Non-hygroscopic dinitramide compound and preparation method thereof

Abstract

The invention discloses a non-hygroscopic dinitramide compound and a preparation method thereof, a series of non-hygroscopic dinitramide compounds are synthesized by introducing cations capable of forming strong hydrogen-bond interaction with N (NO2) <-> to replace NH4 < + >, and the structural characteristics of the compounds are as follows: dinitramide radicals are used as anions, and N (NO2) <-> and N (NO2) <-> are used as negative ions; and the protonated pyridine or pyrimidine compound is a cation. The compound prepared by the invention has the advantages of no moisture absorption, low sensitivity, simple synthesis, environmental protection and the like, the synthesis method is simple and efficient, the cation adjustability is strong, and the compound has very high application potential in the field of energetic materials.

Description

Technical Field

[0001] The present invention relates to the technical field of energetic materials, and more particularly to a class of non-hygroscopic dinitramide compounds and their preparation methods. Background Art

[0002] Ammonium dinitramide (ADN) has become an excellent energetic material due to its high energy density, good thermal stability, low signature, environmental friendliness, etc., and is one of the research hotspots in the field of solid propellant oxidants. However, the strong hygroscopicity problem severely limits its large-scale engineering application. Currently, the methods for reducing the hygroscopicity of ADN mainly include spheronization technology, coating technology, and eutectic technology. The spheronization technology spheronizes ADN through methods such as emulsion crystallization, spray drying, and microfluidics, but this method can only delay the hygroscopic rate of ADN. The coating technology coats materials such as surfactants and hydrophobic polymers on the surface of ADN to prevent ADN from contacting with water molecules. CN109574776A discloses a preparation method of graphene-coated spheronized ammonium dinitramide, including preparing spheronized ammonium dinitramide by using a normal temperature or low temperature recrystallization method under the co-induction of ultrasonic waves and nitramine explosives; then preparing a graphene-coated spheronized ammonium dinitramide composite material by using an ultrasonic anti-solvent method. However, due to factors such as process conditions and the coating layer not being dense enough, this method can only reduce the hygroscopicity of ADN to a certain extent. The eutectic technology has great application prospects, but there are few reports currently, and it is difficult to achieve engineering application.

[0003] Research shows that the reason for the strong hygroscopicity of ADN is that the surface energy of ADN is high, and it tends to absorb water in the air to reduce its surface energy. In addition, the NH4 + and N(NO2) - in the ADN molecule will combine with water molecules through hydrogen bonds, thereby absorbing moisture from the ambient atmosphere and further increasing its hygroscopicity.

[0004] Currently, although the prior art uses various means to carry out hygroscopicity improvement treatment on the easily hygroscopic ADN and has achieved certain improvement results. However, for practical applications, it is still urgently necessary to explore more effective technologies to further achieve anti-hygroscopic modification of ADN. Summary of the Invention

[0005] In view of this, in order to overcome the above problems in the prior art, the present invention provides a class of non-hygroscopic dinitramide compounds and their preparation methods through multiple research and experiments. This method replaces NH4 - with a cation that can form a strong hydrogen bond with N(NO2) +, a series of non-hygroscopic dinitramide compounds were synthesized, which are characterized by having dinitramide anions and protonated pyridine or pyrimidine compounds as cations, and have the advantages of non-hygroscopicity, low sensitivity, simple synthesis, and environmental friendliness.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] On the one hand, the present invention provides a class of non-hygroscopic dinitramide compounds, the anion of which is dinitramide and has the following structural formula:

[0008]

[0009] The cation of the dinitramide compound is a protonated pyridine or pyrimidine compound and has the following structure:

[0010]

[0011] Among them, the substituents R1, R2, and R3 are each independently selected from a hydrogen atom, a halogen atom, an amino group, a nitro group, or a methoxy group.

[0012] On the other hand, the present invention provides a method for preparing a non-hygroscopic dinitramide compound, which includes the following steps:

[0013] S1: Dissolve ammonium dinitramide in a solvent in a mass fraction of 1 to 60%, and the solvent is any one of water, methanol, ethanol, or isopropanol;

[0014] S2: Dissolve a pyridine, pyrimidine, or pyrazine compound in a solvent in a mass fraction of 1 to 60%, and the solvent is any one of water, methanol, ethanol, isopropanol, ethyl acetate, acetonitrile, dimethyl sulfoxide, or N,N-dimethylformamide;

[0015] S3: Mix the two solutions obtained in step S1 and step S2, stir evenly, and obtain a solid product after evaporating the solvent, that is, the target product dinitramide compound.

