The invention relates to 5, 5apos; azo tetrazole salt and preparation method thereof

Abstract

The invention relates to the technical field of energetic material synthesis, and particularly provides 5, 5 '-azotetrazole salt and a preparation method thereof.The preparation method comprises the following steps that 1, pretreated carbon cloth is immersed in a mixed solution formed by dissolving cobalt nitrate hexahydrate, ammonium fluoride and urea in deionized water, after a hydrothermal reaction, the carbon cloth is taken out and calcined in the air atmosphere, and a precursor is obtained; and finally, the cobaltosic oxide electrode material loaded on the carbon cloth is prepared. 2, dissolving 5-aminotetrazole in an alkaline solution to prepare an electrolyte, forming a three-electrode system by taking the electrolyte and cobaltosic oxide loaded on carbon cloth as a working electrode, a platinum sheet as a counter electrode and a mercury / mercuric oxide electrode as a reference electrode, and electrifying to carry out electrochemical reaction; 3, bromine water is dropwise added into the three-electrode system in the electrifying electrolysis process, hydrochloric acid is dropwise added to adjust the pH value after the reaction is finished, extraction and rotary evaporation are conducted, and the final product 5, 5 '-azotetrazole salt is obtained.

Description

Technical Field

[0001] This invention relates to the field of energetic material synthesis technology, specifically to a method for preparing 5,5'-azotetrazole and the method thereof. Background Technology

[0002] 5,5'-Azotetrazole salts, as potential high-energy-density materials for military and industrial applications, possess high enthalpy of formation, high combustion energy, high detonation velocity, high detonation pressure, low flammability, and low ablation properties. Their high nitrogen content and stable azo structure make them valuable for applications in propellants, explosives, and gas generators. However, traditional synthesis methods often suffer from low yields, difficult purification, high costs, and potential hazards, limiting their further expansion.

[0003] Traditional synthetic methods suffer from drawbacks such as low yield, difficult purification, high cost, and potential hazards. For example, they rely on strong oxidants like potassium permanganate and high temperatures, leading to difficulties in separating byproducts and accompanying safety risks. Although existing oxidation systems have shown great potential for synthesizing energetic materials using purely electrochemical methods, avoiding the shortcomings of traditional methods, some problems still need to be solved in practical applications, such as low production efficiency and insufficient purity, making it difficult to meet the needs of large-scale industrial production and limiting the widespread application of azotetrazole salts.

[0004] Due to these limitations, existing oxidation systems cannot provide a practical solution for efficient, stable, and scalable 5,5'-azotetrazole salts. Summary of the Invention

[0005] To address the aforementioned problems in the prior art, the present invention aims to provide a 5,5'-azotetrazole salt and its preparation method. The present invention employs an electrochemically assisted BrO... - / Br - The synthesis of 5,5'-azotetrazole salt by ion-pair oxidation aims to overcome the inherent defects of traditional chemical oxidation and pure electrochemical oxidation methods. By combining the high efficiency of chemical oxidation with the greenness of electrochemical regeneration, it breaks through the technical bottleneck of existing synthetic routes and prepares 5,5'-azotetrazole salt.

[0006] The technical solution adopted in this invention is as follows: This invention provides a method for preparing 5,5'-azotetrazole salt, comprising the following steps: Step 1: The pretreated carbon cloth is immersed in a mixed solution formed by dissolving cobalt nitrate hexahydrate, ammonium fluoride and urea in deionized water. After hydrothermal reaction, it is taken out and calcined to obtain cobalt tetroxide electrode material loaded on carbon cloth. Step 2: Dissolve 5-aminotetrazole in an alkaline solution to prepare an electrolyte. Use the electrolyte and cobalt tetroxide electrode material loaded on carbon cloth as the working electrode, a platinum sheet as the counter electrode, and a mercury / mercury oxide electrode as the reference electrode to form a three-electrode system, and carry out an electrochemical reaction by passing an electric current through it. Step 3: During the electrolysis process, bromine water is added dropwise to the three-electrode system. After the reaction is completed, the pH value is adjusted, and the mixture is extracted and rotary evaporated to obtain the 5,5'-azotetrazole salt.

