3-gem-dinitromethyl-1, 2, 4-oxadiazole sodium salt and synthesis method thereof

Abstract

The invention discloses a 3-gem-dinitromethyl-1, 2, 4-oxadiazole sodium salt and a synthesis method thereof, the structural formula of the 3-gem-dinitromethyl-1, 2, 4-oxadiazole sodium salt is shown in the specification, and the preparation method of the 3-gem-dinitromethyl-1, 2, 4-oxadiazole sodium salt comprises the following steps: dispersing 3-gem-dinitromethyl-1, 2, 4-oxadiazole potassium salt in deionized water, slowly dropwise adding an AgNO3 aqueous solution to generate a white precipitate, and stirring and reacting at room temperature for 0.5 h; after the reaction is finished, separating out white precipitate, and filtering, washing and the like to obtain 3-gem-dinitromethyl-1, 2, 4-oxadiazole silver salt; 3-dinitromethyl-1, 2, 4-oxadiazole silver salt is dispersed in deionized water, a NaCl aqueous solution is slowly dropwise added, and the mixture is stirred at the room temperature to react for 0.5 h; after the reaction is finished, filter residues are removed through filtration, filtrate is volatilized at room temperature, crystals are separated out, and the 3-gem-dinitromethyl-1, 2, 4-oxadiazole sodium salt is obtained. The invention provides a 3-gem-dinitromethyl-1, 2, 4-oxadiazole sodium salt compound which is relatively high in density, excellent in energy performance and insensitive, and can be applied to the field of energetic materials.

Description

Technical Field

[0001] The present invention belongs to the field of energetic materials and relates to a sodium salt of 3-gemin-dinitromethyl-1,2,4-oxadiazole and a synthesis method thereof. Background Art

[0002] High-energy-density materials (HEDMs), used in hybrid explosives, propellants, propellants, and explosives, are key materials for achieving "long-range strike" and "high-efficiency damage" in weaponry and play a vital role in weaponry development. Nitrogen-rich five-membered heterocycles, due to their high enthalpy of formation and high oxygen balance values, have become a research hotspot for the synthesis of a new generation of high-energy-density energetic materials. Energetic salts with high lattice energies have high density and excellent stability, making their preparation a highly effective method for creating new energetic compounds. Energetic materials based on ionic salts have advantages over their molecular analogs, such as low vapor pressure (lower toxic vapor generation during processing), high density, and excellent thermal stability. Using anions and cations high in nitrogen content can yield energetic ionic salts with higher formation enthalpy and density due to their high concentration of energetic N=N and C=N bonds. Furthermore, nitrogen-rich compounds decompose primarily to nitrogen gas, making them attractive candidates for environmentally friendly high-energy material applications.

[0003] Isofurazan ring is an important nitrogen-oxygen heterocyclic compound with a high molecular structure tension. It contains high-energy N-O bonds and C-N bonds. The presence of a π structure system in the structure makes the compound highly stable. If explosive groups such as nitro groups are introduced into the parent ring, the energy of such compounds can be further increased. However, the sensitivity of existing geminal dinitroisofurazan energetic ion salts is too high and is not suitable for application. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the present invention aims to provide a sodium salt of 3-dinitromethyl-1,2,4-oxadiazole and a synthesis method thereof, so as to solve the problem that the sensitivity of the existing gem-dinitroisofurazan energetic ion salt is too high.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0006] A sodium salt of 3-gemin-dinitromethyl-1,2,4-oxadiazole, whose structural formula is shown in (I):

[0007]

[0008] The synthesis method of 3-gemin-dinitromethyl-1,2,4-oxadiazole sodium salt comprises the following steps:

[0009] 3-dinitromethyl-l,2,4-oxadiazole potassium salt was dispersed in deionized water, and an AgNO3 aqueous solution was slowly added dropwise, and the reaction was stirred at room temperature for 0.5 h. After the reaction was completed, a white precipitate was precipitated, and 3-dinitromethyl-l,2,4-oxadiazole silver salt was obtained by filtration and washing. NaCl aqueous solution was gradually added dropwise to the 3-dinitromethyl-l,2,4-oxadiazole silver salt, and the reaction solution turned light yellow-green. The filter residue was removed by filtration, and the filtrate crystallized to obtain 3-dinitromethyl-l,2,4-oxadiazole sodium salt.

[0010] The present invention also includes the following technical features:

[0011] Specifically, the molar ratio of 3-dinitromethyl-l,2,4-oxadiazole potassium salt, AgNO3 aqueous solution and NaCl is 1:1.5:0.8.

