A heat-resistant fluorescent active energetic compound and its synthesis method

Abstract

The invention discloses a heat-resistant fluorescent active energetic compound and a synthesis method thereof, wherein 2-(amino(4-amino-1,2,5-oxadiazole-3-yl)methylene)malononitrile is used as a raw material, and then subjected to cycloaddition with sodium azide and further cyclization to obtain 6-(1 H ‑tetrazolyl‑5‑yl)‑[1,2,5]oxadiazole[3,4‑ b ]pyridine-5,7-diamine. The present invention also discloses a heat-resistant fluorescent active energetic material obtained based on the above method, the molecular formula of which is C6H5N9O and the density is 1.801 g∙cm ‑3 The thermal decomposition temperature is as high as 311℃, the impact sensitivity is >40 J, and the theoretical detonation velocity is 8012 m∙s ‑1 , explosion pressure 29 GPa, can be used as fluorescent explosion marker or high energy filler or additive to make energetic materials easy to detect. The invention has the advantages of simple synthesis, high yield, good comprehensive performance, etc.

Description

Technical Field

[0001] The invention relates to a heat-resistant fluorescent active energetic compound and a preparation method thereof, belonging to the technical field of organic energetic compounds. Background Art

[0002] Energetic materials are usually nitro-substituted compounds, but nitro compounds are common fluorescence quenchers and have no fluorescent properties. So TNT, RDX, HMX, etc. are considered excellent primary explosives because of their high energy, but their detection is very difficult due to the lack of any unique visual properties. In contrast, fluorescent active compounds with energy performance comparable to traditional benchmark energetic materials are better because they are easy to detect.

[0003] However, the synthesis of fluorescent active energetic materials is considered to be a challenging task, and there are very few fluorescent energetic compounds reported in the literature. In 2019, the Shreeve group in the United States reported a fluorescent active compound of 4-amino-1,2,3-triazine-3-nitrogen oxide with pyrazole, imidazole and triazole; in 2023, S. Dharavath et al. of the Indian Institute of Technology, Kanpur, synthesized fluorescent active 4-amino-2H-pyrazolo[3,4-d]pyrimidine-5-oxide. Summary of the invention

[0004] The purpose of the present invention is to provide a heat-resistant fluorescent active energetic compound and a preparation method thereof.

[0005] Technical solution to achieve the purpose of the present invention:

[0006] In the first aspect, the present invention provides a heat-resistant fluorescent active energetic compound named 6-(1H-tetrazolyl-5-yl)-[1,2,5]oxadiazole[3,4-b]pyridine-5,7-diamine, whose chemical formula is C6H5N9O and structural formula is:

[0007]

[0008] In a second aspect, the present invention provides a method for preparing the heat-resistant fluorescent active energetic compound according to the first aspect, comprising:

[0009] (1) adding 2-(amino(4-amino-1,2,5-oxadiazol-3-yl)methylene)malononitrile, sodium azide and ammonium chloride into a solvent DMF, heating to a certain temperature and maintaining the temperature for reaction;

[0010]

[0011] (2) placing the reaction solution obtained in step (1) in ice water under vigorous stirring to quench, acidifying with hydrochloric acid, and then filtering, washing, and drying to obtain the target product 6-(1H-tetrazol-5-yl)-[1,2,5]oxadiazole[3,4-b]pyridine-5,7-diamine.

[0012] Preferably, in step (1), the ratio of 2-(amino(4-amino-1,2,5-oxadiazol-3-yl)methylene)malononitrile to solvent DMF is 1 mmol:2-6 mL; the molar ratio of 2-(amino(4-amino-1,2,5-oxadiazol-3-yl)methylene)malononitrile, sodium azide and ammonium chloride is 1:2-5:2-5.

[0013] Preferably, in step (1), the reaction temperature is 120-150° C. and the insulation time is 8-15 h.

