Preparation method of 5-aminotetrazole nitrate

Abstract

The invention discloses a preparation method of pentaaminotetrazole nitrate, which comprises the following steps: under a water bath condition, dropwise adding concentrated nitric acid into an alkaline solution of pentaaminotetrazole to carry out acid-base reaction, keeping the temperature to react for a certain time, cooling and washing to prepare a target product. According to the method, the product yield can be increased to 90% or above, the use amount of nitric acid and generation of waste liquid are reduced, the purity of the pentaaminotetrazole nitrate is improved, and the pentaaminotetrazole nitrate can be applied to civil explosives, propellants and gas generating agents.

Description

Technical Field

[0001] The invention belongs to the field of energetic compound preparation technology, and specifically relates to a method for preparing pentaaminotetrazole nitrate. Background Art

[0002] Tetrazole energetic compounds have received extensive 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%. It has good application prospects as a gas generator and propellant component. In addition, 5-aminotetrazole nitrate has a calculated detonation velocity of up to 8900m / s, making it a potential substitute for civilian explosives.

[0003] At present, all reports on the synthesis process of 5-aminotetrazole nitrate are that 5-aminotetrazole (5-AT) is directly reacted 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, added distilled water and boiled, and cooled and crystallized at room temperature (Burns SP, Khandhadia P S. Method of formulating agas generant composition: US, US6475312 B1 [P].) Moritzvon et al. used the opposite method, mixing 5-ATAT with concentrated nitric acid (65%), first reacting in a boiling water bath, and then crystallizing 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°C for 1.5 hours, and the yield was 88.91% (Meng Lingqiao. Synthesis and Performance Research of Bis-tetrazolyl Hydrazine and Aminotetrazolyl Energetic Salts [D]. Beijing: Beijing Institute of Technology, 2010.). Ma Guixia et al. reacted in a hot water bath at 70°C for 1 hour, and the yield was 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 used nitric acid and 5-AT at a molar ratio of 4.5:1 at 20°C for 20 minutes, and reported a yield of 92.6% (Wang Mengmeng, Du Zhiming, Zhao Zhihua, et al. Energetic Materials, 2014 (1): 17-21.). However, the above method has problems such as high impurity content in the product and excessive use of acid. In summary, the existing reported methods are not suitable for industrial production, which hinders the application of 5-aminotetrazole nitrate. Summary of the invention

[0004] In order to solve the problems of harsh reaction conditions, excessive waste of raw materials, and relatively more raw material impurities in the product in the existing methods, the object of the present invention is to provide a green and recyclable method for preparing 5-aminotetrazole nitrate. The method realizes a 5-aminotetrazole nitrate preparation process with high yield, low wastewater volume and continuous circulation characteristics by introducing an alkaline solution to dissolve 5-AT and a mother liquor circulation method, and provides a reliable process scheme for the large-scale application of 5-aminotetrazole nitrate.

[0005] The technical solution to achieve the purpose of the present invention is: a method for preparing 5-aminotetrazole nitrate, which specifically comprises the following steps:

[0006] Under water bath conditions, concentrated nitric acid is added dropwise to an alkaline solution of pentaaminotetrazole to produce an acid-base reaction and the reaction is kept warm for a certain period of time, and then cooled and washed to prepare the target product.

[0007] Preferably, the base is any one of sodium hydroxide, potassium hydroxide and ammonium hydroxide (aqueous ammonia), preferably sodium hydroxide.

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

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

[0010] Preferably, the addition time of concentrated nitric acid is no more than 5 minutes.

[0011] Preferably, the acid-base reaction temperature is not higher than 80°C, preferably 25°C to 45°C.

[0012] Preferably, the acid-base reaction time is 2 to 15 minutes, 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 characteristic of increased solubility of pentaaminotetrazole in alkaline solution to convert 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 can be used in civilian explosives, propellants and gas generating agents. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a comparison of the XRD patterns of 5-ATN prepared by the literature method and the raw material 5-AT.

[0016] Figure 2This is the DSC curve of 5-ATN at 40°C.

[0017] Figure 3 This is the DSC curve of 5-ATN at 80°C.

