6-nitro-7-amino-[1,2,4]triazole[1,5-a]pyrimidine, synthesis method and application thereof

Abstract

The present invention provides a 6-nitro-7-amino-[1,2,4]triazole[1,5-a]pyrimidine, a synthesis method and an application thereof, wherein the structure thereof is as follows: As a compound synthesized for the first time, the compound of the present invention is used as a single explosive, and has excellent detonation performance and heat resistance. The sensitivity of the compound of the present invention is relatively low: the friction sensitivity (FS) is greater than 360N, and the impact sensitivity (IS) is greater than 40J.

Description

Technical Field

[0001] The invention belongs to the technical field of energetic materials, relates to single-substance explosives, and specifically relates to 6-nitro-7-amino-[1,2,4]triazole[1,5-a]pyrimidine, a synthesis method and application thereof. Background Art

[0002] Energetic materials are the power source and force source of weapon systems. The diversity, complexity, and uncertainty of future war modes and combat environments put forward more stringent and special requirements for the battlefield adaptability of new weapon systems. In recent years, with the increasingly harsh environment in which weapons and ammunition are used, safety accidents in arsenals around the world have occurred frequently. As an important role in improving the survivability of weapon systems on the battlefield, insensitive explosives have become a focus of industry research. The demand for new high-energy insensitive materials (detonation velocity>8000m / s, impact sensitivity>15J) is becoming more and more urgent. However, for energetic compound molecules, there is an inherent contradiction between energy and sensitivity: energetic compound molecules usually need to introduce more explosive groups (such as nitro) to increase the formation enthalpy and oxygen balance value, and this strong electron-withdrawing group will cause charge separation within the molecule. The higher the degree of charge separation, the weaker the C-NO2 / N-NO2 bond in the molecule, and the more unstable the molecule. Summary of the invention

[0003] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a 6-nitro-7-amino-[1,2,4]triazole[1,5-a]pyrimidine, a synthesis method and an application thereof, so as to solve the technical problem that the heat resistance and insensitivity of energetic organic small molecule single substance explosives in the prior art need to be further improved.

[0004] In order to solve the above technical problems, the present invention adopts the following technical solutions to achieve the above problems:

[0005] A 6-nitro-7-amino-[1,2,4]triazolo[1,5-a]pyrimidine, the structure of which is shown below:

[0006]

[0007] The present invention also protects a first method for synthesizing 6-nitro-7-amino-[1,2,4]triazolo[1,5-a]pyrimidine as described above, which comprises the following steps:

[0008] In an ice-water bath at 0°C, add fuming HNO3 and concentrated H2SO4, and add 7-amino-[1,2,4]triazole[1,5-a]pyrimidine under stirring. After the addition, the reaction solution is gradually heated to 80°C and maintained for 4.0 hours, then cooled to room temperature, ice is poured into the reaction solution, and the pH is adjusted to 7, and a white solid precipitates; the white solid is obtained by suction filtration, washed, and dried to obtain a white solid product, namely 6-nitro-7-amino-[1,2,4]triazole[1,5-a]pyrimidine.

[0009] The present invention also protects a second method for synthesizing 6-nitro-7-amino-[1,2,4]triazolo[1,5-a]pyrimidine as described above, which method comprises the following steps:

[0010] In an ice-water bath at 0°C, add concentrated H2SO4, add 7-amino-[1,2,4]triazole[1,5-a]pyrimidine under stirring, then add KNO3 to the reaction solution, gradually heat the reaction solution to 140°C, pour the reaction solution into crushed ice after the reaction is completed, and a white solid precipitates; filter to obtain a white solid product, which is 6-nitro-7-amino-[1,2,4]triazole[1,5-a]pyrimidine.

