3, 3 '-diamino-4, 4'-azofurazan and preparation method thereof

Abstract

The invention relates to the technical field of energetic materials, and particularly discloses 3, 3 '-diamino-4, 4'-azofurazan and a preparation method thereof.The target object is synthesized through ionic electrocouple oxidation, the preparation method comprises the following steps that 1, an acid solution of 3, 4-diaminofurazan is prepared, the molar concentration of 3, 4-diaminofurazan in the acid solution is 0.03-0.05 mol / L, and a first solution is obtained; 2, an acid solution of Ce < 4 + > is prepared, the molar concentration of Ce < 4 + > in the acid solution is 0.09-0.25 mol / L, and a second solution is obtained; 3, the reaction temperature is controlled to range from-5 DEG C to 25 DEG C, the first solution is added into the second solution, stirring, centrifuging, filtering, washing, drying and grinding are carried out, and a final sample 3, 3 '-diamino-4, 4'-azofurazan.The synthesis method is easy to operate, low in cost, easy in raw material obtaining and easy to produce, conforms to the green chemistry concept and has the high reaction yield and the high purity.

Description

Technical Field

[0001] This invention relates to the field of energetic materials technology, specifically to a 3,3'-diamino-4,4'-azofuran and its preparation method. Background Technology

[0002] 3,3'-Diamino-4,4'-azofuran is a high-energy-density material with excellent detonation properties and low mechanical sensitivity, making it important for applications in propellants, initiators, and insensitive munitions. However, its industrial application is limited by the high risk and cost of reagents used in existing synthesis methods, as well as numerous side reactions.

[0003] Current oxidation systems often face several problems in practical applications. For example, the oxidizing agents may be hazardous, corrosive, or expensive. Chemical oxidation processes often require stoichiometric or excessive amounts of oxidant, leading to waste generation, and separating products from waste is frequently very difficult. When selecting oxidants, "green chemistry" typically considers the following factors: environmental friendliness, toxicity, mild reaction conditions, harmless byproducts, and biodegradability. Existing oxidation systems, such as sodium hypochlorite, may react to produce chlorine gas or chlorinated organic compounds, requiring strict treatment of reaction wastewater. Due to these limitations, existing oxidation systems cannot provide sufficient safety and oxidation selectivity, resulting in low yields of 3,3'-diamino-4,4'-azofuran. Summary of the Invention

[0004] To address the aforementioned problems, the purpose of this invention is to provide a 3,3'-diamino-4,4'-azofuran and its preparation method. The preparation method of this invention is simple to operate, conforms to the concept of green chemistry, has a high reaction yield, and the obtained product has high purity. This invention uses the Ce4+ oxidative coupling method to prepare the target product, which is simple, low-cost, uses readily available raw materials, and is easy to produce.

[0005] The technical solution adopted in this invention is as follows: This invention provides a method for preparing 3,3'-diamino-4,4'-azofuran, comprising the following steps: Step 1: preparing an acidic solution of 3,4-diaminofuran as a first solution; Step 2: preparing an acidic solution of Ce4+ as a second solution; Step 3: controlling the reaction temperature, adding the first solution to the second solution, stirring, centrifuging, washing, drying, and grinding to obtain the 3,3'-diamino-4,4'-azofuran.

[0006] Furthermore, in step one above, the acidic solution is selected from one or more of sulfuric acid, nitric acid, or hydrochloric acid.

[0007] Furthermore, in step one above, the acidic solution is a 0.5-2 mol / L sulfuric acid solution.

[0008] Furthermore, in step one above, the molar concentration of 3,4-diaminofuran in the acidic solution is 0.03-0.05 mol / L.

[0009] Furthermore, in step two above, the acidic solution of Ce4+ is a Ce4+ sulfate solution.

[0010] Furthermore, in step two above, the amount of acidic Ce4+ solution added is based on a molar ratio of Ce4+ to 3,4-diaminofuran, which is 3:1 to 5:1.

[0011] Furthermore, in step two above, the molar concentration of Ce4+ in the acidic solution is 0.09-0.25 mol / L.

[0012] Furthermore, in step three above, the reaction temperature is controlled between -5 and 25°C.

[0013] The first aspect of the present invention provides a 3,3'-diamino-4,4'-azofuran, which is obtained by the preparation method provided in the first aspect.