[0007] Furthermore, the pretreatment of carbon cloth in step one above includes: ultrasonically cleaning the carbon cloth in sequence with acetone, anhydrous ethanol, deionized water and concentrated nitric acid to remove surface impurities of the carbon cloth. The amounts of cobalt nitrate hexahydrate, ammonium fluoride and urea are in a molar ratio of 1:1:(1~3).

[0008] Furthermore, in step one above, the temperature of the hydrothermal reaction is 100~150℃, and the time is 4~8 h.

[0009] Furthermore, in step one above, the concentrations of cobalt nitrate hexahydrate, ammonium fluoride, and urea are 0.1~0.15 mol / L, 0.1~0.15 mol / L, and 0.1~0.45 mol / L, respectively.

[0010] Furthermore, in step one above, between the hydrothermal reaction and calcination, there is also a step of washing and drying the hydrothermal reaction product with deionized water in sequence. The drying process is carried out in a vacuum oven at a temperature of 40-50°C for 6-8 hours.

[0011] Furthermore, in step one above, the calcination is carried out in a muffle furnace under an air atmosphere. The temperature control mechanism is as follows: the muffle furnace is heated at a rate of 2~5℃ / min, heated to 400~500℃, and then held at this temperature for calcination for 1~3 hours.

[0012] Furthermore, the concentration of 5-aminotetrazole in step two above is 0.018~0.09 mol / L.

[0013] Furthermore, the alkaline solution in step two above is a 0.5~2 mol / L sodium hydroxide solution.

[0014] Furthermore, in step three above, the bromine water is a saturated bromine solution, the molar ratio of bromine water to 5-aminotetrazole is controlled at 2:1, and the pH is adjusted using hydrochloric acid solution with a concentration of 0.5~2 mol / L to 0~1.

[0015] In another aspect, the present invention provides a 5,5'-azotetrazole salt, which is obtained using the 5,5'-azotetrazole salt preparation method of the first aspect of the present invention.

[0016] The advantage of the present invention over the prior art lies in: 1. This invention, through the design of a self-supporting electrode, constructs a three-electrode system that combines chemical oxidation and electrochemistry in the preparation of 5,5'-azotetrazole salt, fully utilizing the high efficiency of chemical oxidation and the greenness of electrochemical regeneration. 2. This invention uses a hydrothermal-calcination method to directly grow cobalt tetroxide nanostructures on conductive carbon cloth. The electrode material prepared by this method has a high specific surface area and abundant active sites, which is beneficial to the electrochemical reaction. 3. In this invention, 5-aminotetrazole is initially oxidized by electrochemical method to generate an active intermediate. Subsequently, bromine water is added dropwise to the electrolyte as a chemical oxidant to further oxidize and couple the intermediate. 4. Under alkaline conditions, electrochemically assisted bromine water oxidation exhibits high selectivity for the oxidative coupling reaction of 5-aminotetrazole. During the reaction, BrO... - / Br - Ion pairs can achieve cyclic conversion, promoting the efficient synthesis of azotetrazole salts. Attached Figure Description

[0017] These and / or other aspects and advantages of the present invention will become clearer and more readily understood from the following detailed description of embodiments of the invention taken in conjunction with the accompanying drawings, wherein: Figure 1 This is a SEM image of the cobalt tetroxide electrode material loaded on carbon cloth obtained in Example 1 of the present invention; Figure 2 An optical photograph of the 5,5'-azotetrazole salt obtained in Example 1 of this invention; Figure 3 The 5,5'-azotetrazole salt obtained in Example 1 of this invention 13 C NMR spectrum; Figure 4 The image shows the UV-vis image of the 5,5'-azotetrazole salt obtained in Example 1 of this invention. Detailed Implementation

[0018] The embodiments of this application will be described in further detail below. Obviously, the described embodiments are only a part of the embodiments of this application, and not an exhaustive list of all embodiments. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other.

