice water, and the precipitated solid is directly filtered to obtain N-(7-amino-3,6-dinitro-5-oxo-4,5-dihydropyrazolo[1,5-a]pyrimidin-2-yl)ammonium nitrate single explosive.

[0019] As a better embodiment of the present application, the nitration system refers to any one of pure nitric acid, nitric-sulfuric acid mixed acid (nitric acid: sulfuric acid volume ratio of 1:3), nitric acid-acetic anhydride (volume ratio of 1:3) or nitric acid-trifluoroacetic anhydride (volume ratio of 1:3); the temperature of the nitration reaction is -5~100°C.

[0020] As a better embodiment of the present application, the N-(7-amino-3,6-dinitro-5-oxo-4,5-dihydropyrazolo[1,5-a]pyrimidin-2-yl)ammonium nitrate prepared by the above method is a high density (ƿ=2.01 g cm -3 ), good thermal stability (thermal decomposition temperature is 104℃), insensitive to external stimuli (IS>40J, FS>360N), excellent calculated detonation performance (Dv = 9014 ms -1 , P = 35.4 MPa) of single explosive.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] (i) Using easily available 3,5-diamino-4-nitropyrazole as a raw material, N-(7-amino-3,6-dinitro-5-oxo-4,5-dihydropyrazolo[1,5-a]pyrimidin-2-yl)ammonium nitrate single explosive can be obtained through two-step reaction, and the operation is simple.

[0023] (ii) The reaction conditions are mild, the operability is strong, the cost is low, the safety is high, the reaction conversion rate and yield are high, the process flow is short, and the reaction scale is easy to expand.

[0024] (III) The product is a high-energy, low-sensitivity carbonyl nitrogen-rich fused ring energetic material, which is easy to separate and has the advantage of being suitable for industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 2,7-diamino-3-nitropyrazolo[1,5-a]pyrimidin-5(4H)-one obtained in Example 1 1 H NMR spectrum.

[0026] Figure 2 2,7-diamino-3-nitropyrazolo[1,5-a]pyrimidin-5(4H)-one obtained in Example 1 13 CNMR spectrum.

[0027] Figure 3 The N-(7-amino-3,6-dinitro-5-oxo-4,5-dihydropyrazolo[1,5-a]pyrimidin-2-yl)ammonium nitrate obtained in Example 2 1 H NMR spectrum.

[0028] Figure 4 The N-(7-amino-3,6-dinitro-5-oxo-4,5-dihydropyrazolo[1,5-a]pyrimidin-2-yl)ammonium nitrate obtained in Example 2 13 CNMR spectrum.

[0029] Figure 5 This is the single crystal diffraction pattern of N-(7-amino-3,6-dinitro-5-oxo-4,5-dihydropyrazolo[1,5-a]pyrimidin-2-yl)ammonium nitrate obtained in Example 2. DETAILED DESCRIPTION

[0030] A pyrazolopyrimidinone single explosive, whose chemical name is (7-amino-3,6-dinitro-5-oxo-4,5-dihydropyrazolo[1,5-a]pyrimidin-2-yl)ammonium nitrate, and whose structure is shown below:

[0031] .

[0032] A method for preparing a pyrazolopyrimidone single-substance explosive comprises the following steps:

[0033] 3,5-diamino-4-nitropyrazole and ethyl cyanoacetate are used as raw materials, triethylamine is used as a base, the three are dissolved in a polar solvent and stirred fully, and the temperature is raised for a period of time to reach the reaction end point, and then 2,7-diamino-3-nitropyrazol[1,5-a]pyrimidin-5(4H)-one is obtained through separation and purification. 2,7-diamino-3-nitropyrazol[1,5-a]pyrimidin-5(4H)-one is nitrated by using a nitration system to obtain N-(7-amino-3,6-dinitro-5-oxo-4,5-dihydropyrazol[1,5-a]pyrimidin-2-yl)ammonium nitrate.

[0034] Preferably, the polar solvent is any one of ethanol, acetonitrile, dimethyl sulfoxide, N,N-dimethylformamide, or a combination thereof.

[0035] Preferably, the mass ratio of 3,5-diamino-4-nitropyrazole, ethyl cyanoacetate and triethylamine is (1:1~5:1~5), that is, it can be specifically selected as 1:1:1, 1:2:2, 1:3:3, (1:4:4, 1:5:5, 1:1:2, 1:1:3, 1:1:4, 1:1:5, 1:2:1, 1:2:3, 1:2:4, 1:2:5, 1:3:1, 1:3:2, 1:3:3, 1:3:4, 1:3:5, 1:4:1, 1:4:2, 1:4:3, 1:4:4, 1:4:5 and the like.

[0036] Preferably, the reaction temperature in the temperature-elevated reaction is 50-150°C, specifically 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C and the like.

[0037] Preferably, the reaction endpoint is determined by detecting the complete conversion of 3,5-diamino-4-nitropyrazole in the reaction solution by thin layer chromatography, the thin layer chromatography silica gel is silica gel GF254, the thin layer chromatography developing solvent is a solution of petroleum ether and ethyl acetate in a volume ratio of 1 to 50:1; the color development method is iodine color development or ultraviolet color development.