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

[0019] The invention discloses a process for preparing 5-aminotetrazole nitrate, which utilizes a method for increasing the solubility of pentaaminotetrazole in an alkaline environment, and transforms the reaction into a liquid-liquid phase reaction, which is different from the solid-liquid phase reaction in the prior art, to achieve the preparation of 5-aminotetrazole nitrate. Based on the characteristic that the solubility of pentaaminotetrazole increases in an alkaline solution, pentaaminotetrazole is dissolved in an alkaline solution, and then concentrated nitric acid is added to transform the solid-liquid phase reaction in the prior art into a liquid-liquid phase reaction.

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

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

[0022] Case 1

[0023] According to the literature process (Wang Mengmeng, Du Zhiming, Zhao Zhihua, et al. Energetic Materials, 2014(1):17-21), 5g 5-AT·H2O and 15mL concentrated nitric acid (65wt.%) were reacted with stirring at 20°C for 15min, then filtered and the target product was washed with 5-10°C ethanol.

[0024] according to Figure 1 The comparison of the given spectra shows that the 5-ATN prepared according to the literature method has a high impurity content, and the X-ray diffraction peaks of the prepared 5-ATN overlap with those of the raw material 5-AT, indicating that the impurity content is relatively high.

[0025] Case 2

[0026] Dissolve 1.4g (0.02mol) of sodium hydroxide in 20ml of deionized water. Add a certain amount of pentaaminotetrazole powder to the sodium hydroxide solution and stir to dissolve. In a 45°C water bath, drop 7.6g (0.08mol) of concentrated nitric acid into the sodium hydroxide solution of 5-aminotetrazole. After the addition is complete, keep the reaction warm for 2 minutes, and then cool and crystallize immediately. Finally, filter and wash the product. When washing the product, wash it with 0-10°C ethanol to prevent ethanol from dissolving the product at room temperature. Table 1 shows the yield comparison under different molar ratios of sodium hydroxide and pentaaminotetrazole.

[0027] Table 1

[0028]

[0029] The above implementation case proves that when n(NaOH):n(5-AT)=1:1.5, the yield is 67%, which is the highest in the above control experiment.

[0030] Case 3

[0031] Dissolve 0.02 mol of alkaline substance in 20 ml of deionized water. Add 2.55 g of pentaaminotetrazole (0.03 mol) powder to the alkali solution and stir to dissolve. In a 45°C water bath, drop 4.75 g (0.05 mol) of concentrated nitric acid into the alkali solution of 5-aminotetrazole. After the addition is completed, keep the reaction warm for 2 minutes, and then cool and crystallize immediately. Finally, filter and wash. When washing the product, use 0-10°C ethanol to wash it to prevent ethanol from dissolving the product at room temperature. Table 2 shows the yield comparison under different types of alkaline substances.

[0032] Table 2

[0033]

[0034] The above implementation cases prove that when three alkaline solutions are used as comparison, the change in yield is not obvious, indicating that the above three alkaline solutions have little effect on the yield. However, considering the actual production cost, it is more reasonable to choose cheaper sodium hydroxide.

[0035] Case 4

[0036] Dissolve 1.4g (0.02mol) of sodium hydroxide in 20ml of deionized water. Add 3.5g (0.03mol) of pentaaminotetrazole powder to the sodium hydroxide solution and stir to dissolve. In a 40-80℃ water bath, drop 4.75g of concentrated nitric acid into the sodium hydroxide solution of 5-aminotetrazole. After the addition is complete, keep the reaction warm for 2min, and then cool and crystallize immediately. Finally, filter and wash the product. When washing the product, use 0-10℃ ethanol to wash it to prevent the ethanol from dissolving the product at room temperature. Table 3 shows the yield comparison under different water bath temperatures (reaction temperatures).

[0037] Table 3

[0038]

[0039] Through the final comparative case, it was found that when the reaction temperature exceeded 40°C, the yield continued to decrease, so a lower temperature was actually beneficial to increasing the yield.

[0040] In addition, through Figure 2 and Figure 3 The differential scanning calorimetry (DSC) results show that the product prepared at 40 °C ( Figure 2 ) has only one obvious exothermic peak, and the exothermic peak is relatively sharp. However, the product prepared at 80℃ ( Figure 3 ), there will be a small endothermic peak before the exothermic peak appears, and the width of the exothermic peak is significantly larger than that of the product under normal temperature conditions, which to a certain extent proves that the product prepared at room temperature is better and has higher purity.