[0019] The terms “first,” “second,” etc. (if applicable) in the specification and claims are used to distinguish similar objects and are not necessarily used to describe a particular order or sequence. It should be understood that such data used in this way can be interchanged where appropriate so that the embodiments described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms “comprising” and “having,” and any variations thereof, are intended to cover a non-exclusive inclusion, such as a process, method, system, product, or apparatus that comprises a series of steps or units, not necessarily limited to those explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0020] It should be understood that the term "and / or" used in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0021] In this embodiment of the invention, the specific preparation method includes the following steps: 1) Pre-treat the carbon cloth and then dry it for later use; the pre-treatment process includes ultrasonic cleaning with acetone, anhydrous ethanol, deionized water and concentrated nitric acid in sequence to remove surface impurities from the carbon cloth. 2) Dissolve cobalt nitrate hexahydrate, ammonium fluoride, and urea in deionized water according to a certain molar ratio, and stir thoroughly until completely dissolved to form a homogeneous mixed solution; the concentrations of cobalt nitrate hexahydrate, ammonium fluoride, and urea are 0.1~0.15 mol / L, 0.1~0.15 mol / L, and 0.1~0.45 mol / L, respectively. 3) Immerse the pretreated carbon cloth in step 1) into the mixed solution prepared in step 2), place it in the lining of a hydrothermal reactor, and perform a hydrothermal reaction at 100~150℃ for 4~8h. Then wash with deionized water and dry it in a vacuum oven at 40~50℃ to obtain the precursor material loaded on the carbon cloth. 4) Arrange the carbon loaded with precursor material obtained in step 3) in a muffle furnace and calcine it in an air atmosphere (the muffle furnace heating rate is 2~5°C / min, the temperature is raised to 400~500°C, and the temperature is held for calcination for 1~3 h). After calcination, cool it to room temperature to obtain the cobalt tetroxide electrode material loaded on the carbon cloth. 5) Dissolve 5-aminotetrazole in an alkaline solution and stir ultrasonically to obtain solution A, preferably 0.018~0.09 mol / L of 5-aminotetrazole and 0.5~2 mol / L of sodium hydroxide solution; 6) Using solution A obtained in step 5) as the electrolyte, cobalt tetroxide loaded on carbon cloth obtained in step 4) as the working electrode, platinum sheet as the counter electrode, and mercury / mercury oxide electrode as the reference electrode, a three-electrode reaction is carried out under energized conditions. 7) In the initial stage of the reaction, bromine water is slowly added dropwise to the three-electrode system in step 6). After electrolysis for a period of time, solution B is obtained, and the bromine water is a saturated bromine water solution. 8) Add hydrochloric acid dropwise to solution B obtained in step 7) in small amounts several times to adjust the pH value of solution B to obtain solution C. The concentration of hydrochloric acid solution is 0.5~2 mol / L, and the pH is adjusted to 0~1. 9) Add ethyl acetate to solution C obtained in step 8) for extraction, take the upper layer solution for rotary evaporation, and obtain the final product 5,5'-azotetrazole salt.

