3, 3 '-diamino-4, 4'-azofurazan and ionic couple and electrochemical synergistic synthesis method thereof

Abstract

The invention relates to the technical field of ionic couple and electrochemical synergistic synthesis, in particular to 3, 3 '-diamino-4, 4'-azofurazan and an ionic couple and electrochemical synergistic synthesis method thereof, and the synthesis method comprises the following steps: 1, preparing CC-Co3O4: adopting nitric acid hexahydrate, ammonium fluoride, urea and carbon cloth as raw materials, and preparing the CC-Co3O4 through a hydrothermal method; 2, preparing an acidic solution of 3, 4-diaminofurazan to obtain a first solution; 3, preparing an acid solution of Ce < 4 + > to obtain a second solution; and 4, carrying out an electrocatalytic oxidation reaction by taking CC-Co3O4 as an anode, a platinum sheet as a counter electrode and the first solution as an electrolyte, dropwise adding the second solution into the electrolyte in the electrocatalytic process, and stirring, centrifuging, washing, drying and grinding after the second solution is dropwise added to obtain the 3, 3 '-diamino-4, 4'-azofurazan.

Description

Technical Field

[0001] This invention relates to the field of ion-coupled and electrochemical synergistic synthesis technology, specifically to a method for the synergistic synthesis of 3,3'-diamino-4,4'-azofuran and its ion-coupled and electrochemical synergistic synthesis. Background Technology

[0002] 3,3'-Diamino-4,4'-azofuran is an important high-nitrogen furazan compound with advantages such as good heat resistance, high standard heat of formation, low sensitivity, small critical diameter, and excellent detonation performance. It has been widely used in solid rocket propellants, civil blasting, and traffic safety. Traditional methods for synthesizing 3,3'-diamino-4,4'-azofuran typically face challenges such as low target product concentration, complex operating procedures, inability to reuse oxidants, harsh reaction conditions, and difficulties in purification.

[0003] Current oxidation systems often face several problems in practical applications, such as the hazardous nature of the oxidizing agents, their inability to be recycled, and their high cost. For example, sodium hypochlorite may react to produce toxic gases such as chlorine or chlorinated organic compounds, and it requires a stringent operating environment; potassium permanganate, during catalytic oxidation, is converted into manganate (MnO₂). 3- The reaction wastewater needs to be strictly treated; although the electrochemical oxidation method has less pollution, its production efficiency is low and it cannot achieve high-efficiency production of the target product.

[0004] Due to these limitations, existing reaction systems cannot provide sufficient safety and efficiency in product preparation, resulting in low yields of 3,3'-diamino-4,4'-azofuran and severe wastewater pollution. Summary of the Invention

[0005] To address the aforementioned problems, the present invention aims to provide a method for preparing 3,3'-diamino-4,4'-azofuran, which combines ion-coupled and electrochemical processes in a synergistic manner. This method is simple to operate, conforms to the concept of green chemistry, has high reaction efficiency and product purity, low cost, recyclable oxidant, high yield and fast efficiency, and the oxidant can be reused after repair.

[0006] The technical solution of the present invention is that, on one hand, the present invention provides a method for the synergistic synthesis of 3,3'-diamino-4,4'-azofuran by ion-coupled and electrochemical methods, comprising the following steps: Step 1: Preparation of CC-Co3O4: CC-Co3O4 is prepared by hydrothermal method using nitric acid hexahydrate, ammonium fluoride, urea and carbon cloth as raw materials. Step 2: Prepare an acidic solution of 3,4-diaminofuran to obtain the first solution; Step 3: Preparation of Ce 4+ The acidic solution was used to obtain a second solution; Step 4: Using CC-Co3O4 as the anode, a platinum sheet as the counter electrode, and the first solution as the electrolyte, an electrocatalytic oxidation reaction is carried out. During the electrocatalytic process, the second solution is added dropwise to the electrolyte. After the second solution is added, the mixture is stirred, centrifuged, washed, dried, and ground to obtain the 3,3'-diamino-4,4'-azofuran.

[0007] Furthermore, in step one above, the temperature of the hydrothermal reaction is maintained at 130-150℃ so that Co3O4 has a spinel structure.