[0014] Preferably, in step (2), the concentration of hydrochloric acid is 5 M, and the solution is acidified to a pH of 1 to 2.

[0015] Preferably, in step (2), washing is performed with ice water.

[0016] In a third aspect, the present invention provides a use of the heat-resistant fluorescent active energetic compound described in the first aspect as a fluorescent explosion marker.

[0017] In a fourth aspect, the present invention provides the use of the heat-resistant fluorescent active energetic compound described in the first aspect as a high-energy filler or additive in an energetic material that is easily detectable.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] (1) The 6-(1H-tetrazolyl-5-yl)-[1,2,5]oxadiazole[3,4-b]pyridine-5,7-diamine of the present invention has fluorescent activity and is easier to detect than traditional energetic materials. It can be used as a fluorescent explosion marker, and can also be used as a main charge or high-energy additive to develop easily detectable explosives.

[0020] (2) The decomposition temperature of the 6-(1H-tetrazolyl-5-yl)-[1,2,5]oxadiazole[3,4-b]pyridine-5,7-diamine of the present invention is as high as 311°C, and the impact sensitivity is >40J. It is a heat-resistant and insensitive energetic compound and has high safety when used.

[0021] (3) The density of 6-(1H-tetrazolyl-5-yl)-[1,2,5]oxadiazole[3,4-b]pyridine-5,7-diamine of the present invention is 1.801 g·cm -3 , with good detonation performance, EXPLO5 calculated detonation velocity 8012m·s -1The theoretical detonation velocity of the heat-resistant fluorescent active energetic compound of the present invention is 500 m·s higher than that of TNT. -1 The explosion pressure is more than 5GPa higher than that of TNT.

[0022] (4) The heat-resistant fluorescent active energetic compound of the present invention is simple to synthesize, has a high yield, and is easy to scale up by engineering; and has the characteristics of fluorescent activity, good heat resistance, low sensitivity, and high energy performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The drawings in the specification, which constitute a part of this application, are used to provide further understanding of this application. The illustrative embodiments of this application and their descriptions are used to explain this application and do not constitute improper limitations on this application.

[0024] Figure 1 The hydrogen nuclear magnetic spectrum of 6-(1H-tetrazol-5-yl)-[1,2,5]oxadiazole[3,4-b]pyridine-5,7-diamine of the present invention (the solvent is deuterated dimethyl sulfoxide).

[0025] Figure 2 The carbon NMR spectrum of 6-(1H-tetrazol-5-yl)-[1,2,5]oxadiazole[3,4-b]pyridine-5,7-diamine of the present invention (the solvent is deuterated dimethyl sulfoxide).

[0026] Figure 3 The infrared spectrum of 6-(1H-tetrazol-5-yl)-[1,2,5]oxadiazole[3,4-b]pyridine-5,7-diamine of the present invention is shown in FIG.

[0027] Figure 4 This is the DSC chart of 6-(1H-tetrazol-5-yl)-[1,2,5]oxadiazolo[3,4-b]pyridine-5,7-diamine of the present invention.

[0028] Figure 5 The ultraviolet-visible absorption spectrum and fluorescence spectrum of 6-(1H-tetrazolyl-5-yl)-[1,2,5]oxadiazole[3,4-b]pyridine-5,7-diamine of the present invention are shown.

[0029] Figure 6 These are fluorescence photographs of DMSO solutions of Comparative Example 1, Comparative Example 2 and Example 16-(1H-tetrazol-5-yl)-[1,2,5]oxadiazole[3,4-b]pyridine-5,7-diamine. DETAILED DESCRIPTION

[0030] It should be noted that the terms such as "upper", "lower", "left", "right", "middle", etc. cited in this specification are only for the convenience of description and are not used to limit the scope of implementation. Changes or adjustments to their relative relationships should be regarded as the scope of implementation of this application without substantially changing the technical content.

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs; the term "and / or" used herein includes any and all combinations of one or more of the associated listed items.

