Synthesis method of 5-nitrotetrazole sodium salt

Abstract

The invention discloses a synthesis method of 5-nitrotetrazole sodium salt, and solves the problem of relatively large potential safety hazard in the synthesis process of 5-nitrotetrazole sodium in the prior art. The method for safely preparing the high-energy compound 5-nitrotetrazole sodium salt based on DAT comprises the following steps: adding 1, 5-diamino tetrazole into a certain amount of ice water and acid to dissolve 1, 5-diamino tetrazole; slowly dropwise adding a sodium nitrite solution into the ice-water mixture solution, and uniformly stirring at a certain temperature; slowly heating the mixture to a certain temperature, and reacting for a period of time to obtain filtrate; removing filtrate to obtain white powder; and dissolving the obtained white powder in acetone, filtering to obtain a solution, and removing the solvent to obtain the 5-nitrotetrazole sodium salt. The preparation method provided by the invention is simple, safe and mild in reaction condition; water is used as a solvent, so that environmental pollution is avoided, and environmental protection requirements are completely met; and dangerous intermediates such as tetrazole-5 diazonium salt and 5nitrotetrazole acid copper salt are not generated.

Description

Technical Field

[0001] The invention relates to the technical field of energetic materials, and in particular to a method for synthesizing 5-nitrotetrazole sodium salt. Background Art

[0002] A detonator is an explosive that can explode under the action of weak external excitation energy (such as mechanical, thermal, electrical, and optical). It can transform from combustion to detonation in a very short time (a few microseconds), and has the characteristics of high sensitivity and short detonation growth period. Lead azide (LA) and lead styphnate (LTNR) have been used as detonators for nearly a hundred years, and they are very common in the field of military pyrotechnics. However, LA is easily exploded by mechanical stimulation, and LTNR is extremely sensitive to static sparks, which limits their safety. At the same time, lead-containing detonators may cause damage to human health and pollute the environment during manufacturing and use. Therefore, countries are actively developing new green detonators that can replace LA and LTNR. These new detonators mainly include triazoles, tetrazoles, tetrazines, and chain polynitrogen complexes, etc., which aim to provide safer and more environmentally friendly explosive materials. Tetrazole is a five-membered heterocyclic unsaturated compound composed of four nitrogen atoms. It has a planar ring skeleton structure and aromaticity. Its nitrogen content is as high as 80%, which is the five-membered heterocyclic compound with the highest nitrogen content except for all-nitrogen compounds. Tetrazole compounds have high nitrogen content and compact structure, and the final product of their combustion or explosion is mainly nitrogen (N2), which not only helps to avoid environmental pollution and health risks, but also reduces tail smoke signals. It can be used as a potential energetic material in high-efficiency non-toxic gas generators and low-signature signal propellants. After years of efforts by scientists from various countries, 5-nitrotetrazole cuprous (DBX-1) was prepared. Its comprehensive performance (ignition sensitivity, detonation ability, temperature resistance, etc.) is comparable to LA, and it is considered to be the most likely green detonator to replace LA. However, there are major safety hazards in the synthesis process of 5-nitrotetrazole sodium (5-NaNT), the raw material of DBX-1.

[0003] In 1937, Edmund et al. used 5-aminotetrazole as raw material, and successively carried out diazotization reaction, substitution reaction and hydrolysis reaction to obtain 5-NaNT solution, and then concentrated and crystallized the solution to finally obtain solid 5-NaNT solid. This synthesis method will cause continuous micro-explosions during the diazotization process, which will damage the glass reactor in severe cases, resulting in high risk of preparing 5-nitrotetrazole derivatives, low yield, and complex production process, which is not conducive to mass production. In 2009, et al. introduced a divalent copper salt during the diazotization reaction to generate 5-nitrotetrazolyl acid copper salt, then filtered the acid copper salt, transferred the filter cake to water, oxidized the copper ions to copper oxide using a sodium hydroxide solution under heating conditions, filtered and removed the copper oxide to obtain a 5-NaNT solution; after the solution was concentrated and cooled and crystallized, solid 5-NaNT was obtained, and the reaction process was as follows. The disadvantage of this synthesis method is that the sensitive 5-nitrotetrazolyl acid copper salt intermediate needs to be manually handled, which is dangerous; in addition, 5-NaNT is very soluble in water, the synthesis yield is low, and the 5-NaNT solid obtained by cooling and crystallization contains more impurities (sodium nitrate, sodium nitrite, tetrazole, tetrazolyl, etc.).