[0016] Further, the temperature required for dissolution is 0 to 90°C; the temperature required for evaporating the solvent is 0 to 30°C.

[0017] Further, the temperature required for dissolution is 20 to 50°C; the temperature required for evaporating the solvent is 20 to 30°C.

[0018] Further, the molar ratio of ammonium dinitramide to the pyridine or pyrimidine compound is 1:1.

[0019] Further, in step S1, the mass fraction of ammonium dinitramide in the solvent is 10 to 20%.

[0020] Further, in step S2, the mass fraction of the pyridine-based, pyrimidine-based or pyrazine-based compound in the solvent is 10-20%.

[0021] Further, the pyridine-based compound is 2,6-diaminopyridine or phenanthroline.

[0022] Further, the pyrimidine-based compound is 2,4,6-triaminopyrimidine or 2,6-diamino-4-methoxypyrimidine.

[0023] The beneficial effects of the present invention compared with the prior art are as follows:

[0024] The compound prepared by the present invention has the advantages of non-hygroscopicity, low sensitivity, simple synthesis, environmental friendliness, etc. The compound synthesis method disclosed by the present invention is simple and efficient, with strong cation tunability and high application potential in the field of energetic materials. Description of the Drawings

[0025] Figure 1 It is the crystal structure diagram of the dinitramide salt of 2,6-diaminopyridine prepared in Example 1 of the present invention.

[0026] Figure 2 It is the 1 H NMR spectrum of the dinitramide salt of 2,6-diaminopyridine prepared in Example 1 of the present invention.

[0027] Figure 3 It is the hygroscopicity test chart of the dinitramide salt of 2,6-diaminopyridine prepared in Example 1 of the present invention.

[0028] Figure 4 It is the crystal structure diagram of the dinitramide salt of 2,4,6-triaminopyrimidine prepared in Example 2 of the present invention.

[0029] Figure 5 It is the 1 H NMR spectrum of the dinitramide salt of 2,4,6-triaminopyrimidine prepared in Example 2 of the present invention.

[0030] Figure 6 It is the hygroscopicity test chart of the dinitramide salt of 2,4,6-triaminopyrimidine prepared in Example 2 of the present invention.

[0031] Figure 7 It is the crystal structure diagram of the dinitramide salt of phenanthroline prepared in Example 3 of the present invention.

[0032] Figure 8 It is the hygroscopicity test chart of the dinitramide salt of phenanthroline prepared in Example 3 of the present invention.

[0033] Figure 9This is the crystal structure diagram of the dinitramide salt of 2,6-diamino-4-methoxypyrimidine prepared in Example 4 of the present invention.

[0034] Figure 10 This is the hygroscopicity test chart of the dinitramide salt of 2,6-diamino-4-methoxypyrimidine prepared in Example 4 of the present invention. Detailed implementation manners

[0035] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the present invention will be further described below in conjunction with the embodiments. The described embodiments are only a part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the protection scope of the present invention. For those conditions not specified in the embodiments, they are carried out according to the conventional conditions or the conditions recommended by the manufacturer. For the reagents or instruments not specified by the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0036] Example 1

[0037] At 20 °C, 1.24 g of ammonium dinitramide (10 mmol) was dissolved in 10 ml of methanol, and an equimolar amount of 2,6-diaminopyridine was dissolved in 10 ml of methanol. Then the two were mixed and left at room temperature for 48 h. After the solvent had evaporated completely, a yellow solid, namely the dinitramide salt of 2,6-diaminopyridine, was obtained with a yield of 95%. Figure 1 This is the crystal structure of the dinitramide salt of 2,6-diaminopyridine. Figure 2 This is the 1 1H NMR spectrum of the dinitramide salt of 2,6-diaminopyridine. 1 g of the dinitramide salt of 2,6-diaminopyridine was subjected to a hygroscopicity test at a temperature of 20 °C and a relative humidity of 75%. The weight gain rate after 15 days was 0.01%, showing non-hygroscopic properties. Figure 3 This is the hygroscopicity test chart of the dinitramide salt of 2,6-diaminopyridine. The impact sensitivity of the dinitramide salt of 2,6-diaminopyridine > 50 J, and the friction sensitivity > 240 N. It is a low-sensitivity energetic material.