[0011] The present invention also protects a third method for synthesizing 6-nitro-7-amino-[1,2,4]triazolo[1,5-a]pyrimidine as described above, which method comprises the following steps:

[0012] In an ice-water bath at 0°C, add 10.0 mL of concentrated HNO3, and then add 7-amino-[1,2,4]triazole[1,5-a]pyrimidine under stirring. Then the reaction solution is gradually heated to 25°C, and the reaction solution is stirred at 25°C for 4.0 h. Finally, the reaction solution is gradually heated to 115°C. After the reaction is completed, the reaction solution is poured into crushed ice, and a white solid precipitates. The white solid product is obtained by suction filtration, which is 6-nitro-7-amino-[1,2,4]triazole[1,5-a]pyrimidine.

[0013] The present invention also protects the use of 6-nitro-7-amino-[1,2,4]triazolo[1,5-a]pyrimidine as a single explosive.

[0014] The present invention also protects the use of 6-nitro-7-amino-[1,2,4]triazole[1,5-a]pyrimidine synthesized by the above-mentioned synthesis method of 6-nitro-7-amino-[1,2,4]triazole[1,5-a]pyrimidine as a single explosive.

[0015] Compared with the prior art, the present invention has the following technical effects:

[0016] (I) The 6-nitro-7-amino-[1,2,4]triazolo[1,5-a]pyrimidine compound of the present invention has excellent detonation performance and heat resistance.

[0017] (II) The sensitivity of the 6-nitro-7-amino-[1,2,4]triazolo[1,5-a]pyrimidine compound of the present invention is relatively low: friction sensitivity (FS)>360N, impact sensitivity (IS)>40J.

[0018] (III) The raw materials for the synthesis method of the present invention are cheap and readily available: 7-amino-[1,2,4]triazolo[1,5-a]pyrimidine, fuming HNO3, concentrated H2SO4, KNO3 and concentrated HNO3 are all commercial reagents.

[0019] (IV) The synthesis method of the present invention is simple, the synthesis conditions are very mild, and the yield is high. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is the single crystal structure diagram of 6-nitro-7-amino-[1,2,4]triazolo[1,5-a]pyrimidine.

[0021] The specific contents of the present invention are further explained in detail below in conjunction with embodiments. DETAILED DESCRIPTION

[0022] It should be noted that, unless otherwise specified, all raw materials in the present invention are raw materials known in the prior art.

[0023] The design, synthesis and application of a large number of nitrogen heteroaromatic energetic compounds as high-energy explosives and propellant formulation components have been widely reported. Among them, triazolopyrimidine nitrogen-rich heterocyclic compounds are undoubtedly the most eye-catching "star" molecules in recent years, because their molecular structures contain a large number of NN, CN, N=N, C=N bonds, have high formation enthalpy and nitrogen content, can produce high energy when decomposed, release a large amount of nitrogen, have low carbon and hydrogen content, low characteristic signals, are environmentally friendly, and easy to achieve oxygen balance. In addition, the entire molecular structure of triazolopyrimidine nitrogen-rich heterocyclic compounds can form a large π bond system similar to the benzene ring structure, which can effectively reduce the degree of molecular charge separation caused by the explosive group, and is one of the most effective ways to obtain high-energy insensitive energetic compounds. In addition, triazolopyrimidine nitrogen-rich heterocyclic compounds have made great research progress in the field of civilian medicines, but there are few reports on research in the field of energetic materials. Therefore, introducing triazolopyrimidine nitrogen-rich heterocyclic structures into the field of energetic materials has extremely high military value.

[0024] The concept of the present invention is:

[0025] Recently, nitrogen heteroaromatic compounds have become a hot topic in the field of energetic materials research and development. Such compounds can often form a conjugated delocalized system with a benzene-like structure. They are a type of single-substance energetic material with low impact and friction sensitivity, high thermal decomposition temperature, and good detonation performance. Among them, energetic materials containing triazole pyrimidine structures have attracted great attention from scientists from all over the world. For the selection of designed C, H, O, and N high energy density compounds, the triazole pyrimidine ring is a very effective structural unit. The triazole pyrimidine ring has the following advantages:

