A method for preparing 5-aminotetrazole nitrate

Abstract

The application discloses a preparation method of pentaaminotetrazolium nitrate, wherein concentrated nitric acid is added dropwise into an alkali solution of pentaaminotetrazolium to generate an acid-base reaction under water bath condition, and the reaction is preserved for a certain time, and the target product can be prepared after cooling and washing. The application can increase the product yield to more than 90%, reduce the usage amount of nitric acid and the generation of waste liquid, and improve the purity of pentaaminotetrazolium nitrate, and can be used in civil explosives, propellants and gas generating agents.

Description

Technical Field

[0001] This invention belongs to the field of energetic compound preparation technology, specifically relating to a method for preparing pentaaminotetrazole nitrate. Background Technology

[0002] Tetraazole energetic compounds have received widespread attention due to their high nitrogen content and potential high energy. Among them, 5-aminotetrazole nitrate (CH4N6O3) has a nitrogen content of 56.75% and an oxygen balance of -10.8%, showing good potential as a gas-generating agent and propellant component. Furthermore, 5-aminotetrazole nitrate has a calculated detonation velocity as high as 8900 m / s, making it a potential alternative to civilian explosives.

[0003] Current reports on the synthesis process of 5-aminotetrazole nitrate all involve the direct reaction of 5-aminotetrazole (5-AT) with nitric acid at different temperatures. SP Burns et al. first reacted 5-AT with concentrated nitric acid (65%) in an ice-water bath for 1 hour, then added distilled water, boiled, and cooled to crystallize at room temperature (Burns SP, Khandhaya P S. Method of formulating agas generant composition: US, US6475312 B1[P].). Moritzvon et al. used the opposite method, mixing 5-AT with concentrated nitric acid (65%), reacting it first in a boiling water bath, and then crystallizing it in an ice-water bath (M Von Denffer, T). Kramer G, et al. Propellants Explosives Pyrotechnics, 2010, 30(3): 191-195.). Meng Lingqiao reacted 5-AT with concentrated nitric acid (65%) at 70-75℃ for 1.5 h, with a yield of 88.91% (Meng Lingqiao. Synthesis and Performance Study of Bis-tetrazole Hydrazine and Aminotetrazole Energetic Salts [D]. Beijing: Beijing Institute of Technology, 2010.). Ma Guixia et al. reacted in a 70℃ hot water bath for 1 h, with a yield of 65% (Ma GX, Zhang TL, Zhang HG, et al. Thermochimica Acta, 2004(1 / 2): 423.). The above methods have the problems of long reaction time, harsh reaction temperature, and low yield. Wang Mengmeng reported a yield of 92.6% by reacting nitric acid and 5-AT at a molar ratio of 4.5:1 at 20℃ for 20 min (Wang Mengmeng, Du Zhiming, Zhao Zhihua, et al. Energetic Materials, 2014(1):17-21). However, the above methods result in high impurity content in the product and problems with excessive use of acid. In summary, the existing reported methods are not suitable for industrial production, hindering the application of 5-aminotetrazole nitrate. Summary of the Invention

[0004] To address the problems of harsh reaction conditions, excessive waste of raw materials, and high levels of impurities in the product from existing methods, this invention aims to provide a green and recyclable method for preparing 5-aminotetrazole nitrate. This method, by introducing an alkaline solution to dissolve 5-AT and recycling the mother liquor, achieves a 5-aminotetrazole nitrate preparation process with high yield, low wastewater volume, and continuous recycling characteristics, providing a reliable process solution for the large-scale application of 5-aminotetrazole nitrate.

[0005] The technical solution to achieve the objective of this invention is: a method for preparing 5-aminotetrazole nitrate, specifically comprising the following steps:

[0006] Under water bath conditions, concentrated nitric acid is added dropwise to an alkaline solution of pentaaminotetrazole to induce an acid-base reaction. The reaction is maintained at this temperature for a certain period of time, followed by cooling and washing to prepare the target product.

[0007] Preferably, the alkali is any one of sodium hydroxide, potassium hydroxide, and ammonium hydroxide (ammonia water), with sodium hydroxide being the most preferred.

[0008] Preferably, the concentration of pentaaminotetrazole in the alkaline solution is 7.8 wt.% to 20.3 wt.%, more preferably 7.8 wt.% to 14.5 wt.%.

[0009] Preferably, in the alkaline solution of pentaaminotetrazole, the molar ratio of pentaaminotetrazole to alkali is 1:0.5 to 1.5, more preferably 1:0.5 to 1.0.

[0010] Preferably, the dropping time of concentrated nitric acid should not exceed 5 minutes.

[0011] Preferably, the acid-base reaction temperature is not higher than 80℃, and more preferably 25℃~45℃.

[0012] Preferably, the acid-base reaction time is 2 to 15 minutes, and more preferably 2 to 5 minutes.

[0013] Preferably, the reaction is carried out under stirring conditions.