[0038] Preferably, the specific steps of separation and purification are as follows: after the reaction reaches the end point, the reaction bottle is cooled to room temperature, and the solid is directly filtered and separated to obtain 2,7-diamino-3-nitropyrazolo[1,5-a]pyrimidin-5(4H)-one. After the nitration reaction is completed, the reaction solution is directly poured into ice water, and the precipitated solid is directly filtered to obtain N-(7-amino-3,6-dinitro-5-oxo-4,5-dihydropyrazolo[1,5-a]pyrimidin-2-yl)ammonium nitrate single explosive.

[0039] Preferably, the nitration system refers to any one of pure nitric acid, nitric-sulfuric acid mixed acid (nitric acid:sulfuric acid volume ratio 1:3), nitric acid-acetic anhydride (volume ratio 1:3) or nitric acid-trifluoroacetic anhydride (volume ratio 1:3); the temperature of the nitration reaction is -5~100°C.

[0040] Preferably, the N-(7-amino-3,6-dinitro-5-oxo-4,5-dihydropyrazolo[1,5-a]pyrimidin-2-yl)ammonium nitrate prepared by the above method is a high density (ƿ=2.01 g cm -3 ), good thermal stability (thermal decomposition temperature is 104℃), insensitive to external stimuli (IS>40J, FS>360N), excellent calculated detonation performance (Dv = 9014 ms -1 , P =35.4 MPa) of single explosive.

[0041] The following describes the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict.

[0042] It should be noted that, in order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0043] Therefore, the following detailed description of the embodiments of the present invention is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0044] 3,5-Diamino-4-nitropyrazole is a known compound and can be synthesized using existing techniques.

[0045] Polar solvents are cheap and readily available. As reaction solvents, they help dissolve the reactant substrates and orderly promote the nucleophilic substitution reaction or cyclization reaction, effectively avoiding side reactions and improving the reaction yield. Ethanol is a commonly used proton polar solvent, so anhydrous ethanol is used as the reaction solvent in this embodiment.

[0046] Example 1 Preparation of Compound 2,7-diamino-3-nitropyrazolo[1,5-a]pyrimidin-5(4H)-one:

[0047]

[0048] Compound 1 (2.86 g, 20 mmol) and 40 mL of ethanol solvent were added to a 250 mL dry three-necked flask equipped with a magnetic stirrer, and compound 2 (4.52 g, 40 mmol) and triethylamine (2.02 g, 20 mmol) were added under stirring. The reaction flask was then placed in an oil bath at 100°C and stirred for 8 h. After confirming the reaction endpoint by thin layer chromatography, the reaction flask was cooled to room temperature, the precipitated solid was filtered, and washed with a small amount of ether to obtain 3.53 g of a green solid (3) with a yield of 84%.

[0049] 1 H NMR (600 MHz, DMSO) δ 11.64 (s, 1H), 7.41 (s, 2H), 6.66 (s, 2H), 5.34 (s, 1H). 13 C NMR (151 MHz, DMSO) δ 153.37, 149.53, 142.71, 108.59, 100.00,78.69. IR(KBr)max 3332,3214,2918,1670,1456, 1388,1278,1120, 933,762, 655cm -1 ; elemental analysis (%) for C6H6N6O3 (210.0):calcd C 34.29; H 2.88; N 39.99. Found: C 34.32; H 2.95; N 40.55.

[0050] Example 2 Preparation of the compound N-(7-amino-3,6-dinitro-5-oxo-4,5-dihydropyrazolo[1,5-a]pyrimidin-2-yl)ammonium nitrate:

[0051]

[0052] 30 mL of acetic anhydride was added to a dry reaction bottle, and the reaction bottle was cooled to 0°C in a low temperature tank. 10 mL of pure nitric acid was added dropwise, and then the compound 3 (2.1 g, 10 mmol) prepared in Example 1 was slowly added. After reacting for 3 hours, the reaction solution was poured into ice water and filtered to obtain a solid product 4 with a yield of 51%.

[0053] Example 3 Preparation of the compound N-(7-amino-3,6-dinitro-5-oxo-4,5-dihydropyrazolo[1,5-a]pyrimidin-2-yl)ammonium nitrate:

[0054]

[0055] 30 mL of trifluoroacetic anhydride was added to a dry reaction bottle, and the reaction bottle was cooled to 0°C in a low temperature tank. 10 mL of pure nitric acid was added dropwise thereto, and then the compound 3 (2.1 g, 10 mmol) prepared in Example 1 was slowly added. After reacting for 3 hours, the reaction solution was poured into ice water and filtered to obtain a solid product 4 with a yield of 48%.