[0026] ① The pyrimidine ring is a planar structure, and the six electrons on the ring form a conjugated large π bond, which has a certain aromaticity. The triazole ring is a "potential nitro" inner ring structure, containing 3 nitrogen atoms in one ring, and the nitrogen content and molecular crystal density are higher. The energetic derivatives of triazole pyrimidine ring have become one of the research directions that have attracted much attention in the field of energetic materials research due to their advantages such as high energy density, high standard formation enthalpy, and high nitrogen content. ② The nitrogen-containing fused ring structure of triazole pyrimidine is compact and has a near-planar structure that is conducive to molecular stacking. On the one hand, it makes it have a higher density, and on the other hand, it effectively improves the energy level of energetic compounds, thereby having better detonation performance. ③ At the same time, the delocalized π electrons significantly improve the stability of the fused ring skeleton. Therefore, the aromaticity of the fused ring of triazole pyrimidine increases the thermal decomposition temperature of the compound by improving the stability of the fused ring skeleton. ④ The aromaticity makes the atoms in the fused ring as much as possible in the same plane, and reduces the torsion angle between the exocyclic nitro group, amino group and the parent ring through the conjugation effect, thereby making triazole pyrimidine have a quasi-planar structure, which is conducive to the close stacking of molecules to increase density and reduce sensitivity. In addition, since the electronegativity of nitrogen and oxygen atoms in such high-nitrogen compound molecules is high and most of them have unused lone electron pairs, the entire heterocyclic system easily forms a large π-bond conjugated structure similar to a benzene ring. Therefore, it has the advantages of good thermal stability and insensitivity to friction and impact stimulation. Moreover, triazole pyrimidine nitrogen-rich heterocyclic compounds have made great research progress in the field of civilian medicines, but there are few reports on research in the field of energetic materials. Therefore, introducing triazole pyrimidine nitrogen-rich heterocyclic structures into the field of energetic materials has extremely high military value.

[0027] Based on this, the present invention designs a 6-nitro-7-amino-[1,2,4]triazole[1,5-a]pyrimidine compound with a high-energy group based on the structure of the molecular skeleton of the triazole pyrimidine nitrogen-fused ring structure, and uses quantum chemical density functional theory to study the influence of the parent structure and energetic groups on the compound structure and detonation performance (formation enthalpy, detonation pressure), hoping to obtain a molecular structure of an energetic compound with excellent performance, and at the same time, provide a theoretical basis for subsequent related research work.

[0028] The 6-nitro-7-amino-[1,2,4]triazolo[1,5-a]pyrimidine of the present invention is synthesized for the first time, and its structure is shown below:

[0029]

[0030] Specific embodiments of the present invention are given below. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent changes made on the basis of the technical solution of this application fall within the protection scope of the present invention.

[0031] Embodiment 1:

[0032] This embodiment provides a method for synthesizing 6-nitro-7-amino-[1,2,4]triazolo[1,5-a]pyrimidine, which comprises the following steps:

[0033]

[0034] Under 0℃ ice-water bath conditions, add 1.25mL fuming HNO3 (mass concentration of 96%) and 9.60mL concentrated H2SO4 (mass concentration of 98%) to a 50mL three-necked flask, add 1.35g (10mmol) 7-amino-[1,2,4]triazole[1,5-a]pyrimidine under stirring, after adding, gradually heat the reaction solution to 80℃ and keep it for 4.0h, then cool to room temperature, pour 30.0g ice into the reaction solution, adjust the pH to 7 with ammonia water, and a white solid precipitates. Filter to obtain a white solid, and wash it repeatedly with 15mL of distilled water 3 times. Dry the obtained white solid. Obtain a white solid product with a yield of 87%.

[0035] Structure identification:

[0036] ①Infrared spectrum test:

[0037] Infrared spectrum (KBr, cm -1 ): 3418 (-NH stretching vibration), 3206 (-CH stretching vibration), 1509 (ON stretching vibration), 1363 (ON stretching vibration), 1196 (CN symmetric stretching vibration), 736 (-NH out-of-plane deformation vibration).