[0022] Example 1 A 5,5'-azotetrazole salt and its preparation method, comprising the following steps: Step 1: The pretreated carbon cloth is immersed in a mixed solution formed by dissolving 0.125 mol / L cobalt nitrate hexahydrate, 0.125 mol / L ammonium fluoride and 0.25 mol / L urea in deionized water. After hydrothermal reaction at 120℃ for 6 h, it is taken out and calcined at 450℃ in air atmosphere for 2 h to obtain cobalt tetroxide electrode material loaded on carbon cloth. Step 2: Dissolve 5-aminotetrazole in an alkaline solution to prepare an electrolyte. The concentration of 5-aminotetrazole is 0.09 mol / L, and the alkaline solution is a 1 mol / L sodium hydroxide solution. Using this electrolyte, cobalt tetroxide loaded on carbon cloth as the working electrode, a platinum sheet as the counter electrode, and a mercury / mercury oxide electrode as the reference electrode, a three-electrode system is formed, and an electrochemical reaction is carried out by passing an electric current through it. Step 3: During the electrolysis process, bromine water is added dropwise to the three-electrode system. The molar ratio of bromine water to 5-aminotetrazole is 2:1. After the reaction is completed, the pH value is adjusted, the product is extracted, and the product is rotary evaporated to obtain the final product, sodium 5,5'-azotetrazole.

[0023] Example 2 This embodiment is basically the same as Example 1, except that in step one, the concentrations of cobalt nitrate hexahydrate, ammonium fluoride, and urea are 0.15 mol / L, 0.15 mol / L, and 0.45 mol / L, respectively, and the hydrothermal condition is a reaction at 100°C for 8 h. In step two, the concentration of 5-aminotetrazole is 0.045 mol / L, the alkaline solution used is 2 mol / L sodium hydroxide solution, and the final product is 5,5'-azotetrazole sodium salt.

[0024] Example 3 This embodiment is basically the same as Example 1, except that in step one, the concentrations of cobalt nitrate hexahydrate, ammonium fluoride, and urea are 0.1 mol / L, 0.1 mol / L, and 0.1 mol / L, respectively, and the calcination condition is calcination at 450℃ for 2 h. In step two, the concentration of 5-aminotetrazole is 0.03 mol / L, and the final product is 5,5'-azotetrazole sodium salt.

[0025] Example 4 This embodiment is basically the same as Example 1, except that in step one, the hydrothermal condition is a reaction at 100°C for 4 h, the calcination condition is calcination at 500°C for 1 h, the concentration of 5-aminotetrazole in step two is 0.0225 mol / L, the alkaline solution used is 0.5 mol / L sodium hydroxide solution, and the final product is 5,5'-azotetrazole sodium salt.

[0026] Example 5 This embodiment is basically the same as Example 2, except that in step one the hydrothermal conditions are 150°C for 4 h, and in step two the concentration of 5-aminotetrazole is 0.018 mol / L, and the final product is 5,5'-azotetrazole sodium salt.

[0027] Comparative Example 1 This comparative example is basically the same as Example 1, except that step one is omitted. In step two, pretreated carbon cloth is used as the working electrode, which slows down the reaction rate, reduces the reaction conversion rate, and the yield is about 43.4%.

[0028] Comparative Example 2 This comparative example is basically the same as Example 1, except that in step two, 5-aminotetrazole was dissolved in 1 mol / L sulfuric acid solution to prepare an electrolyte. The solution did not change color, which proves that the target product, 5,5'-azotetrazole sodium salt, was not generated.

[0029] Comparative Example 3 This comparative example is basically the same as Example 1, except that 0.18 mol / L Fe is added dropwise in step three. 3+ In solution, a precipitate forms, the oxidizing power is inhibited, the reaction rate is extremely slow, and almost no color change is observed.

[0030] Table 1 shows the product yields in Examples 1, 2, 3, 4, and 5. The cobalt tetroxide electrode prepared in Example 1 and loaded on carbon cloth was characterized by SEM. The results are shown in [Figure 1]. Figures 1-4 As shown.

[0031] Figure 1The image shows a SEM image of the cobalt tetroxide electrode prepared in Example 1 and loaded on carbon cloth. The morphological features of the electrode can be seen, and the cobalt tetroxide has a nanowire structure.

[0032] Figure 2 An optical photograph of the 5,5'-azotetrazole salt obtained in Example 1.

[0033] The 5,5'-azotetrazole salt obtained in Example 1 was subjected to... 13 The results of the C NMR test are as follows: Figure 3 As shown, a characteristic peak appears at δ = 172.07, corresponding to the tetrazolium carbon of the 5,5'-azotetrazole salt.

