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

Abstract

The invention belongs to the technical field of energetic material synthesis, and particularly relates to 5, 5 '-azotetrazole salt and a preparation method thereof.The preparation method comprises the following steps that 1, under the ice bath condition, alkali metal hydroxide is added into bromine water in batches, magnetic stirring and uniform mixing are conducted, and an alkaline mixed solution is obtained; 2, the alkaline mixed solution is kept in a stirring state, 5-aminotetrazole powder is added, the 5-aminotetrazole powder is added in a batch, small-amount and multiple-time mode, the adding amount each time does not exceed 0.05%-0.1% of the weight of the alkaline mixed solution, after the 5-aminotetrazole powder is added at a time, no bubbles are generated, then the next batch of 5-aminotetrazole powder is added, and after the 5-aminotetrazole powder is added at a time, the 5-aminotetrazole powder is stirred to be uniform; continuously stirring until the solid is completely dissolved; and step 3, dropwise adding hydrochloric acid into the mixed solution obtained in the step 2, adjusting the pH value, adding ethyl acetate, and carrying out extraction and rotary evaporation to finally obtain the solid target product 5, 5 '-azotetrazole salt. An ionic electrocouple oxidation system is adopted, high-temperature and high-pressure conditions are not needed, the reaction can be efficiently completed at normal temperature and normal pressure, operation is easy and safe, and the obtained product is high in purity.

Description

Technical Field

[0001] This invention belongs to the field of energetic materials synthesis technology, specifically relating to a 5,5'-azotetrazole salt and its preparation method. Background Technology

[0002] 5,5'-Azotetrazole salts, as important high-energy materials, have a wide range of applications in propellants, explosives, and pyrotechnics. Their molecular structure contains a high density of nitrogen atoms and azo groups, enabling them to release large amounts of gas and energy through rapid decomposition. Therefore, they are often used as efficient burn rate regulators and gas generators in solid rocket propellants, significantly improving the specific impulse and combustion efficiency of the propellant. In the field of explosives, 5,5'-azotetrazole salts, due to their high detonation velocity and low sensitivity, are used to prepare low-sensitivity, high-energy mixed explosives, meeting the dual requirements of safety and power in military and civilian engineering blasting. However, their traditional synthesis methods typically require high-temperature conditions and face problems such as low yield, difficult purification, and potential hazards, limiting their widespread application.

[0003] Existing chemical synthesis methods for 5,5'-azotetrazole salts have several significant drawbacks, primarily including operational complexity, low yields, and safety concerns. For example, many synthetic routes require high-temperature environments, and the reactions often involve unstable intermediates that can easily trigger explosions or violent decompositions, posing potential hazards. Furthermore, some synthetic methods are accompanied by various side reactions, resulting in low product purity. These drawbacks collectively restrict the widespread application and industrial production of 5,5'-azotetrazole salts. Summary of the Invention

[0004] To address the aforementioned problems, the present invention aims to provide a 5,5'-azotetrazole salt and its preparation method. The preparation method of the present invention is simple and efficient, with widely available and easily obtainable raw materials. The reaction process does not require harsh conditions such as high temperature and high pressure, and can be carried out directly at room temperature. Moreover, the obtained product has high purity, high practical value, and broad application prospects.

[0005] The present invention provides a method for preparing 5,5'-azotetrazole salt, comprising the following steps: Step 1: Under ice bath conditions, add alkali metal hydroxide to bromine water in batches, and mix evenly with magnetic stirring to obtain an alkaline mixed solution; Step 2: While maintaining the alkaline mixture under stirring, add 5-aminotetrazole powder and continue stirring until the solid is completely dissolved; Step 3: Add hydrochloric acid dropwise to the mixed solution obtained in Step 2 to adjust the pH value, then add ethyl acetate, and perform extraction and rotary evaporation to obtain the 5,5'-azotetrazole salt.

[0006] Furthermore, in step one above, the concentration of bromine water is 0.045~0.18 mol / L.

[0007] Furthermore, in step one above, the alkali metal hydroxide powder is selected from at least one of sodium hydroxide, potassium hydroxide, or lithium hydroxide, and the concentration is 0.1~1 mol / L.

[0008] Furthermore, in step one above, the rotation speed of the magnetic stirrer is 200~800 rpm.

[0009] Furthermore, in step two above, the concentration of 5-aminotetrazole in the final mixed solution is 0.0225~0.09 mol / L, and the molar ratio of 5-aminotetrazole to bromine water is 1:2.