[0041] Case 5

[0042] Dissolve 1.4g (0.02mol) of sodium hydroxide in 20ml of deionized water. Add 3.5g (0.03mol) of pentaaminotetrazole powder to the sodium hydroxide solution and stir to dissolve. In a 45°C water bath, drop 4.75g of concentrated nitric acid into the sodium hydroxide solution of 5-aminotetrazole. After the addition is complete, keep the reaction warm for a certain period of time, and then cool and crystallize immediately. Finally, filter and wash the product. When washing the product, wash it with 0-10°C ethanol to prevent the ethanol from dissolving the product at room temperature. Table 4 shows the yield comparison under different insulation reaction times.

[0043] Table 4

[0044]

[0045]

[0046] The final comparative case proves that increasing the amount of nitric acid can increase the yield, but it exceeds a certain range.

[0047] Case 6

[0048] First, 1.4g (0.02mol) of sodium hydroxide was dissolved in 20ml of deionized water. Then, 3.5g (0.03mol) of pentaaminotetrazole powder was added to the sodium hydroxide solution and stirred to dissolve. Under a 45°C water bath, 6.0g of concentrated nitric acid was added dropwise to the sodium hydroxide solution of 5-aminotetrazole. After the addition was completed, the reaction was kept warm for 2min and then cooled and crystallized immediately. Finally, suction filtration and washing were performed. When washing the product, 0-10°C ethanol was used to wash it to prevent the ethanol from dissolving the product at room temperature. Table 5 shows the yield comparison under different nitric acid contents.

[0049] Table 5

[0050]

[0051] Through the final comparative case, it was found that the highest yield was achieved when the ratio of the amount of nitric acid to the sum of sodium hydroxide and pentaaminotetrazole was 1.2:1.

[0052] Case 7

[0053] 1.4g of sodium hydroxide was added to the collected mother liquor, and then 3.5g of 5-AT·H2O was added to the mother liquor. Under normal temperature water bath conditions, 6.0g of concentrated nitric acid (mass fraction of 65%) was added dropwise to the sodium hydroxide solution of 5-aminotetrazole for 5min, stirred and kept warm for 2min, and cooled and crystallized immediately. Finally, suction filtration and mother liquor collection were performed, and the product was washed with 0-10°C ethanol to prevent ethanol from dissolving the product at room temperature. According to the above steps, the experiment was repeated 6 times, and Table 6 shows the yield comparison under different mother liquor cycle times.

[0054] Table 6

[0055]

[0056] Through the experimental group set up, it was found that the mother liquor circulation not only reduced the amount of wastewater treatment, but also increased the yield to more than 94%.

[0057] pass Figure 4 The X-ray diffraction patterns were compared, and the results showed that the characteristic peak diffraction peak intensity of 5-ATN was much 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 method for preparing 5-aminotetrazole nitrate, characterized in that: The specific steps include: Under water bath conditions, concentrated nitric acid is added dropwise to an alkaline solution of pentaaminotetrazole to produce an acid-base reaction, which is then kept warm for a certain period of time. The target product can then be prepared by cooling and washing.

2. The method according to claim 1, wherein The alkali is any one of sodium hydroxide, potassium hydroxide and ammonia water, preferably sodium hydroxide.

3. The method according to claim 1, wherein The concentration of pentaaminotetrazole in the alkaline solution is 7.8 wt.% to 20.3 wt.%, preferably 7.8 wt.% to 14.5 wt.%.

4. The method according to claim 1, wherein In the alkaline solution of pentaaminotetrazole, the molar ratio of pentaaminotetrazole to the base is 1: 0.5 to 1.5, preferably 1: 0.5 to 1.

0.

5. The method according to claim 1, wherein The addition time of concentrated nitric acid should not exceed 5 minutes.

6. The method according to claim 1, wherein The acid-base reaction temperature is not higher than 80°C, preferably room temperature to 45°C.

7. The method according to claim 1, wherein The acid-base reaction time is 2 to 15 minutes, preferably 2 to 5 minutes.

8. The method according to claim 1, wherein The reaction is carried out under stirring conditions.

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