[0008] Furthermore, in step two above: the acidic solution is selected from one or more of sulfuric acid, nitric acid, or hydrochloric acid; in step three: Ce is prepared... 4+ The method for preparing the acidic solution is as follows: Cerium sulfate is dissolved in an acidic solution under stirring conditions. The acidic solution is one or more of sulfuric acid, nitric acid, or hydrochloric acid. The concentration of the acidic solution is the same as that of the acidic solution in step two. The acidic solution contains Ce... 4+ The molar concentration is 0.5-2.5 mol / L.

[0009] Furthermore, the acidic solution mentioned in step two above is a sulfuric acid solution.

[0010] Furthermore, the preparation method of the present invention also includes step five: containing Ce 3+ The electrolyte supernatant was oxidized and repaired to Ce using a DC power supply. 4+ Used in step three, Ce 4+ The raw materials.

[0011] Furthermore, the Ce mentioned above 3+ Oxidative repair to Ce 4+ The voltage of the DC power supply used is 1-2 V.

[0012] Furthermore, in the synthesis method of this invention, 3,4-diaminofuran and Ce 4+ The molar ratio is 1:0.5-1:2.5.

[0013] Furthermore, the voltage applied in the electrocatalytic reaction in step four above is 1.2 V vs. RHE.

[0014] Furthermore, the drying temperature in step four above is 40-50℃.

[0015] In another aspect, the present invention also provides 3,3-diamino-4,4-azofuran obtained by the above-described synthetic method.

[0016] The beneficial effects of the technical solution of this invention are: 1. In the synthesis method of the present invention, under the conditions of synergistic oxidation by ion-couple and electrochemical oxidation, the oxidant Ce 4+ The hydroxyl radicals generated by the self-supporting anode-loaded Co3O4 carbon cloth (CC-Co3O4) under an electric field exhibit high selectivity and reaction rate for the oxidative coupling reaction of 3,4-diaminofuran, enabling efficient production of 3,4-diaminofuran oxidation and avoiding waste caused by incomplete reaction of raw materials. 2. In the synthesis method of this invention, the defined concentration and molar ratio, combined with an acidic reaction environment, can ensure the optimal Ce concentration. 4+ It selectively attacks specific amino sites of 3,4-diaminofuran, promoting directional coupling reactions and avoiding Ce-related issues. 4+ Excessive amounts may lead to insufficient contact with the substrate, or due to Ce 4+ Insufficient raw material self-polymerization byproducts; 3. In the synthesis method of the present invention, the Ce produced by the reaction 3+ Ce can be repaired through electrochemical oxidation. 4+ This allows for recycling and avoids the use of strong oxidants, making it environmentally friendly. Furthermore, the reaction product 3,3'-diamino-4,4'-azofuran has low solubility under acidic conditions, making it easy to separate from the reaction solution. Attached Figure Description

[0017] Figure 1 Raman plot of 3,3'-diamino-4,4'-azofuran obtained according to Example 4 of the present invention; Figure 2 The 13C NMR spectrum of 3,3'-diamino-4,4'-azofuran obtained according to Example 4 of the present invention; Figure 3 Ce before and after repair, as obtained according to Embodiment 4 of the present invention 4+ The ultraviolet absorption spectrum of the solution. 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.

[0018] 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.

[0019] 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.

[0020] The specific preparation method includes the following steps: 1) Cobalt nitrate hexahydrate, ammonium fluoride, urea and carbon were placed in a high-pressure reactor containing deionized water and subjected to high-temperature hydrothermal treatment to obtain carbon cloth loaded with Co3O4, namely CC-Co3O4. 2) Dissolve 3,4-diaminofuran in an acidic solution under stirring to obtain solution A; 2) Ce 4+ Dissolved by stirring in an acidic solution, resulting in solution B. Solution B contains Ce. 4+ The concentration is 0.5-2.5 mol / L; 3) Using the material prepared in step one as the anode, a platinum sheet as the counter electrode, and solution A obtained in step two as the electrolyte, electrocatalytic oxidation of 3,4-diaminofuran is carried out in the electrocatalytic system. During the electrocatalytic process, solution B is added dropwise to the electrolyte. After the addition is completed, the solution is centrifuged to obtain solution C and sample A. 4) Wash sample A with deionized water to obtain sample B; 5) Dry sample B in a vacuum oven at 50°C to obtain sample C; 6) Grind sample C to obtain the final sample 3,3'-diamino-4,4'-azofuran; 7) By using a DC power supply to energize solution C, the Ce in the solution can be removed. 3+ Oxidized to Ce 4+ .