[0032] If the specific conditions are not specified in the examples, the conventional conditions or the conditions recommended by the manufacturer are followed. The raw material 2-(amino(4-amino-1,2,5-oxadiazol-3-yl)methylene)malononitrile is prepared according to the method described in Chemistry of Heterocyclic Compounds, 2020, 56, 1103-1107. The reagents or instruments used without indicating the manufacturer are all conventional products that can be purchased commercially.

[0033] As used herein, the term "about" is used to provide flexibility and imprecision associated with a given term, measurement or value. The degree of flexibility for a particular variable can be easily determined by one skilled in the art.

[0034] As used herein, the term "at least one of" is intended to be synonymous with "one or more of." For example, "at least one of A, B, and C" expressly includes only A, only B, only C, and combinations of each thereof.

[0035] Concentration, amount and other numerical data can be presented in range format herein.It should be understood that such range format is only used for convenience and simplicity, and should be flexibly interpreted as not only including the numerical value clearly described as range limit, but also including all single numerical values ​​or sub-ranges contained in the range, just as each numerical value and sub-range are clearly described.For example, the numerical range of about 1 to about 4.5 should be interpreted as not only including the limit value of 1 to about 4.5 clearly described, but also including single numerals (such as 2,3,4) and sub-ranges (such as 1 to 3,2 to 4, etc.).The same principle is applicable to the scope of only narrating a numerical value, such as "less than about 4.5", which should be interpreted as including all the above-mentioned values ​​and ranges.In addition, no matter how the breadth of the described range or feature is, this explanation should be applicable.

[0036] The heat-resistant fluorescent active energetic compound provided by the present invention is a light yellow powdery solid. Crystal density 1.801 gcm -3It is not sensitive to water, light, and steam. It can be stored in a constant temperature and humidity chamber at 30°C and 90% for three months without deterioration. Its thermal decomposition temperature is higher than 300°C. It does not react with plastics and glass. Its surface color and shape do not change when exposed to direct sunlight for a long time. When exposed to ultraviolet light (365nm) in a dimethyl sulfoxide solution at 25°C, it shows significant fluorescence characteristics and is bright green.

[0037] The method for preparing a heat-resistant fluorescent active energetic compound of the present invention has the following reaction equation:

[0038]

[0039] The specific steps are as follows:

[0040] Step 1: Add the raw materials 2-(amino(4-amino-1,2,5-oxadiazol-3-yl)methylene)malononitrile, sodium azide and ammonium chloride into a solvent DMF at room temperature, heat to 120-150° C., keep the temperature for reaction for 8-15 hours and then cool to room temperature;

[0041] Step 2: Pour the reaction solution into ice water under vigorous stirring to quench, acidify to pH 1-2 with 5M hydrochloric acid, then filter, wash with ice water, and dry to obtain 6-(1H-tetrazol-5-yl)-[1,2,5]oxadiazole[3,4-b]pyridine-5,7-diamine.

[0042] Embodiment 1:

[0043] At room temperature, 2-(amino(4-amino-1,2,5-oxadiazole-3-yl)methylene)malononitrile (881 mg, 5 mmol), ammonium chloride (802 mg, 15 mmol) and sodium azide (975 mg, 15 mol) were added to 20 mL of DMF. The reaction mixture was slowly heated to 120°C and stirred for 10 h. After cooling to room temperature, the reaction solution was poured into ice water with vigorous stirring to quench, acidified to pH 1-2 with 5M hydrochloric acid, then filtered, washed with ice water, and dried to obtain 913 mg of 6-(1H-tetrazol-5-yl)-[1,2,5]oxadiazole[3,4-b]pyridine-5,7-diamine with a yield of 83.3%.

[0044] The 6-(1H-tetrazolyl-5-yl)-[1,2,5]oxadiazole[3,4-b]pyridine-5,7-diamine obtained in Example 1 was characterized, and the analysis results are as follows:

[0045] like Figure 1 The H NMR spectrum shown, 1 H NMR (DMSO-d6): δ 9.28 ppm.