[0038] Example 2

[0039] At 30 °C, 1.24 g of ammonium dinitramide (10 mmol) was dissolved in 10 ml of water, and an equimolar amount of 2,4,6-triaminopyrimidine was dissolved in 10 ml of water. Then the two were mixed and left at room temperature for 1 h. A large amount of orange-yellow solid precipitated. After filtration and drying, the dinitramide salt of 2,4,6-triaminopyrimidine was obtained with a yield of 98%. Figure 4 This is the crystal structure of the dinitramide salt of 2,4,6-triaminopyrimidine. Figure 5For the dinitramide salt of 2,4,6-triaminopyrimidine 1 1H NMR spectrum. 1 g of the dinitramide salt of 2,4,6-triaminopyrimidine was subjected to a hygroscopicity test at a temperature of 20 °C and a relative humidity of 75%. The weight gain rate after 15 days was 0.02%, showing non-hygroscopic properties. Figure 6 Hygroscopicity test chart for the dinitramide salt of 2,4,6-triaminopyrimidine. The impact sensitivity of the dinitramide salt of 2,4,6-triaminopyrimidine > 50 J, and the friction sensitivity > 240 N. It is a low-sensitivity energetic material.

[0040] Example 3

[0041] At 50 °C, 1.24 g of ammonium dinitramide (10 mmol) was dissolved in 10 ml of methanol, and an equimolar amount of phenapyridine was dissolved in 10 ml of ethyl acetate. Then the two were mixed and left at room temperature for 48 h. After the solvent had evaporated completely, the dinitramide salt of phenapyridine was obtained with a yield of 87%. Figure 7 Crystal structure of the dinitramide salt of phenapyridine. 1 g of the dinitramide salt of phenapyridine was subjected to a hygroscopicity test at a temperature of 20 °C and a relative humidity of 75%. The weight gain rate after 15 days was 0.05%, showing non-hygroscopic properties. Figure 8 Hygroscopicity test chart for the dinitramide salt of phenapyridine. The impact sensitivity of the dinitramide salt of phenapyridine > 50 J, and the friction sensitivity > 240 N. It is a low-sensitivity energetic material.

[0042] Example 4

[0043] 1.24 g of ammonium dinitramide (10 mmol) was dissolved in 10 ml of ethanol, and an equimolar amount of 2,6-diamino-4-methoxypyrimidine was dissolved in 10 ml of tetrahydrofuran. Then the two were mixed and left at room temperature for 48 h. After the solvent had evaporated completely, a white solid, namely the dinitramide salt of 2,6-diamino-4-methoxypyrimidine, was obtained with a yield of 88%. Figure 9 Crystal structure of the dinitramide salt of 2,6-diamino-4-methoxypyrimidine. 1 g of the dinitramide salt of 2,6-diamino-4-methoxypyrimidine was subjected to a hygroscopicity test at a temperature of 20 °C and a relative humidity of 75%. The weight gain rate after 15 days was 0.02%, showing non-hygroscopic properties. Figure 10 Hygroscopicity test chart for the dinitramide salt of 2,6-diamino-4-methoxypyrimidine. The impact sensitivity of the dinitramide salt of 2,6-diamino-4-methoxypyrimidine > 50 J, and the friction sensitivity > 240 N. It is a low-sensitivity energetic material.

[0044] Example 5

[0045] Dissolve 0.124 g of ammonium dinitramide (1 mmol) in 5 ml of ethanol. Dissolve an equimolar amount of 4-bromo-2,6-diaminopyridine in 5 ml of tetrahydrofuran. Then mix the two solutions and let them stand at room temperature for 48 h. After the solvent has evaporated completely, a white solid, namely the dinitramide salt of 4-bromo-2,6-diaminopyridine, is obtained with a yield of 80%. Perform a hygroscopicity test on 0.1 g of the dinitramide salt of 4-bromo-2,6-diaminopyridine at a temperature of 20 °C and a relative humidity of 75%. The weight gain rate after 15 days is 0.2%, indicating non-hygroscopic properties. The impact sensitivity of the dinitramide salt of 4-bromo-2,6-diaminopyridine is >50 J, and the friction sensitivity is >240 N. It is a low-sensitivity energetic material.