[0021] The acidic solution is selected from at least one of sulfuric acid, nitric acid, or hydrochloric acid, preferably an aqueous solution of sulfuric acid, and the pH value of the solution is controlled within the range of 0-1 to ensure the high oxidizing power of the catalyst.

[0022] The Ce 4+ It is cerium sulfate.

[0023] The centrifuge has a rotation speed of 5000~8000 rpm.

[0024] The product after the reaction is washed with deionized water and then dried in a vacuum oven at a temperature of 40-50°C.

[0025] Example 1 A method for preparing 3,3'-diamino-4,4'-azofuran includes the following steps: In this embodiment, 3,4-diaminofuran and Ce 4+ The molar ratio is 1:0.5, and the acidic solution is a 1 mol / L sulfuric acid solution; Step 1: Cobalt nitrate hexahydrate, ammonium fluoride, urea and carbon are placed in a high-pressure reactor containing deionized water and hydrothermally heated to obtain carbon cloth loaded with Co3O4, namely CC-Co3O4. Step 2: Dissolve 1 mol / L 3,4-diaminofuran in 1 mol / L sulfuric acid solution with stirring to obtain the first solution; Step 3: Dissolve 0.5 mol / L cerium sulfate in sulfuric acid solution by stirring to obtain the second solution; Step 4: Using the material prepared in Step 1 as the anode, a platinum sheet as the counter electrode, and the first solution as the electrolyte, electrocatalytic oxidation of 3,4-diaminofuran is carried out in the electrocatalytic system. During the electrocatalytic process, the second solution is added dropwise to the electrolyte. After the addition is completed, the mixture is stirred, centrifuged, washed, dried, and ground to obtain the final sample 3,3'diamino-4,4'-azofuran. Step 5: Add Ce 3+ The electrolyte supernatant was oxidized and repaired to Ce using a 1.5 V DC power supply. 4+ It can then be used in step 3 to achieve the recycling of the oxidant.

[0026] Example 2 A method for preparing 3,3'-diamino-4,4'-azofuran includes the following steps: In this embodiment, 3,4-diaminofuran and Ce 4+ The molar ratio is 1:1, and the acidic solution is a 1 mol / L sulfuric acid solution; Step 1: Cobalt nitrate hexahydrate, ammonium fluoride, urea and carbon are placed in a high-pressure reactor containing deionized water and hydrothermally heated to obtain carbon cloth loaded with Co3O4, namely CC-Co3O4. Step 2: Dissolve 1 mol / L of 3,4-diaminofuran in sulfuric acid solution with stirring to obtain the first solution; Step 3: Dissolve 1 mol / L cerium sulfate in a 1 mol / L sulfuric acid solution by stirring to obtain a second solution; Step 4: Using the material prepared in Step 1 as the anode, a platinum sheet as the counter electrode, and the solution obtained in Step 2 as the electrolyte, electrocatalytic oxidation of 3,4-diaminofuran is carried out in the electrocatalytic system. During the electrocatalytic process, a second solution is added dropwise to the electrolyte. After the addition is completed, the mixture is stirred, centrifuged, washed, dried, and ground to obtain the final sample 3,3'-diamino-4,4'-azofuran. Step 5: Add Ce 3+ The electrolyte supernatant was oxidized and repaired to Ce using a 1.6 V DC power supply. 4+ This enables the recycling of oxidants; Example 3 The preparation method of 3,3'-diamino-4,4'-azofuran through ion-coupled and electrochemical synergistic synthesis includes the following steps: In this embodiment, preferably, 3,4-diaminofuran and Ce 4+ The molar ratio is 1:1.5, and the acidic solution is a 1 mol / L sulfuric acid solution; Step 1: Cobalt nitrate hexahydrate, ammonium fluoride, urea and carbon are placed in a high-pressure reactor containing deionized water and hydrothermally heated to obtain carbon cloth loaded with Co3O4, namely CC-Co3O4. Step 2: Dissolve 1 mol / L of 3,4-diaminofuran in sulfuric acid solution with stirring to obtain the first solution; Step 3: Dissolve 1.5 mol / L cerium sulfate in a 1 mol / L sulfuric acid solution by stirring to obtain a second solution; Step 4: Using the material prepared in Step 1 as the anode, a platinum sheet as the counter electrode, and the solution obtained in Step 2 as the electrolyte, electrocatalytic oxidation of 3,4-diaminofuran is carried out in the electrocatalytic system. During the electrocatalytic process, a second solution is added dropwise to the electrolyte. After the addition is completed, the mixture is stirred, centrifuged, washed, dried, and ground to obtain the final sample 3,3'-diamino-4,4'-azofuran. Step 5: Add Ce 3+ The electrolyte supernatant was oxidized and repaired to Ce using a 1.7 V DC power supply. 4+ This enables the recycling of oxidants.