[0046] like Figure 2The NMR carbon spectrum shown, 13 C NMR (DMSO-d6): δ159.00, 156.87, 153.42, 142.24, 139.26, 88.98ppm.

[0047] like Figure 3 Infrared spectrum shown, IR(ATR): 3356,3116,1669,1636,1613,1569,1541,1478,1405,1223,1173,1114,1087,1050,1034 ,894,863,844,820,806,781,766,730,695,665,620,605,597,584,572,561,547,537cm -1 .

[0048] Elemental analysis: C6H5ON9 (219.168): calculated value: C 32.88, H 2.30, N 57.52%; measured value: C32.92, H 2.25, N 57.45%. The molecule does not contain heavy metals and chlorine elements, and will not cause environmental pollution after use.

[0049] The 6-(1H-tetrazolyl-5-yl)-[1,2,5]oxadiazole[3,4-b]pyridine-5,7-diamine obtained in Example 1 was tested and found to have an impact sensitivity of >40 J and a friction sensitivity of >360 N. The mechanical sensitivity is lower than that of TNT and FOX-12, and the product is safer than TNT and FOX-12.

[0050] The 6-(1H-tetrazolyl-5-yl)-[1,2,5]oxadiazole[3,4-b]pyridine-5,7-diamine obtained in Example 1 was tested by DSC. Figure 4 As shown, the initial decomposition temperature is 311°C and the decomposition peak temperature is 357°C.

[0051] The density of 6-(1H-tetrazolyl-5-yl)-[1,2,5]oxadiazole[3,4-b]pyridine-5,7-diamine obtained in Example 1 was tested to be 1.801 g·cm -3 , with excellent detonation performance, EXPLO5 calculated detonation pressure is 29GPa, detonation velocity is 8012m·s -1 .

[0052] The 6-(1H-tetrazolyl-5-yl)-[1,2,5]oxadiazole[3,4-b]pyridine-5,7-diamine obtained in Example 1 was dissolved in DMSO to prepare a solution, and the UV-visible absorption spectrum and fluorescence spectrum were tested. The results were as follows: Figure 5As shown, its ultraviolet absorption is strongest at 370nm; when excited with light of wavelength 300nm, the emission curve shows a peak value (PL maximum) at 530nm.

[0053] The 6-(1H-tetrazolyl-5-yl)-[1,2,5]oxadiazole[3,4-b]pyridine-5,7-diamine obtained in Example 1 was dissolved in DMSO to prepare a solution. The fluorescence activity was as follows: Figure 6 As shown, it appears bright green under 365nm ultraviolet light.

[0054] Embodiment 2:

[0055] At room temperature, 2-(amino(4-amino-1,2,5-oxadiazole-3-yl)methylene)malononitrile (528 mg, 3 mmol), ammonium chloride (802 mg, 15 mmol) and sodium azide (975 mg, 15 mol) were added to 18 mL of DMF. The reaction mixture was slowly heated to 150°C and stirred for 8 h. After cooling to room temperature, the reaction solution was poured into ice water with vigorous stirring to quench, acidified to pH 1-2 with 5M hydrochloric acid, then filtered, washed with ice water, and dried to obtain 578 mg of 6-(1H-tetrazol-5-yl)-[1,2,5]oxadiazole[3,4-b]pyridine-5,7-diamine with a yield of 88.0%.