[0004] Summary of the invention

[0005] The purpose of the present invention is to provide a method for synthesizing 5-nitrotetrazole sodium salt, so as to solve the technical problem that there are great potential safety hazards in the synthesis process of 5-nitrotetrazole sodium salt in the prior art.

[0006] To achieve the above object, the present invention provides the following technical solution: based on DAT, a high-energy compound 5-nitrotetrazole sodium salt is safely prepared, and its synthesis route is as follows:

[0007]

[0008] The present invention provides a method for synthesizing 5-nitrotetrazole sodium salt, comprising the following steps:

[0009] Step 1: Add a certain amount of ice water and acid to dissolve 1,5-diaminotetrazole;

[0010] Step 2, slowly adding the sodium nitrite solution dropwise to the ice-water mixture solution obtained in step 1, and stirring evenly at a certain temperature;

[0011] Step 3, slowly raising the mixture obtained in step 2 to a certain temperature, reacting for a period of time, and obtaining a filtrate;

[0012] Step 4, removing the filtrate to obtain a white powder;

[0013] Step 5: dissolving the obtained white powder in acetone, filtering the obtained solution, and removing the solvent to obtain 5-nitrotetrazole sodium salt.

[0014] Furthermore, the 1,5-diaminotetrazole is synthesized by the following route:

[0015]

[0016] Furthermore, the synthesis route of the 1,5-diaminotetrazole (DAT) is as follows: 1,3-diaminoguanidine hydrochloride is added to 0.1M dilute hydrochloric acid, and a saturated sodium nitrite solution is added dropwise at low temperature. After the addition is completed, the reaction is continued for 0.5h. After the reaction is completed, the pH is adjusted to 8 with anhydrous sodium carbonate, the temperature is raised to 40°C, and the reaction is continued for 0.5h. Part of the water is distilled off under reduced pressure at 40°C, and the mixture is placed in a refrigerator for crystallization while hot, filtered, and then recrystallized with ethanol to obtain DAT with higher purity.

[0017] Furthermore, in the step 1, the molar ratio of 1,5-diaminotetrazole to the acid is 1:3-8, and the acid includes hydrochloric acid, sulfuric acid, and dilute tetrafluoroboric acid.

[0018] Furthermore, the sodium nitrite solution in step 2 is a saturated aqueous solution of sodium nitrite, and the molar ratio of the 1,5-diaminotetrazole to the sodium nitrite solution is 1:10-20.

[0019] Furthermore, the method further comprises step 6, recrystallizing the white solid in step 5 in acetone and dichloromethane to obtain high-purity 5-nitrotetrazole sodium salt.

[0020] Based on the above technical solution, the embodiments of the present invention can at least produce the following technical effects:

[0021] The preparation method provided by the invention is simple, safe and has mild reaction conditions; water is used as a solvent, which is pollution-free to the environment and fully meets environmental protection requirements; and no dangerous intermediates such as tetrazole-5-diazonium salt and 5-nitrotetrazolyl acid copper salt are generated. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0023] Figure 1 It is the high-energy compound 5-nitrotetrazole sodium salt in Example 1. DETAILED DESCRIPTION

[0024] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0025] It should be understood that the terms described in the present invention are only for describing special embodiments and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0026] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0027] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to the skilled artisan. The present invention description and examples are exemplary only.

[0028] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0029] Example 1

[0030] Add a small amount of ice and 4mmol of dilute sulfuric acid to 1mmol of DAT, wait until it is completely dissolved, add ice, place in a 0℃ reaction bath, slowly drop 10mmol of a saturated aqueous solution of sodium nitrite into the DAT solution (always keep ice in the solution), continue to react at low temperature for 0.5h after the addition is complete. Then slowly heat to room temperature and react for 1h. After the reaction is complete, remove the solvent to obtain white crystals. Dissolve the obtained white powder in acetone, filter to obtain a solution, remove the solvent, and dry. The yield is 62.54%.