[0014] Compared with the prior art, the present invention utilizes the increased solubility of pentaaminotetrazole in alkaline solution to transform the solid-liquid phase reaction in the prior art into a liquid-liquid phase reaction, thereby reducing the amount of nitric acid used and the generation of waste liquid, improving the purity and crystal quality of the product, and making it suitable for use in civilian explosives, propellants and gas-generating agents. Attached Figure Description

[0015] Figure 1 XRD patterns of 5-ATN prepared by literature method are compared with those of raw material 5-AT.

[0016] Figure 2The DSC curve of 5-ATN at 40℃ is shown.

[0017] Figure 3 The DSC curve of 5-ATN at 80℃ is shown.

[0018] Figure 4 Comparison of XRD patterns of 5-ATN prepared by the mother liquor method and the raw material 5-AT. Detailed Implementation

[0019] This invention discloses a process for preparing 5-aminotetrazole nitrate. It utilizes the increased solubility of pentaminotetrazole in an alkaline environment, differing from the solid-liquid phase reaction method in existing technologies by transforming the reaction into a liquid-liquid phase reaction to achieve the preparation of 5-aminotetrazole nitrate. Based on the characteristic that pentaminotetrazole has increased solubility in alkaline solutions, pentaminotetrazole is dissolved in an alkaline solution, and then concentrated nitric acid is added, thus transforming the solid-liquid phase reaction of the existing technology into a liquid-liquid phase reaction.

[0020] CH3N5+OH - +H + +NO3 - →CH3N5·HNO3+H2O

[0021] The following embodiments illustrate the invention in more detail, but are not intended to further limit the invention.

[0022] Case 1

[0023] Following the process described in the literature (Wang Mengmeng, Du Zhiming, Zhao Zhihua, et al. Energetic Materials, 2014(1):17-21.), 5g of 5-AT·H2O was reacted with 15mL of concentrated nitric acid (65wt.%) at 20℃ for 15min with stirring. The mixture was then filtered and washed with ethanol at 5-10℃.

[0024] according to Figure 1 The comparison of the given spectra shows that the 5-ATN prepared according to the literature method contains more impurities. The X-ray diffraction peaks of the prepared 5-ATN mostly overlap with those of the raw material 5-AT, indicating that it contains a large amount of impurities.

[0025] Case 2

[0026] 1.4 g (0.02 mol) of sodium hydroxide was dissolved in 20 ml of deionized water. A certain amount of pentaminotetrazole powder was added to the sodium hydroxide solution and stirred to dissolve. Under a 45°C water bath, 7.6 g (0.08 mol) of concentrated nitric acid was added dropwise to the 5-aminotetrazole sodium hydroxide solution. After the addition was complete, the reaction was maintained at this temperature for 2 minutes, followed immediately by cooling and crystallization. Finally, the product was filtered and washed with ethanol at 0-10°C to prevent the ethanol at room temperature from dissolving the product. Table 1 shows the yield comparison for different molar ratios of sodium hydroxide to pentaminotetrazole.

[0027] Table 1

[0028]

[0029] The above implementation examples demonstrate that when n(NaOH):n(5-AT) = 1:1.5, the yield is 67%, which is the highest among the control experiments.

[0030] Case 3

[0031] 0.02 mol of an alkaline substance was dissolved in 20 ml of deionized water. 2.55 g of 0.03 mol of pentaminotetrazole powder was added to the alkaline solution and stirred until dissolved. Under a 45°C water bath, 4.75 g (0.05 mol) of concentrated nitric acid was added dropwise to the 5-aminotetrazole alkaline solution. After the addition was complete, the reaction was maintained at this temperature for 2 minutes, followed immediately by cooling and crystallization. Finally, the product was filtered and washed with ethanol at 0–10°C to prevent dissolution of the product by ethanol at room temperature. Table 2 shows the yield comparison for different types of alkaline substances.

[0032] Table 2

[0033]

[0034] The above implementation cases demonstrate that when using three alkaline solutions as comparisons, the change in yield is not significant, indicating that the three alkaline solutions have little impact on the yield. However, considering the actual production cost, choosing the cheaper sodium hydroxide is more reasonable.

[0035] Case 4

[0036] 1.4 g (0.02 mol) of sodium hydroxide was dissolved in 20 ml of deionized water. 3.5 g (0.03 mol) of pentaminotetrazole powder was added to the sodium hydroxide solution and stirred until dissolved. Under a water bath at 40–80 °C, 4.75 g of concentrated nitric acid was added dropwise to the 5-aminotetrazole sodium hydroxide solution. After the addition was complete, the reaction was maintained at this temperature for 2 minutes, followed immediately by cooling and crystallization. Finally, the product was filtered and washed with ethanol at 0–10 °C to prevent dissolution of the product by ethanol at room temperature. Table 3 shows the yield comparison at different water bath temperatures (reaction temperatures).