[0012] Compared with the prior art, the present invention has the following technical effects:

[0013] The preparation method of the sodium salt of 3-gemin-dinitromethyl-l,2,4-oxadiazole of the present invention is simple and efficient; in addition, the crystal density of the sodium salt of 3-gemin-dinitromethyl-l,2,4-oxadiazole synthesized by the present invention is 1.975 g / cm 3 (220K), thermal decomposition temperature 180℃, acceptable sensitivity (IS>40J, FS=144N), it is an energetic compound with high density, excellent energy performance and insensitivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 The single crystal molecular structure diagram of the sodium salt of 3-gemin-dinitromethyl-1,2,4-oxadiazole of the present invention.

[0015] Figure 2 The unit cell diagrams of 3-gemin-dinitromethyl-l,2,4-oxadiazole sodium salt at different angles.

[0016] Figure 3 (a) Crystal structure of 3-dinitromethyl-l,2,4-oxadiazole potassium salt; (b) unit cell structure; (c) and (d) crystal stacking diagrams at different angles. DETAILED DESCRIPTION

[0017] The present invention provides a sodium salt of 3-gemin-dinitromethyl-1,2,4-oxadiazole and a synthesis method thereof. The structural formula of the sodium salt of 3-gemin-dinitromethyl-1,2,4-oxadiazole compound is shown in (I):

[0018]

[0019] The synthetic route of the sodium salt of 3-gemin-dinitromethyl-1,2,4-oxadiazole of the present invention is as follows:

[0020]

[0021] The compound 3-gemin-dinitromethyl-1,2,4-oxadiazole sodium salt (I) of the present invention is prepared by ion exchange between 3-gemin-dinitromethyl-1,2,4-oxadiazole potassium salt (II) and AgNO3 aqueous solution to generate 3-gemin-dinitromethyl-1,2,4-oxadiazole silver salt (III), and then ion exchange between NaCl aqueous solution and 3-gemin-dinitromethyl-1,2,4-oxadiazole silver salt (III) to obtain an aqueous solution of 3-gemin-dinitromethyl-1,2,4-oxadiazole sodium salt (I), and precipitating crystals.

[0022] The synthesis method of 3-gemin-dinitromethyl-1,2,4-oxadiazole sodium salt of the present invention comprises the following steps:

[0023] (1) Preparation of 3-gemin-dinitromethyl-1,2,4-oxadiazole potassium salt:

[0024]

[0025] AHDK was dispersed in triethyl orthoformate, and the catalyst, boron trifluoride etherate, was added dropwise all at once. The reaction system was heated to 75°C and maintained for 23 hours. After completion, crude 3-dinitromethyl-1,2,4-oxadiazole potassium salt (II) was obtained by filtration and washing with ether. The thoroughly dried sample was recrystallized from water to obtain pure 3-dinitromethyl-1,2,4-oxadiazole potassium salt (II).

[0026] (2) Preparation of 3-gemin-dinitromethyl-1,2,4-oxadiazole sodium salt:

[0027] 3-dinitromethyl-1,2,4-oxadiazole potassium salt (II) was dispersed in deionized water, and an AgNO3 aqueous solution was slowly added dropwise. The reaction was stirred at room temperature for 0.5 h. After completion of the reaction, a white precipitate was precipitated, which was filtered and washed to obtain 3-dinitromethyl-1,2,4-oxadiazole silver salt (III). A NaCl aqueous solution was gradually added dropwise to the 3-dinitromethyl-1,2,4-oxadiazole silver salt (III). The reaction solution turned pale yellow-green, and the residue was removed by filtration. The filtrate crystallized to obtain 3-dinitromethyl-1,2,4-oxadiazole sodium salt (I). The molar ratio of 3-dinitromethyl-1,2,4-oxadiazole potassium salt, AgNO3 aqueous solution, and NaCl was 1:1.5:0.8.

[0028] 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 modifications made on the basis of the technical solution of this application fall within the protection scope of the present invention.

[0029] Example 1:

[0030] This example provides a potassium salt of 3-geminal-dinitromethyl-1,2,4-oxadiazole and a synthesis method thereof. AHDK (44 mmol, 8.9 g) was weighed and dispersed in triethyl orthoformate (0.54 mol, 89 mL). A catalyst, 0.2 mL of boron trifluoride etherate, was added dropwise at once. The reaction system was heated and, when the temperature reached 75°C, maintained for 23 hours. After completion of the reaction, crude potassium salt of 3-geminal-dinitromethyl-1,2,4-oxadiazole (II) was obtained by filtration and washing with ether. The thoroughly dried sample was recrystallized from water to obtain pure potassium salt of 3-geminal-dinitromethyl-1,2,4-oxadiazole (II).