[0027] Example 4 The preparation method of 3,3'-diamino-4,4'-azofuran through ion-coupled and electrochemical synergistic synthesis includes the following steps: In this embodiment, preferably, 3,4-diaminofuran and Ce 4+ The molar ratio is 1:2, and the acidic solution is a 1 mol / L sulfuric acid solution; Step 1: Cobalt nitrate hexahydrate, ammonium fluoride, urea and carbon are placed in a high-pressure reactor containing deionized water and hydrothermally heated to obtain carbon cloth loaded with Co3O4, namely CC-Co3O4. Step 2: Dissolve 1 mol / L of 3,4-diaminofuran in sulfuric acid solution with stirring to obtain the first solution; Step 3: Dissolve 2 mol / L cerium sulfate in a 1 mol / L sulfuric acid solution by stirring to obtain the second solution; Step 4: Using the material prepared in Step 1 as the anode, a platinum sheet as the counter electrode, and the solution obtained in Step 2 as the electrolyte, electrocatalytic oxidation of 3,4-diaminofuran is carried out in the electrocatalytic system. During the electrocatalytic process, a second solution is added dropwise to the electrolyte. After the addition is completed, the mixture is stirred, centrifuged, washed, dried, and ground to obtain the final sample 3,3'-diamino-4,4'-azofuran. Step 5: Add Ce 3+ The electrolyte supernatant was oxidized and repaired to Ce using a 1.9 V DC power supply. 4+ This enables the recycling of oxidants.

[0028] Example 5 The preparation method of 3,3'-diamino-4,4'-azofuran through ion-coupled and electrochemical synergistic synthesis includes the following steps: In this embodiment, preferably, 3,4-diaminofuran and Ce 4+ The molar ratio is 1:2.5, and the acidic solution is a 1 mol / L sulfuric acid solution; Step 1: Cobalt nitrate hexahydrate, ammonium fluoride, urea and carbon are placed in a high-pressure reactor containing deionized water and hydrothermally heated to obtain carbon cloth loaded with Co3O4, namely CC-Co3O4. Step 2: Dissolve 1 mol / L of 3,4-diaminofuran in sulfuric acid solution with stirring to obtain the first solution; Step 3: Dissolve 2.5 mol / L cerium sulfate in a 1 mol / L sulfuric acid solution by stirring to obtain the second solution; Step 4: Using the material prepared in Step 1 as the anode, a platinum sheet as the counter electrode, and the solution obtained in Step 2 as the electrolyte, electrocatalytic oxidation of 3,4-diaminofuran is carried out in the electrocatalytic system. During the electrocatalytic process, a second solution is added dropwise to the electrolyte. After the addition is completed, the mixture is stirred, centrifuged, washed, dried, and ground to obtain the final sample 3,3'-diamino-4,4'-azofuran. Step 5: Add Ce 3+ The electrolyte supernatant was oxidized and repaired to Ce using a 2.0 V DC power supply. 4+ This enables the recycling of oxidants.

[0029] Comparative Example 1 This comparative example is basically the same as Example 4, except that Ce is used. 4+ Replace with Fe 3+ The reaction was found to be unable to proceed, with no product formed. This is due to Fe 3+ Its oxidizing power is weaker than Ce. 4+ Comparative Example 2 This comparative example is basically the same as Example 4, except that the electrocatalytic working voltage is 0 V. A decrease in product yield was observed, indicating that at extremely low catalytic voltages, the anode can assist the oxidant Ce. 4+ To achieve electrocatalysis.

[0030] Comparative Example 3 This comparative example is basically the same as Example 4, except that the working voltage of the repair power supply is 0 V, and Ce was found to be present. 3+ It cannot be repaired.

[0031] The relevant process parameters and product yields of Examples 1-5 are shown in Table 1 below.

[0032] Table 1 shows the product yields in Examples 1-5. As shown in Table 1, the yield of azofuran increases with increasing cerium content. The yield reaches its maximum (85.8%) when the molar ratio of 3,4-diaminofuran to cerium is 1:2. However, the yield decreases with further increases in cerium content. This may be due to the influence of cerium... 4+ Excessive amounts lead to insufficient contact with the substrate. During Ce repair, the highest Ce repair efficiency is achieved at 1.9 V; above 1.9 V, side reactions occur in the solution, resulting in additional energy loss.