[0010] Furthermore, in step two above, the 5-aminotetrazole powder is added in batches in small amounts multiple times, with each addition not exceeding 0.05%-0.1% of the weight of the alkaline mixed solution. After no bubbles are generated after adding the 5-aminotetrazole powder once, the next batch of 5-aminotetrazole powder is added.

[0011] Furthermore, in step three above, the concentration of the hydrochloric acid solution used to adjust the pH is 0.5~2 mol / L, and the pH is adjusted to 0~1.

[0012] Another aspect of the present invention provides a 5,5'-azotetrazole salt, obtained by the preparation method provided in the first aspect of the present invention.

[0013] The beneficial effects of the above technical solution are as follows: 1. This invention synthesizes 5,5'-azotetrazole salt via BrO- / Br- oxidation. The reaction can be carried out efficiently under ambient temperature and pressure conditions, without the need for additional heating or pressurization equipment, significantly reducing energy consumption and equipment investment costs. The operation process is simple and easy to control, and the reaction conditions are mild, avoiding the safety hazards caused by high temperature and high pressure, which can greatly improve the safety of experimental and production processes; 2. This invention utilizes the high oxidizing power of bromine water under alkaline conditions to achieve efficient oxidative coupling of 5-aminotetrazole, thereby improving the selectivity and stability of the reaction and demonstrating feasibility in laboratory and industrial production.

[0014] 3. The post-reaction processing and purification process of this invention is relatively simple. The final target product, 5,5'-azotetrazole salt, can be obtained simply by extraction and rotary evaporation, without the generation of complex byproducts, which significantly reduces equipment occupancy costs. Attached Figure Description

[0015] 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 An optical photograph of the 5,5'-azotetrazole salt obtained according to Example 1 of the present invention; Figure 2 The image shows the FTIR spectrum of the 5,5'-azotetrazole salt obtained according to Example 1 of the present invention. Figure 3 The image shows the 13C NMR spectrum of the 5,5'-azotetrazole salt obtained according to Example 1 of the present invention. Figure 4 The image shows the UV-vis image of the 5,5'-azotetrazole salt obtained according to Example 1 of the present invention. Detailed Implementation 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.

[0016] 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.

[0017] 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.

[0018] Example 1 A method for preparing a 5,5'-azotetrazole salt includes the following steps: Step 1: Under ice bath conditions, slowly add 1 mol / L sodium hydroxide to 0.18 mol / L bromine water and mix thoroughly with magnetic stirring to obtain alkaline mixed solution A; Step 2: While maintaining the alkaline mixed solution A under stirring, slowly add 0.09 mol / L 5-aminotetrazole, controlling the addition rate to avoid excessively high local concentrations. The molar ratio of 5-aminotetrazole to bromine water is 1:2. Continue stirring until the solid is completely dissolved to obtain a clear mixed solution B. Step 3: Add hydrochloric acid dropwise to mixed solution B to adjust the pH value, add ethyl acetate, and perform extraction and rotary evaporation to finally obtain the solid target product 5,5'-azotetrazole sodium salt.

[0019] The 5,5'-azotetrazole salt obtained in Example 1 was characterized, and the results are shown in the figure. Figures 1-4 As shown.

[0020] Figure 1 An optical photograph of the 5,5'-azotetrazole salt obtained in Example 1.

[0021] The 5,5'-azotetrazole salt obtained in Example 1 was subjected to FTIR testing, and the results are as follows: Figure 2 As shown, the characteristic peak at 3501 cm⁻¹ corresponds to the stretching vibration of the OH bond in the water of crystallization; the absorption peaks near 1401 and 739 cm⁻¹ are attributed to the C-N₃ and C-N₂ asymmetric stretching modes in the azotetrazole ring, respectively; the peak at 1607 cm⁻¹ is attributed to the stretching vibrations of the N=N and NN bonds in the azotetrazole ring; the peaks at 1163 and 1051 cm⁻¹ correspond to the CN bond in the azotetrazole ring; and the peak at 773 cm⁻¹ is attributed to the vibration of the tetrazolium ring.

[0022] The 5,5'-azotetrazole salt obtained in Example 1 was subjected to 13C NMR analysis, and the results are as follows: Figure 3 As shown, a characteristic peak appears at δ = 173.76, corresponding to the tetrazolium carbon of the 5,5'-azotetrazole salt.