[0031] Experimental Example 2

[0032] Add a small amount of ice and 3mmol of dilute sulfuric acid to 1mmol of DAT, wait until it is completely dissolved, add ice, place in a 0℃ reaction bath, slowly drop 10mmol of a saturated aqueous solution of sodium nitrite into the DAT solution (always keep ice in the solution), continue to react at low temperature for 0.5h after the addition is complete. Then slowly heat to room temperature and react for 1h. After the reaction is complete, remove the solvent to obtain white crystals. Dissolve the obtained white powder in acetone, filter to obtain a solution, remove the solvent, and dry. The yield is 58.46%.

[0033] Experimental Example 3

[0034] Add a small amount of ice and 4mmol of dilute sulfuric acid to 1mmol of DAT, wait until it is completely dissolved, add ice, place in a 0℃ reaction bath, slowly drop 20mmol of a saturated aqueous solution of sodium nitrite into the DAT solution (always keep ice in the solution), continue to react at low temperature for 0.5h after the addition is complete. Then slowly heat to room temperature and react for 1h. After the reaction is complete, remove the solvent to obtain white crystals. Dissolve the obtained white powder in acetone, filter to obtain a solution, remove the solvent, and dry. The yield is 48.91%.

[0035] Experimental Example 4

[0036] Add a small amount of ice and 8mmol of dilute hydrochloric acid to 1mmol of DAT, wait until it is completely dissolved, add ice, place in a 0℃ reaction bath, slowly drop 10mmol of a saturated aqueous solution of sodium nitrite into the DAT solution (always keep ice in the solution), continue to react at low temperature for 0.5h after the addition is complete. Then slowly heat to room temperature and react for 1h. After the reaction is complete, remove the solvent to obtain white crystals. Dissolve the obtained white powder in acetone, filter to obtain a solution, remove the solvent, and dry. The yield is 46.45%.

[0037] Experimental Example 5

[0038] Add a small amount of ice and 8mmol of dilute hydrochloric acid to 1mmol of DAT, wait until it is completely dissolved, add ice, place in a 0℃ reaction bath, slowly drop 20mmol of a saturated aqueous solution of sodium nitrite into the DAT solution (always keep ice in the solution), continue to react at low temperature for 0.5h after the addition is complete. Then slowly heat to room temperature and react for 1h. After the reaction is complete, remove the solvent to obtain white crystals. Dissolve the obtained white powder in acetone, filter to obtain a solution, remove the solvent, and dry. The yield is 41.77%.

[0039] Experimental Example 6

[0040] Add a small amount of ice and 6mmol of dilute hydrochloric acid to 1mmol of DAT, wait until it is completely dissolved, add ice, place in a 0℃ reaction bath, slowly drop 10mmol of a saturated aqueous solution of sodium nitrite into the DAT solution (always keep ice in the solution), continue to react at low temperature for 0.5h after the addition is complete. Then slowly heat to room temperature and react for 1h. After the reaction is complete, remove the solvent to obtain white crystals. Dissolve the obtained white powder in acetone, filter to obtain a solution, remove the solvent, and dry. The yield is 42.83%.

[0041] Experimental Example 7

[0042] Add a small amount of ice and 6mmol of dilute hydrochloric acid to 1mmol of DAT, wait until it is completely dissolved, add ice, place in a 0℃ reaction bath, slowly drop 20mmol of a saturated aqueous solution of sodium nitrite into the DAT solution (always keep ice in the solution), continue to react at low temperature for 0.5h after the addition is complete. Then slowly heat to room temperature and react for 1h. After the reaction is complete, remove the solvent to obtain white crystals. Dissolve the obtained white powder in acetone, filter to obtain a solution, remove the solvent, and dry. The yield is 39.95%.

[0043] Experimental Example 8

[0044] Add a small amount of ice and 8 mmol of dilute tetrafluoroboric acid to 1 mmol of DAT, wait until it is completely dissolved, add ice, place in a 0°C reaction bath, slowly drop 10 mmol of a saturated aqueous solution of sodium nitrite into the DAT solution (always keep ice in the solution), continue to react at low temperature for 0.5 h after the addition is complete. Then slowly heat to room temperature and react for 1 h. After the reaction is complete, remove the solvent to obtain white crystals. Dissolve the obtained white powder in acetone, filter to obtain a solution, remove the solvent, and dry. The yield is 68.02%.