[0033] The 3,3'-diamino-4,4'-azofuran prepared in Example 4 was characterized as follows: Figure 1The Raman spectral density diagram of 3,3'-diamino-4,4'-azofuran obtained in Example 4 is shown. Two distinct characteristic peaks appear at wavenumbers of 1259 and 1430, which can be attributed to the NO bond and N=N bond vibrations of 3,3'-diamino-4,4'-azofuran. Figure 2 The 3,3'-diamino-4,4'-azofuran obtained in Example 4 13 The results of the C NMR test are as follows: Figure 3 As shown, characteristic peaks appear at δ = 151.19 and 156.15, corresponding to the tetrazolium carbon of 3,3'-diamino-4,4'-azofuran.

[0034] Figure 3 Ce obtained in Example 4 4+ The UV absorption spectrum of the repair solution. The results show that after repair with a DC power supply, Ce... 4+ The concentration increased significantly.

[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 the synergistic synthesis of 3,3'-diamino-4,4'-azofuran by ion-pair and electrochemical methods, characterized in that, Includes the following steps: Step 1: Preparation of CC-Co3O4: CC-Co3O4 is prepared by hydrothermal method using nitric acid hexahydrate, ammonium fluoride, urea and carbon cloth as raw materials. Step 2: Dissolve 3,4-diaminofuran in the first acidic solution to obtain the first solution; Step 3: Add Ce 4+ The salt dissolves in the second acidic solution to obtain the second solution; Step 4: Using CC-Co3O4 as the anode, a platinum sheet as the counter electrode, and the first solution as the electrolyte, an electrocatalytic oxidation reaction is carried out. During the electrocatalytic oxidation process, the second solution is added dropwise to the electrolyte. After the second solution is added, the mixture is stirred, centrifuged, washed, dried, and ground to obtain the 3,3'-diamino-4,4'-azofuran.

2. The method for the synergistic synthesis of 3,3'-diamino-4,4'-azofuran according to claim 1, characterized in that, In step one, the temperature of the hydrothermal reaction is maintained at 130-150℃ so that Co3O4 has a spinel structure.

3. The method for the synergistic synthesis of 3,3'-diamino-4,4'-azofuran according to claim 1, characterized in that, In step three, the Ce-containing 4+ The dissolution of a salt in a second acidic solution refers to the dissolution of cerium sulfate in a second acidic solution under stirring conditions, where Ce in the second acidic solution... 4+ The molar concentration is 0.5-2.5 mol / L.

4. The method for the synergistic synthesis of 3,3'-diamino-4,4'-azofuran according to claim 1 or 3, characterized in that, The second acidic solution and the first acidic solution are both selected from one or more of sulfuric acid, nitric acid or hydrochloric acid, and the second acidic solution and the first acidic solution have the same acid concentration.

5. The method for preparing 3,3'-diamino-4,4'-azofuran according to claim 1, characterized in that, In the fourth step, the centrifugation separation yields Ce-containing products. 3+ The electrolyte supernatant and the precipitate containing the target product are used; the washing, drying and grinding are performed on the precipitate, wherein the centrifugation speed is 5000~8000 rpm and the drying temperature is 40-50℃.

6. The method for preparing 3,3'-diamino-4,4'-azofuran according to claim 1, characterized in that, It also includes step five: [The text abruptly ends here, likely due to an incomplete sentence or a formatting error.] 3+ The electrolyte supernatant was oxidized and repaired to Ce using a DC power supply. 4+ Used in step three, Ce 4+ The raw materials.

7. The method for the synergistic synthesis of 3,3'-diamino-4,4'-azofuran according to claim 6, characterized in that, The Ce 3+ Oxidative repair to Ce 4+ The voltage of the DC power supply used is 1-2 V.

8. The method for the synergistic synthesis of 3,3'-diamino-4,4'-azofuran according to claim 1, characterized in that, The 3,4-diaminofuran and Ce 4+ The molar ratio is 1:0.5-1:2.

5.

9. The method for the synergistic synthesis of 3,3'-diamino-4,4'-azofuran according to claim 1, characterized in that, The voltage applied in the electrocatalytic oxidation reaction in step four is 1.2 V vs. RHE.

10. A 3,3-diamino-4,4-azofuran prepared using the method described in any one of claims 1 to 9.

Images