[0056] Comparative Example 1:

[0057] At room temperature, 6-cyano-[1,2,5]oxadiazole[3,4-b]pyridine-5,7-diamine (881 mg, 5 mmol), ammonium chloride (802 mg, 15 mmol) and sodium azide (975 mg, 15 mol) were added to 20 mL of DMF. The reaction mixture was slowly heated to 120°C and stirred for 10 h. After cooling to room temperature, the reaction solution was poured into ice water with vigorous stirring to quench, acidified to pH 1-2 with 5M hydrochloric acid, and then filtered, washed with ice water, and dried to obtain the unreacted raw material 6-cyano-[1,2,5]oxadiazole[3,4-b]pyridine-5,7-diamine, which is obviously less energetic than the target compound 6-(1H-tetrazol-5-yl)-[1,2,5]oxadiazole[3,4-b]pyridine-5,7-diamine. 6-Cyano-[1,2,5]oxadiazole[3,4-b]pyridine-5,7-diamine was dissolved in DMSO to prepare a solution, and no fluorescence was detected under ultraviolet light at 365 nm.

[0058]

[0059] Comparative Example 2:

[0060] At room temperature, 2-(amino(4-amino-1,2,5-oxadiazole-3-yl)methylene)malononitrile (881 mg, 5 mmol), ammonium chloride (802 mg, 15 mmol) and sodium azide (975 mg, 15 mol) were added to 20 mL of DMF. The reaction mixture was slowly heated to 120 °C and stirred for 3 h. After cooling to room temperature, the reaction solution was poured into ice water with vigorous stirring to quench, acidified to pH 1-2 with 5M hydrochloric acid, and then filtered, washed with ice water, and dried to obtain the product. After separation and characterization, it only contained a small amount of 6-(1H-tetrazolyl-5-yl)-[1,2,5]oxadiazole[3,4-b]pyridine-5,7-diamine, mainly the intermediate 3-amino-3-(4-amino-1,2,5-oxadiazole-3-yl)-2-(1H-tetrazolyl-5-yl)acrylonitrile, whose energy was obviously inferior to the target compound. 3-Amino-3-(4-amino-1,2,5-oxadiazol-3-yl)-2-(1H-tetrazolyl-5-yl)acrylonitrile was dissolved in DMSO to prepare a solution, and no fluorescence was detected under ultraviolet light of 365 nm.

[0061]

[0062] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A heat-resistant fluorescent active energetic compound, characterized in that: It is named 6-(1H-tetrazolyl-5-yl)-[1,2,5]oxadiazole[3,4-b]pyridine-5,7-diamine, its chemical formula is C6H5N9O, and its structural formula is:

2. A method for preparing a heat-resistant fluorescent active energetic compound, characterized in that: include: (1) adding 2-(amino(4-amino-1,2,5-oxadiazol-3-yl)methylene)malononitrile, sodium azide and ammonium chloride into a solvent DMF, heating to a certain temperature and keeping the temperature for reaction for 8 to 15 hours; (2) placing the reaction solution obtained in step (1) in ice water under vigorous stirring to quench, acidifying with hydrochloric acid, and then filtering, washing, and drying to obtain the target product 6-(1H-tetrazol-5-yl)-[1,2,5]oxadiazole[3,4-b]pyridine-5,7-diamine.

3. The method according to claim 2, characterized in that In step (1), the ratio of 2-(amino(4-amino-1,2,5-oxadiazol-3-yl)methylene)malononitrile to solvent DMF is 1 mmol:2-6 mL; the molar ratio of 2-(amino(4-amino-1,2,5-oxadiazol-3-yl)methylene)malononitrile, sodium azide and ammonium chloride is 1:2-5:2-5.

4. The method according to claim 2, characterized in that In step (1), the reaction temperature is 120-150°C.

5. The method according to claim 2, characterized in that In step (2), the concentration of hydrochloric acid is 5M, and the solution is acidified to a pH of 1 to 2.

6. The method according to claim 2, characterized in that In step (2), washing with ice water.

7. Use of the heat-resistant fluorescent active energetic compound as claimed in claim 1 as a fluorescent explosion marker.

8. Use of the heat-resistant fluorescent active energetic compound as claimed in claim 1 as a high-energy filler or additive in an energetic material that is easily detectable.

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