[0023] The 5,5'-azotetrazole salt obtained in Example 1 was subjected to UV-Vis spectral analysis, and the results are as follows: Figure 4 As shown, an absorption peak appears at 422 nm, corresponding to the n-π* band of the azo molecule.

[0024] Example 2 This embodiment is basically the same as Example 1, except that the concentration of bromine water in step one is 0.09 mol / L, the concentration of 5-aminotetrazole in step two is 0.045 mol / L, and the final product is 5,5'-azotetrazole sodium salt.

[0025] Example 3 This embodiment is basically the same as Example 1, except that the concentration of bromine water in step one is 0.06 mol / L, the concentration of 5-aminotetrazole in step two is 0.03 mol / L, and the final product is 5,5'-azotetrazole sodium salt.

[0026] Example 4 This embodiment is basically the same as Example 1, except that the concentration of bromine water in step one is 0.045 mol / L, the concentration of sodium hydroxide is 0.1 mol / L, the concentration of 5-aminotetrazole in step two is 0.0225 mol / L, and the final product is 5,5'-azotetrazole sodium salt.

[0027] Example 5 This embodiment is basically the same as Example 2, except that in step one, 1 mol / L potassium hydroxide is added to bromine water, and the final product is 5,5'-azotetrazole potassium salt.

[0028] Example 6 This embodiment is basically the same as Example 2, except that in step one, 1 mol / L of lithium hydroxide is added to bromine water, and the final product is 5,5'-azotetrazole lithium salt.

[0029] The yields of the products obtained in Examples 1-6 are shown in Table 1.

[0030] Table 1 shows the product yields in Examples 1, 2, 3, 4, 5, and 6. A comparison of Examples 2, 5, and 6 shows that the effect of changes in hydroxide on product yield is as follows: the yield does not change monotonically with the ionic radius of hydroxide because the crystallization process of the product is the result of competition between "lattice energy" and "hydration energy". A comparison of Examples 1, 2, and 3 shows that the higher the concentration of bromine water and 5-aminotetrazole, the higher the product yield.

[0031] Comparative Example 1 This comparative example is basically the same as Example 1, except that in step one, 1 mol / L sulfuric acid solution was added to 1 mol / L cerium sulfate to obtain an acidic mixed solution, and the target product 5,5'-azotetrazole salt was not obtained.

[0032] Comparative Example 2 This comparative example is basically the same as Example 2, except that the concentration of 5-aminotetrazole added in step two is 0.005 mol / L. The reaction substrate conversion effect is poor, the reaction conversion rate is low, and the yield is only 15%.

[0033] 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: Under ice bath conditions, add alkali metal hydroxide to bromine water in batches, and mix evenly with magnetic stirring to obtain an alkaline mixed solution; Step 2: While maintaining the alkaline mixed solution under stirring, add 5-aminotetrazole powder and continue stirring until the solid is completely dissolved to obtain the final mixed solution; Step 3: Add hydrochloric acid dropwise to the final mixed solution to adjust the pH value, then add ethyl acetate, and perform extraction and rotary evaporation 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 concentration of bromine water is 0.045~0.18 mol / L.

3. The method for preparing 5,5'-azotetrazole salt according to claim 1, characterized in that, In step one, the alkali metal hydroxide is selected from at least one of sodium hydroxide, potassium hydroxide, or lithium hydroxide, and the concentration is 0.1~1 mol / L.

4. The method for preparing 5,5'-azotetrazole salt according to claim 1, characterized in that, In step one, the magnetic stirrer rotates at a speed of 200-800 rpm.

5. The method for preparing 5,5'-azotetrazole salt according to claim 1, characterized in that, In step two, the concentration of 5-aminotetrazole in the final mixed solution is 0.0225~0.09 mol / L, and the molar ratio of 5-aminotetrazole to bromine water is 1:

2.

6. The method for preparing 5,5'-azotetrazole salt according to claim 1, characterized in that, In step two, the 5-aminotetrazole powder is added in batches in small amounts, with each addition not exceeding 0.05%-0.1% of the weight of the alkaline mixed solution. Once no bubbles are generated after adding the 5-aminotetrazole powder, the next batch of 5-aminotetrazole powder is added.

7. The method for preparing 5,5'-azotetrazole salt according to claim 1, characterized in that, In step three, the concentration of hydrochloric acid solution used to adjust the pH is 0.5~2 mol / L, and the pH is adjusted to 0~1.

8. A 5,5'-azotetrazole salt, characterized in that, Obtained by the preparation method described in any one of claims 1 to 7.

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