[0037] Table 3

[0038]

[0039] The final comparative case revealed that the yield decreased continuously when the reaction temperature exceeded 40°C, so a lower temperature was actually more conducive to increasing the yield.

[0040] In addition, through Figure 2 and Figure 3 The given differential scanning calorimetry (DSC) data indicates that the product prepared at 40°C ( Figure 2 The product prepared at 80℃ exhibits only one distinct exothermic peak, which is quite sharp. Figure 3 Before the exothermic peak appears, there is a small endothermic peak, and the width of the exothermic peak is significantly larger than that of the product prepared at room temperature, which to some extent proves that the product prepared at room temperature is better and has higher purity.

[0041] Case 5

[0042] 1.4 g (0.02 mol) of sodium hydroxide was dissolved in 20 ml of deionized water. 3.5 g (0.03 mol) of pentaminotetrazole powder was added to the sodium hydroxide solution and stirred until dissolved. Under a 45°C water bath, 4.75 g of concentrated nitric acid was added dropwise to the 5-aminotetrazole sodium hydroxide solution. After the addition was complete, the reaction was maintained at this temperature for a certain time, followed immediately by cooling and crystallization. Finally, the product was filtered and washed with ethanol at 0-10°C to prevent dissolution of the product by ethanol at room temperature. Table 4 shows the yield comparison for different reaction times.

[0043] Table 4

[0044]

[0045]

[0046] The final comparative case demonstrates that while increasing the amount of nitric acid can improve the yield, it does so beyond a certain range.

[0047] Case 6

[0048] First, 1.4 g (0.02 mol) of sodium hydroxide was dissolved in 20 ml of deionized water. Then, 3.5 g (0.03 mol) of pentaminotetrazole powder was added to the sodium hydroxide solution and stirred to dissolve. Under a 45°C water bath, 6.0 g of concentrated nitric acid was added dropwise to the 5-aminotetrazole sodium hydroxide solution. After the addition was complete, the reaction was maintained at this temperature for 2 minutes, followed immediately by cooling and crystallization. Finally, the product was filtered and washed with ethanol at 0-10°C to prevent the ethanol at room temperature from dissolving the product. Table 5 shows the yield comparison for different nitric acid contents.

[0049] Table 5

[0050]

[0051] The final comparative case revealed that the highest yield was achieved when the ratio of nitric acid to the total amount of sodium hydroxide and pentaaminotetrazole was 1.2:1.

[0052] Case 7

[0053] 1.4 g of sodium hydroxide was added to the collected mother liquor, followed by 3.5 g of 5-AT·H₂O dissolved in the mother liquor. Under ambient temperature water bath conditions, 6.0 g of concentrated nitric acid (65% by mass) was added dropwise to the 5-aminotetrazole sodium hydroxide solution over 5 minutes. The mixture was stirred and kept at this temperature for 2 minutes, followed immediately by cooling and crystallization. Finally, the mixture was filtered and the mother liquor was collected. The product was washed with ethanol at 0-10°C to prevent dissolution of the product by ethanol at room temperature. The above steps were repeated 6 times. Table 6 shows the yield comparison under different mother liquor recycling numbers.

[0054] Table 6

[0055]

[0056] The experimental group showed that mother liquor recycling not only reduced the amount of wastewater to be treated, but also increased the yield to over 94%.

[0057] pass Figure 4 The comparison of the X-ray diffraction patterns showed that the intensity of the characteristic diffraction peaks of 5-ATN was significantly higher than that of 5-AT, and the positions of the diffraction peaks were different, proving that the target product was 5-ATN.

Claims

1. A process for the preparation of 5-amino tetrazolium nitrate, characterized in that, Specifically comprising the following steps: Under water bath condition, concentrated nitric acid is added dropwise into the alkaline solution of pentaamino tetrazole to generate acid-base reaction and keep reaction for a certain time, and the target product can be prepared after cooling and washing; The base is sodium hydroxide; The concentration of pentaamino tetrazole in the alkaline solution is 7.8wt.% ~20.3wt.%. The molar ratio of pentaamino tetrazole to the base is 1: 0.5~1.

5. The dropwise adding time of concentrated nitric acid is not more than 5min.

2. The method of claim 1, wherein, The concentration of pentaamino tetrazole in the alkaline solution is 7.8wt.% ~14.5 wt.%.

3. The method of claim 1, wherein, The molar ratio of pentaamino tetrazole to the base is 1: 0.5~1.

0.

4. The method of claim 1, wherein, The acid-base reaction temperature is not higher than 80℃.

5. The method of claim 1, wherein, The acid-base reaction temperature is room temperature ~45℃.

6. The method of claim 1, wherein, The acid-base reaction time is 2~15min.

7. The method of claim 1, wherein, The acid-base reaction time is 2~5min.

8. The method of claim 1, wherein, The reaction is carried out under stirring condition.

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