[0014] The advantages of the technical solution of this invention are as follows: 1. The preparation method provided by the present invention utilizes the high selectivity of Ce4+ for the oxidative coupling reaction of 3,4-diaminofurozan under acidic conditions. The reaction principle is that the NH bond of the amino group in the raw material 3,4-diaminofurozan is first oxidized by Ce4+ to a monosubstituted hydroxylamine, the hydroxylamine is further oxidized to a nitroso group, and the nitroso compound is then dehydrated and coupled with the raw material 3,4-diaminofurozan to generate the azo compound 3,3'-diamino-4,4'-azofurozan; 2. The preparation method provided by the present invention makes full use of the strong oxidizing property of Ce4+. Furthermore, research has shown that by appropriately increasing the proportion of Ce4+ in the reaction to provide sufficient oxidant for the raw material 3,4-diaminofuran, and by lowering the reaction temperature (controlled at -5-25℃) to avoid excessive oxidation of the raw material 3,4-diaminofuran, the yield and purity of the reaction product can be improved. 3. The Ce3+ produced by the reaction can be converted into Ce4+ through multiple pathways, thus achieving a cycle. 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 3,3'-diamino-4,4'-azofuran obtained according to Example 7 of the present invention; Figure 2The FTIR spectrum of 3,3'-diamino-4,4'-azofuran obtained according to Example 7 of the present invention; Figure 3 The 13C NMR spectrum of 3,3'-diamino-4,4'-azofuran obtained according to Example 7 of the present invention; Figure 4 The image shows the 1H NMR spectrum of 3,3'-diamino-4,4'-azofuran obtained according to Example 7 of the present invention. Figure 5 The image shows a SEM image of 3,3'-diamino-4,4'-azofuran obtained according to Example 7 of the present invention. Figure 6 This is the EDS mapping diagram of 3,3'-diamino-4,4'-azofuran obtained according to Example 7 of the present invention. Detailed Implementation

[0016] 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.

[0017] 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.

[0018] 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.

[0019] Example 1 A method for preparing 3,3'-diamino-4,4'-azofuran includes the following steps: In this embodiment, the molar ratio of 3,4-diaminofuran to Ce4+ is 1:3, and the acidic solution is a 1 mol / L sulfuric acid solution; Step 1: Dissolve 0.03 mol / L 3,4-diaminofuran in 1 mol / L sulfuric acid solution with stirring to obtain the first solution; Step 2: Dissolve 0.09 mol / L cerium(IV) sulfate in 1 mol / L sulfuric acid solution by stirring to obtain the second solution; Step 3: At 25°C, add the first solution to the second solution, stir for 30 min, centrifuge for 10 min, filter, wash with deionized water, dry, and grind to obtain the final sample 3,3'-diamino-4,4'-azofuran.

[0020] Example 2 A method for preparing 3,3'-diamino-4,4'-azofuran is basically the same as that in Example 1, except that the concentration of cerium sulfate in step two is 0.12 mol / L, that is, the molar ratio of 3,4-diaminofuran to Ce4+ is 1:4, and the final product is 3,3'-diamino-4,4'-azofuran.

[0021] Example 3 A method for preparing 3,3'-diamino-4,4'-azofuran is basically the same as that in Example 1, except that the concentration of cerium sulfate in step two is 0.15 mol / L, that is, the molar ratio of 3,4-diaminofuran to Ce4+ is 1:5, and the final product is 3,3'-diamino-4,4'-azofuran.

[0022] Example 4 A method for preparing 3,3'-diamino-4,4'-azofuran is basically the same as in Example 1, except that the concentration of 3,4-diaminofuran is 0.04 mol / L in step one and the concentration of cerium sulfate is 0.2 mol / L in step two, and the final product is 3,3'-diamino-4,4'-azofuran.

[0023] Example 5 This embodiment is basically the same as Example 1, except that the concentration of 3,4-diaminofuran in step one is 0.05 mol / L, the concentration of cerium sulfate in step two is 0.25 mol / L, and the final product is 3,3'-diamino-4,4'-azofuran.

[0024] Example 6 This embodiment is basically the same as Example 5, except that the temperature in step three is set to 15°C, and the final product is 3,3'-diamino-4,4'-azofuran.

[0025] Example 7 This embodiment is basically the same as Example 5, except that the temperature in step three is set to 5°C, and the final product is 3,3'-diamino-4,4'-azofuran.

[0026] Example 8 This embodiment is basically the same as Example 5, except that the temperature in step three is set to -5℃, and the final product is 3,3'-diamino-4,4'-azofuran.

[0027] The product yields and purities in Examples 1-8 are shown in Table 1.

[0028] Table 1 shows the product yields and purity in Examples 1-8.