[0056] Example 4 Preparation of the compound N-(7-amino-3,6-dinitro-5-oxo-4,5-dihydropyrazolo[1,5-a]pyrimidin-2-yl)ammonium nitrate:

[0057]

[0058] 30 mL of concentrated sulfuric acid was added to a dry reaction bottle, and the reaction bottle was cooled to 30°C in a low temperature tank. 10 mL of pure nitric acid was added dropwise, and then compound 3 (2.1 g, 10 mmol) prepared in Example 1 was slowly added. After reacting for 3 hours, the reaction solution was poured into ice water and filtered to obtain a solid product 4 with a yield of 82%.

[0059] The thermal decomposition temperature of compound 4 was tested by differential scanning calorimetry (DSC), which showed that the thermal decomposition temperature of the compound was 104.5°C. The density of the compound was measured by density meter (2.01 g.cm -3 ), the impact sensitivity and friction sensitivity of the compound were measured by the impact sensitivity meter and the friction sensitivity meter, which were >40J and >360N respectively. After the formation enthalpy of the compound was obtained by Gaussian calculation, the theoretical detonation performance of the compound was calculated in combination with the density (Dv = 9014 ms -1 , P = 35.4MPa).

[0060] 1 H NMR (600 MHz, DMSO) δ 9.60 (s, 2H), 5.41 (s, 2H). 13 C NMR (151 MHz, DMSO) δ 154.09, 148.98, 142.89, 140.27, 112.56, 112.21. IR(KBr)max 3341,3232, 2944, 1652, 1433, 1267, 1132, 946,733, 627cm-1 ; elemental analysis (%) for C6H4N8O7 (300.0): calcd C 24.01; H 1.34; N 37.33. Found: C 23.98; H 1.42; N38.20.

[0061] The above-mentioned examples are only preferred implementations of this patent, but the protection scope of this patent is not limited thereto. It should be pointed out that, for ordinary technicians in this technical field, without departing from the principle of this patent, according to the technical solution and patent concept of this patent, several improvements and modifications can be made, and these improvements and modifications should also be regarded as the protection scope of this patent.

Claims

1. A pyrazolopyrimidone single explosive, characterized in that The pyrazolopyrimidinone single explosive is N-(7-amino-3,6-dinitro-5-oxo-4,5-dihydropyrazolo[1,5-a]pyrimidin-2-yl)ammonium nitrate, and its structure is as follows: 。 2. The method for preparing the pyrazolopyrimidone explosive according to claim 1, characterized in that The steps include: 3,5-diamino-4-nitropyrazole and ethyl cyanoacetate are used as raw materials, triethylamine is used as a base, the three are dissolved in a polar solvent in proportion, and then stirred fully. After the temperature is raised for a period of time to reach the reaction end point, 2,7-diamino-3-nitropyrazol[1,5-a]pyrimidin-5(4H)-one is obtained through separation and purification; 2,7-diamino-3-nitropyrazol[1,5-a]pyrimidin-5(4H)-one is subjected to nitration reaction using a nitration system to obtain N-(7-amino-3,6-dinitro-5-oxo-4,5-dihydropyrazol[1,5-a]pyrimidin-2-yl)ammonium nitrate; the nitration system is any one of pure nitric acid, nitric and sulfuric acid mixed acid, nitric acid-acetic anhydride or nitric acid-trifluoroacetic anhydride; and the temperature of the nitration reaction is -5 to 100°C.

3. The method for preparing the pyrazolopyrimidone single substance explosive according to claim 2, characterized in that: The polar solvent is any one of ethanol, acetonitrile, dimethyl sulfoxide or N,N-dimethylformamide or a mixture of several of them.

4. The method for preparing the pyrazolopyrimidone single substance explosive according to claim 2, characterized in that: The mass ratio of 3,5-diamino-4-nitropyrazole, ethyl cyanoacetate and triethylamine is 1: 1~5: 1~5.

5. The method for preparing the pyrazolopyrimidone single substance explosive according to claim 2, characterized in that: The temperature of the heating reaction is 50-150° C. The reaction endpoint is determined by detecting the complete conversion of the 3,5-diamino-4-nitropyrazole raw material in the reaction solution by thin layer chromatography. The thin layer chromatography silica gel is silica gel GF254, and the thin layer chromatography developing solvent is a petroleum ether and ethyl acetate solution in a volume ratio of 1 to 50:1; the color development method is iodine color development or ultraviolet color development.

6. The method for preparing the pyrazolopyrimidone single substance explosive according to claim 2, characterized in that: The specific steps of separation and purification are as follows: after the reaction reaches the end point, the reaction bottle is cooled to room temperature, and the solid is directly filtered and separated to obtain 2,7-diamino-3-nitropyrazolo[1,5-a]pyrimidin-5(4H)-one.

7. The method for preparing the pyrazolopyrimidone single substance explosive according to claim 2, characterized in that: After the nitration reaction is completed, the reaction solution is directly poured into ice water, and the precipitated solid is directly filtered to obtain N-(7-amino-3,6-dinitro-5-oxo-4,5-dihydropyrazolo[1,5-a]pyrimidin-2-yl)ammonium nitrate single explosive.

Images