[0038] ②NMR 1 H NMR and 13 C NMR:

[0039] 1 H NMR(DMSO-d6,400MHz): δ8.70(s,1H),9.36(s,1H),9.48(br s,2H).

[0040] 13 C NMR (DMSO-d6,101MHz): δ119.1,145.8,151.9,156.0,156.4.

[0041] ③Elemental analysis:

[0042] Anal.calcd for C5H4N6O2:C,33.34;H,2.24;N,46.66.

[0043] Found:C,33.24;H,2.06;N,46.53.

[0044] ④Single crystal structure test:

[0045] The single crystal structure is shown in Figure 1 shown.

[0046] The above data confirm that the product obtained from the above reaction is a 6-nitro-7-amino-[1,2,4]triazolo[1,5-a]pyrimidine compound.

[0047] Embodiment 2:

[0048] This embodiment provides a method for synthesizing 6-nitro-7-amino-[1,2,4]triazolo[1,5-a]pyrimidine, which comprises the following steps:

[0049]

[0050] Under 0℃ ice-water bath conditions, add 13.3mL concentrated H2SO4 (mass concentration of 98%) to a 50mL three-necked flask, add 1.35g (10mmol) 7-amino-[1,2,4]triazole[1,5-a]pyrimidine under stirring, then add 1.0g KNO3 to the reaction solution, and gradually heat the reaction solution to 140℃. After the reaction is completed, pour the reaction solution into 30.0g crushed ice, and a white solid precipitates. Filter and obtain a white solid product with a yield of 81%.

[0051] The structural identification results of this example are the same as those of Example 1.

[0052] The thermal performance test results of this embodiment are the same as those of embodiment 1.

[0053] Embodiment 3:

[0054] This embodiment provides a method for synthesizing 6-nitro-7-amino-[1,2,4]triazolo[1,5-a]pyrimidine, which comprises the following steps:

[0055]

[0056] Under 0℃ ice-water bath conditions, add 10.0mL concentrated HNO3 (mass concentration of 68%) to a 50mL three-necked flask, add 1.35g (10mmol) 7-amino-[1,2,4]triazole[1,5-a]pyrimidine under stirring, then gradually heat the reaction solution to 25℃, stir the reaction solution at 25℃ for 4.0h, and finally gradually heat the reaction solution to 115℃. After the reaction is completed, pour the reaction solution into 30.0g crushed ice, a white solid precipitates, and filter to obtain a white solid product with a yield of 78%.

[0057] The structural identification results of this example are the same as those of Example 1.

[0058] The thermal performance test results of this embodiment are the same as those of embodiment 1.

[0059] Embodiment 4:

[0060] This example shows the use of 6-nitro-7-amino-[1,2,4]triazolo[1,5-a]pyrimidine as a single explosive.

[0061] The 6-nitro-7-amino-[1,2,4]triazole[1,5-a]pyrimidine is the 6-nitro-7-amino-[1,2,4]triazole[1,5-a]pyrimidine synthesized in the above-mentioned Example 1, Example 2 or Example 3.

[0062] Thermal performance test:

[0063] The thermal properties were tested by DSC (differential scanning calorimetry) in a nitrogen environment at a heating rate of 10°C / min, and the decomposition temperature of the 6-nitro-7-amino-[1,2,4]triazole[1,5-a]pyrimidine compound was 350°C.

[0064] Sensitivity performance test:

[0065] According to GJB772A-97 method, the impact explosion probability P was measured by using WL-1 explosive impact sensitivity meter and WM-1 explosive friction sensitivity meter. I (10kg drop weight, 25cm drop height), characteristic drop height H 50 (5kg drop weight) and friction explosion probability P F (3.92MPa gauge pressure, 90° swing angle).

[0066] After testing: the impact sensitivity (IS) of 6-nitro-7-amino-[1,2,4]triazole[1,5-a]pyrimidine compound is greater than 40J, and the friction sensitivity (FS) is greater than 360N.