[0029] As can be seen from Examples 1-3, the yield of the target compound increases with the increase of cerium sulfate concentration. This is because the oxidation of 3,4-diaminofuran to 3,3'-diamino4,4'-azofuran is a four-electron reaction. As the amount of Ce4+ added increases, the number of electrons provided gradually changes from less to more, thus increasing the yield. As can be seen from Examples 3-5, the yield of the target product increases with the increase of the concentration of raw materials and oxidant. This is because a higher concentration of cerium sulfate in an acidic solution has a stronger oxidizing ability. As can be seen from Examples 5-8, the reaction yield and purity increase as the reaction temperature of the raw materials decreases. This is because the low temperature inhibits the oxidation of 3,4-diaminofuran to byproducts to a certain extent, thus improving the selectivity of the reaction. In addition, when the reaction temperature is reduced from 5°C to -5°C, the reaction yield and purity do not increase significantly. Therefore, the more suitable reaction temperature is 5°C. The 3,3'-diamino-4,4'-azofuran obtained in Example 7 was characterized, and the results are shown in [the table below]. Figures 1-4 As shown.

[0030] Figure 1 An optical photograph of 3,3'-diamino-4,4'-azofuran obtained in Example 7.

[0031] The 3,3'-diamino-4,4'-azofuran obtained in Example 7 was subjected to FTIR testing, and the results are as follows: Figure 2As shown, the characteristic peaks at 3442 cm⁻¹ and 3332 cm⁻¹ correspond to the stretching vibration of amino (NH), the characteristic peaks at 1629 cm⁻¹, 1495 cm⁻¹, 1417 cm⁻¹ and 1299 cm⁻¹ correspond to the skeletal vibration of furazan ring, the characteristic peak at 1015 cm⁻¹ corresponds to the stretching vibration of NON in furazan ring, and the characteristic peak at 776 cm⁻¹ corresponds to the bending vibration of amino (-NH₂).

[0032] The 3,3'-diamino-4,4'-azofuran obtained in Example 7 was subjected to 13C NMR analysis, and the results are as follows: Figure 3 As shown, characteristic peaks appear at δ = 156.2 and δ = 151.1, which correspond to the two carbons (C-NH2 and CN=N) of 3,3'-diamino-4,4'-azofuran, respectively. The 3,3'-diamino-4,4'-azofuran obtained in Example 7 was subjected to 1H NMR analysis, and the results are as follows: Figure 4 As shown, a characteristic peak appears at δ = 6.84, corresponding to the NH of 3,3'-diamino-4,4'-azofuran; The 3,3'-diamino-4,4'-azofuran obtained in Example 7 was subjected to SEM testing, and the results are as follows: Figure 5 As shown, the obtained product consists of primary and secondary particles. The secondary particles significantly optimize the performance of the energetic material through their unique structure. Regular morphology (such as spherical shape) enables close packing, increasing charge density and detonation performance, while reducing porosity for stable combustion. The internal nano-primary particles shorten the diffusion distance and accelerate energy release. Furthermore, this structure reduces mechanical sensitivity to improve safety and enhances particle flowability, leading to superior charging processes.

[0033] Figure 6 This is an EDS mapping image of 3,3'-diamino-4,4'-azofuran obtained in Example 7.

[0034] 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 3,3'-diamino-4,4'-azofuran, characterized in that, Includes the following steps: Step 1: Prepare an acidic solution of 3,4-diaminofuran as the first solution; Step 2: Prepare an acidic solution of Ce4+ as the second solution; Step 3: Control the reaction temperature, add the first solution to the second solution, stir, centrifuge, filter, wash, dry, and grind to obtain the 3,3'-diamino-4,4'-azofuran.

2. The method for preparing 3,3'-diamino-4,4'-azofuran according to claim 1, characterized in that, In step one, the acidic solution is selected from one or more of sulfuric acid, nitric acid, or hydrochloric acid.

3. The method for preparing 3,3'-diamino-4,4'-azofuran according to claim 2, characterized in that, In step one, the acidic solution is a 0.5-2 mol / L sulfuric acid solution.

4. The method for preparing 3,3'-diamino-4,4'-azofuran according to claim 1, characterized in that, In step one, the molar concentration of 3,4-diaminofuran in the acidic solution is 0.03-0.05 mol / L.

5. The method for preparing 3,3'-diamino-4,4'-azofuran according to claim 1, characterized in that, In step two, the acidic solution of Ce4+ is a Ce4+ sulfate solution.

6. The method for preparing 3,3'-diamino-4,4'-azofuran according to claim 1, characterized in that, In step two, the amount of acidic Ce4+ solution added is based on a molar ratio of Ce4+ to 3,4-diaminofuran, which is 3:1 to 5:

1.

7. The method for preparing 3,3'-diamino-4,4'-azofuran according to claim 1, characterized in that, In step two, the molar concentration of Ce4+ in the acidic solution is 0.09-0.25 mol / L.

8. The method for preparing 3,3'-diamino-4,4'-azofuran according to claim 1, characterized in that, In step three, the reaction temperature is controlled between -5 and 25°C.

9. A 3,3'-diamino-4,4'-azofuran, characterized in that, It is prepared by the preparation method described in any one of claims 1 to 8.

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