[0046] Example 6

[0047] Dissolve 0.124 g of ammonium dinitramide (1 mmol) in 5 ml of water. Dissolve an equimolar amount of 5-nitro-2,4,6-triaminopyrimidine in 10 ml of water. Then mix the two solutions and let them stand at room temperature for 48 h. After the solvent has evaporated completely, a yellow solid, namely the dinitramide salt of 5-nitro-2,4,6-triaminopyrimidine, is obtained with a yield of 92%. Perform a hygroscopicity test on 0.1 g of the dinitramide salt of 5-nitro-2,4,6-triaminopyrimidine at a temperature of 20 °C and a relative humidity of 75%. The weight gain rate after 15 days is 0.2%, indicating non-hygroscopic properties. The impact sensitivity of the dinitramide salt of 5-nitro-2,4,6-triaminopyrimidine is >50 J, and the friction sensitivity is >240 N. It is a low-sensitivity energetic material.

[0048] A class of non-hygroscopic dinitramide compounds has been prepared in this invention, which features non-hygroscopicity, low sensitivity, simple synthesis, and environmental friendliness. The disclosed compound synthesis method in this invention is simple and efficient, with strong cation tunability, and has high application potential in the field of energetic materials.

[0049] It should be noted that the above-described embodiments are only the preferred embodiments of the present invention. For those of ordinary skill in the art, without departing from the principle of the present invention, several modifications, improvements, and equivalent substitutions can be made to the present invention, and these modifications, improvements, and equivalent substitutions are also considered to fall within the protection scope of the claims of the present invention.

Claims

1. A class of non-hygroscopic dinitramide compounds, characterized in that, The anion of the dinitramide compound is dinitramide, having the following structural formula: The cation of the dinitramide compound is a protonated pyridine or pyrimidine compound, having the following structure: Among them, the substituents R1, R2, and R3 are each independently selected from a hydrogen atom, a halogen atom, an amino group, a nitro group, or a methoxy group.

2. A method for preparing a non-hygroscopic dinitramide compound according to claim 1, characterized in that, It includes the following steps: S1: Dissolve ammonium dinitramide in a solvent in a mass fraction of 1-60%, and the solvent is any one of water, methanol, ethanol, or isopropanol. S2: Dissolve a pyridine, pyrimidine, or pyrazine compound in a solvent in a mass fraction of 1-60%, and the solvent is any one of water, methanol, ethanol, isopropanol, ethyl acetate, acetonitrile, dimethyl sulfoxide, or N,N-dimethylformamide. S3: Mix the two solutions obtained in step S1 and step S2, stir evenly, and volatilize the solvent to obtain a solid product, which is the target product dinitramide compound.

3. The preparation method of the dinitramide compound according to claim 2, wherein, The temperature required for dissolution is 0-90°C; the temperature required for volatilizing the solvent is 0-30°C.

4. The preparation method of the dinitramide compound according to claim 2, wherein The temperature required for dissolution is 20-50°C; the temperature required for volatilizing the solvent is 20-30°C.

5. The method for preparing the dinitramide compound according to claim 2, characterized in that, The molar ratio of ammonium dinitramide to the pyridine or pyrimidine compound is 1:

1.

6. The preparation method of the dinitramide compound according to claim 2, characterized in that, In step S1, the mass fraction of ammonium dinitramide in the solvent is 10-20%.

7. The preparation method of the dinitramide compound according to claim 2, characterized in that, In step S2, the mass fraction of the pyridine, pyrimidine, or pyrazine compound in the solvent is 10-20%.

8. The preparation method of the dinitramide compound according to claim 2, characterized in that, The pyridine compound is 2,6-diaminopyridine, phenanthroline, or 4-bromo-2,6-diaminopyridine.

9. The preparation method of the dinitramide compound according to claim 2, characterized in that, The pyrimidine compound is 2,4,6-triaminopyrimidine, 2,6-diamino-4-methoxypyrimidine, or 5-nitro-2,4,6-triaminopyrimidine.

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