[0031] Example 2:

[0032] This embodiment provides a sodium salt of 3-geminal dinitromethyl-1,2,4-oxadiazole and a synthesis method thereof. 3-geminal dinitromethyl-1,2,4-oxadiazole potassium salt (II) (1 mmol, 212 mg) is weighed and prepared into a saturated aqueous solution with deionized water. A saturated aqueous solution of AgNO3 (1.5 mmol, 255 mg) is added dropwise to obtain a milky white suspension. The suspension is stirred at room temperature for 0.5 h, filtered, and washed with deionized water. The filter cake is collected to obtain a slightly moist silver salt of 3-geminal dinitromethyl-1,2,4-oxadiazole (III). The silver salt of 3-geminal dinitromethyl-1,2,4-oxadiazole (III) is transferred to a beaker, and a saturated aqueous solution of NaCl (0.8 mmol, 46.8 mg) is added dropwise. The reaction solution turns yellow-green and is stirred for 0.5 h before being filtered. The filtrate is collected and allowed to stand for evaporation to precipitate crystals to obtain sodium salt of 3-geminal dinitromethyl-1,2,4-oxadiazole (I). The molar ratio of 3-dinitromethyl-l,2,4-oxadiazole potassium salt, AgNO3 aqueous solution and NaCl is 1:1.5:0.8.

[0033] The structure of the sodium salt of 3-gemin-dinitromethyl-1,2,4-oxadiazole prepared in the above example is identified as follows:

[0034] Crystal structure characterization: The single crystal molecular structure of 3-dinitromethyl-1,2,4-oxadiazole sodium salt is as follows Figure 1 Its crystal data and structure refinement parameters are shown in Table 1, and its unit cell diagrams at different angles are shown in Figure 2 As shown, the crystal structure of 3-dinitromethyl-1,2,4-oxadiazole potassium salt is as shown Figure 3 shown.

[0035] Elemental analysis (C3HN4O5Na): Anal. Calcd (%), C, 18.38; H, 0.51; N, 28.58; Found (%), C, 18.49; H, 0.54; N, 28.97

[0036] NMR spectroscopy:1 H-NMR (500MHz, DMSO, δ): 9.59;

[0037] 13 C NMR (125MHz, DMSO, δ): 166.75, 162.19, 122.25;

[0038] Infrared spectrum: IR (KBr), v (cm -1 ): 3441,3167,1556,1525,1462,1437,1379,1348,1331,1273,1243,1191,1142,1092,983,965,897,829,752,717,613;

[0039] Structural identification data confirmed that the substance obtained by the above preparation method is 3-gemin-dinitromethyl-l,2,4-oxadiazole sodium salt.

[0040] Properties of 3-gemin-dinitromethyl-l,2,4-oxadiazole sodium salt:

[0041] (1) Physical and chemical properties

[0042] Appearance: light yellow-green transparent block crystals

[0043] Solubility: Slightly soluble in dimethyl sulfoxide and water, insoluble in ethyl acetate, acetone, etc.

[0044] Decomposition point peak: 213.3℃, ​​293.5℃

[0045] Friction feel (FS): 144N

[0046] Impact (IS): >40J

[0047] Table 1 Crystal data and structure refinement parameters of 3-dinitromethyl-1,2,4-oxadiazole sodium salt

[0048]

[0049]

[0050] (2) Single crystal structure analysis and comparison

[0051] The crystal structure of the sodium salt of 3-gemin-dinitromethyl-l,2,4-oxadiazole of the present invention is an orthorhombic crystal system, which has higher symmetry than the triclinic crystal system in the prior art. This high symmetry may reduce crystal defects. The compact packing mode makes the sodium salt of 3-gemin-dinitromethyl-l,2,4-oxadiazole crystal have higher density and mechanical stability, which means better safety and higher decomposition temperature.

[0052] Application of 3-gemin-dinitromethyl-l,2,4-oxadiazole sodium salt:

[0053] The 3-gemin-dinitromethyl-1,2,4-oxadiazole sodium salt of the present invention can be widely used in the technical fields of explosives, propellants and pyrotechnics.

Claims

1. A sodium salt of 3-dinitromethyl-1,2,4-oxadiazole, characterized in that Its structural formula is shown in (I):

2. The method for synthesizing the sodium salt of 3-gemin-dinitromethyl-1,2,4-oxadiazole according to claim 1, characterized in that: The following steps are involved: 3-dinitromethyl-l,2,4-oxadiazole potassium salt was dispersed in deionized water, and an AgNO3 aqueous solution was slowly added dropwise, and the reaction was stirred at room temperature for 0.5 h. After the reaction was completed, a white precipitate was precipitated, and 3-dinitromethyl-l,2,4-oxadiazole silver salt was obtained by filtration and washing. NaCl aqueous solution was gradually added dropwise to the 3-dinitromethyl-l,2,4-oxadiazole silver salt, and the reaction solution turned light yellow-green. The filter residue was removed by filtration, and the filtrate crystallized to obtain 3-dinitromethyl-l,2,4-oxadiazole sodium salt.

3. The method for synthesizing the sodium salt of 3-gemin-dinitromethyl-1,2,4-oxadiazole according to claim 2, wherein: The molar ratio of 3-dinitromethyl-l,2,4-oxadiazole potassium salt, AgNO3 aqueous solution and NaCl is 1:1.5:0.8.

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