[0067] Detonation performance test:

[0068] In order to study the detonation performance of synthesized 6-nitro-7-amino-[1,2,4]triazole[1,5-a]pyrimidine compound derivatives, the structures of these three derivatives were fully optimized at the 6-31G** basis set level using the Gaussian09 program and the B3LYP method of density functional theory. Vibration analysis found that there was no imaginary frequency, indicating that the optimized structure was a minimum point on the potential energy surface. The Monte-Carlo method was used to calculate their theoretical volumes, and then the theoretical density was obtained. The gas phase formation enthalpy of the molecule was calculated using the atomization scheme and the complete basis set method (CBS-4M). Their electrostatic potential parameters were statistically calculated, and the sublimation enthalpy of the molecule was calculated using the formula proposed by Politzer et al., and the solid phase formation enthalpy was obtained. The detonation velocity and detonation pressure were calculated using the Kamlet-Jacobs formula. The results are shown in Table 1.

[0069] In Table 1, except for the compounds of the present invention, the other single explosive compounds are all known single explosives. TNT represents 2,4,6-trinitrotoluene; TATB represents triaminotrinitrobenzene; HNS represents hexanitropine, also known as 6,6'-hexanitrophenylethylene; TACOT represents tetranitrodiphenyltetrazoline; and LLM-126 represents 2,6-dipicrylamino-3,5-dinitropyridine.

[0070] Table 1 Detonation performance parameters of 6-nitro-7-amino-[1,2,4]triazolo[1,5-a]pyrimidine compounds

[0071]

Claims

1. Use of 6-nitro-7-amino-[1,2,4]triazolo[1,5-a]pyrimidine as a single explosive, characterized in that: The structure of the 6-nitro-7-amino-[1,2,4]triazole[1,5-a]pyrimidine is shown below: 。 2. The use according to claim 1, characterized in that The synthesis method of 6-nitro-7-amino-[1,2,4]triazole[1,5-a]pyrimidine comprises the following steps: adding fuming HNO3 and concentrated H2SO4 under 0°C ice-water bath conditions, adding 7-amino-[1,2,4]triazole[1,5-a]pyrimidine under stirring, gradually heating the reaction solution to 80°C and maintaining it for 4.0 hours after the addition, then cooling it to room temperature, pouring ice into the reaction solution, adjusting the pH to 7, and precipitating a white solid; filtering to obtain a white solid, washing, and drying to obtain a white solid product, namely 6-nitro-7-amino-[1,2,4]triazole[1,5-a]pyrimidine.

3. The use according to claim 1, characterized in that The synthesis method of 6-nitro-7-amino-[1,2,4]triazole[1,5-a]pyrimidine comprises the following steps: adding concentrated H2SO4 under 0°C ice-water bath conditions, adding 7-amino-[1,2,4]triazole[1,5-a]pyrimidine under stirring, then adding KNO3 to the reaction solution, gradually heating the reaction solution to 140°C, pouring the reaction solution into crushed ice after the reaction is completed, and white solid precipitating; and filtering to obtain a white solid product, namely 6-nitro-7-amino-[1,2,4]triazole[1,5-a]pyrimidine.

4. The use according to claim 1, characterized in that The synthesis method of 6-nitro-7-amino-[1,2,4]triazole[1,5-a]pyrimidine comprises the following steps: adding 10.0 mL of concentrated HNO3 under 0° C. ice-water bath conditions, adding 7-amino-[1,2,4]triazole[1,5-a]pyrimidine under stirring, then gradually heating the reaction solution to 25° C., stirring the reaction solution at 25° C. for 4.0 hours, and finally gradually heating the reaction solution to 115° C.; after the reaction is completed, pouring the reaction solution into crushed ice to precipitate a white solid; and filtering to obtain a white solid product, namely 6-nitro-7-amino-[1,2,4]triazole[1,5-a]pyrimidine.

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