[0034] To further validate the synthesized compound, the 5,5'-azotetrazole salt obtained in Example 1 was subjected to UV-Vis spectroscopy analysis, and the results are as follows: Figure 4 As shown, an absorption peak appears at 419 nm, corresponding to the n-π* band of the azo molecule.

[0035] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. For those skilled in the art, other variations or modifications can be made based on the above description. It is impossible to exhaustively list all the implementation methods here. All obvious variations or modifications derived from the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. A method for preparing a 5,5'-azotetrazole salt, characterized in that, Includes the following steps: Step 1: The pretreated carbon cloth is immersed in a mixed solution formed by dissolving cobalt nitrate hexahydrate, ammonium fluoride and urea in deionized water. After hydrothermal reaction, it is taken out and calcined to obtain cobalt tetroxide electrode material loaded on carbon cloth. Step 2: Dissolve 5-aminotetrazole in an alkaline solution to prepare an electrolyte. Use the electrolyte and cobalt tetroxide electrode material loaded on carbon cloth as the working electrode, a platinum sheet as the counter electrode, and a mercury / mercury oxide electrode as the reference electrode to form a three-electrode system, and carry out an electrochemical reaction by passing an electric current through it. Step 3: During the electrolysis process, bromine water is added dropwise to the three-electrode system. After the reaction is completed, the pH value is adjusted, and the mixture is extracted and rotary evaporated to obtain the 5,5'-azotetrazole salt.

2. The method for preparing 5,5'-azotetrazole salt according to claim 1, characterized in that, In step one: The pretreatment of carbon cloth includes ultrasonic cleaning of the carbon cloth in sequence with acetone, anhydrous ethanol, deionized water and concentrated nitric acid to remove surface impurities. The amounts of cobalt nitrate hexahydrate, ammonium fluoride, and urea are in a molar ratio of 1:1:(1~3).

3. The method for preparing 5,5'-azotetrazole salt according to claim 1, characterized in that, The hydrothermal reaction in step one is carried out at a temperature of 100-150℃ for 4-8 hours.

4. The method for preparing 5,5'-azotetrazole salt according to claim 1, characterized in that, In step one, the concentrations of cobalt nitrate hexahydrate, ammonium fluoride, and urea are 0.1~0.15 mol / L, 0.1~0.15 mol / L, and 0.1~0.45 mol / L, respectively.

5. The method for preparing 5,5'-azotetrazole salt according to claim 1, characterized in that, In step one, between the hydrothermal reaction and calcination, there is also a step of washing and drying the hydrothermal reaction product with deionized water in sequence. The drying process is carried out in a vacuum oven at a temperature of 40-50°C for 6-8 hours.

6. The method for preparing 5,5'-azotetrazole salt according to claim 1, characterized in that, In step one, calcination is carried out in a muffle furnace under an air atmosphere. The temperature control mechanism is as follows: the muffle furnace heating rate is 2~5℃ / min, the temperature is raised to 400~500℃, and the calcination is carried out at this temperature for 1~3 hours.

7. The method for preparing 5,5'-azotetrazole salt according to claim 1, characterized in that, The concentration of 5-aminotetrazole in step two is 0.018~0.09 mol / L.

8. The method for preparing 5,5'-azotetrazole salt according to claim 1, characterized in that, The alkaline solution in step two is a 0.5~2 mol / L sodium hydroxide solution.

9. The method for preparing 5,5'-azotetrazole salt according to claim 1, characterized in that, In step three, the molar ratio of bromine water to 5-aminotetrazole is controlled at 2:1, and hydrochloric acid solution is used to adjust the pH to 0-1 with a concentration of 0.5-2 mol / L.

10. A 5,5'-azotetrazole salt, characterized in that, It is obtained using the preparation method described in any one of claims 1 to 9.

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