[0045] Experimental Example 9

[0046] Add a small amount of ice and 6 mmol of dilute tetrafluoroboric acid to 1 mmol of DAT, wait until it is completely dissolved, add ice, place in a 0°C reaction bath, slowly drop 10 mmol of a saturated aqueous solution of sodium nitrite into the DAT solution (always keep ice in the solution), continue to react at low temperature for 0.5 hours after the addition is complete. Then slowly heat to room temperature and react for 1 hour. After the reaction is complete, remove the solvent to obtain white crystals. Dissolve the obtained white powder in acetone, filter to obtain a solution, remove the solvent, and dry. The yield is 64.60%.

[0047] Experimental Example 10

[0048] Add a small amount of ice and 6 mmol of dilute tetrafluoroboric acid to 1 mmol of DAT, wait until it is completely dissolved, add ice, place in a 0°C reaction bath, slowly drop 20 mmol of a saturated aqueous solution of sodium nitrite into the DAT solution (always keep ice in the solution), continue to react at low temperature for 0.5 hours after the addition is complete. Then slowly heat to room temperature and react for 1 hour. After the reaction is complete, remove the solvent to obtain white crystals. Dissolve the obtained white powder in acetone, filter to obtain a solution, remove the solvent, and dry. The yield is 60.18%.

[0049] Experimental Example 11

[0050] Add a small amount of ice and 8 mmol of dilute tetrafluoroboric acid to 1 mmol of DAT, wait until it is completely dissolved, add ice, place in a 0°C reaction bath, slowly drop 20 mmol of a saturated aqueous solution of sodium nitrite into the DAT solution (always keep ice in the solution), continue to react at low temperature for 0.5 h after the addition is complete. Then slowly heat to room temperature and react for 1 h. After the reaction is complete, remove the solvent to obtain white crystals. Dissolve the obtained white powder in acetone, filter to obtain a solution, remove the solvent, and dry. The yield is 62.75%.

[0051] The structure of the 5-nitrotetrazole sodium salt obtained in Experimental Example 1 was identified. Figure 1 As shown, the results are as follows:

[0052] Infrared (KBr, cm-1): 3417, 2862, 2732, 2468, 2099, 1690, 1548, 1508, 1474, 1454, 1421, 1376, 1321, 1193, 1172, 1066, 1041, 841, 665, 602, 539;

[0053] 13C NMR (DMSO, δ, ppm): 169.2;

[0054] Elemental analysis: CH4N5NaO4

[0055] Theoretical value: C (6.94%), H (2.33%), N (40.47%);

[0056] Found values: C (6.81%), H (2.17%), N (40.68%).

[0057] Finally, it should be noted that:

[0058] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions described in the above embodiments may still be modified, or some or all of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for synthesizing 5-nitrotetrazole sodium salt, characterized in that: The steps include: Step 1: Add a certain amount of ice water and acid to dissolve 1,5-diaminotetrazole; Step 2, slowly adding the sodium nitrite solution dropwise to the ice-water mixture solution obtained in step 1, and stirring evenly at a certain temperature; Step 3, slowly raising the mixture obtained in step 2 to a certain temperature, reacting for a period of time, and obtaining a filtrate; Step 4, removing the filtrate to obtain a white powder; Step 5: dissolving the obtained white powder in acetone, filtering the obtained solution, and removing the solvent to obtain 5-nitrotetrazole sodium salt.

2. The method for synthesizing 5-nitrotetrazole sodium salt according to claim 1, characterized in that: The 1,5-diaminotetrazole is synthesized by the following route:

3. The method for synthesizing 5-nitrotetrazole sodium salt according to claim 1, characterized in that: In the step 1, the molar ratio of 1,5-diaminotetrazole to the acid is 1:3-8, and the acid includes hydrochloric acid, sulfuric acid, and dilute tetrafluoroboric acid.

4. The method for synthesizing 5-nitrotetrazole sodium salt according to claim 1, characterized in that: The sodium nitrite solution in step 2 is a saturated aqueous solution of sodium nitrite, and the molar ratio of the 1,5-diaminotetrazole to the sodium nitrite solution is 1:10-20.

5. The method for synthesizing 5-nitrotetrazole sodium salt according to claim 1, characterized in that: The method further comprises step 6, wherein the white solid obtained in step 5 is recrystallized in acetone and dichloromethane to obtain high-purity 5-nitrotetrazole sodium salt.

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