A method for preparing an energetic material precursor compound
By reacting 2-azido-3-benzothiazol-fluoroborate with pyrazole compounds and directly diazotization on the pyrazole ring, the complexity and risk of synthesis of precursor compounds of diazotpyrazole-energic materials in the prior art was solved, and an efficient and safe synthesis method was achieved, and a precursor compound that can be used to prepare high-energy density energy-containing materials was obtained.
Patent Information
- Application Number
- CN202310258945.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-03-17
- Publication Date
- 2025-05-16
- Estimated Expiration
- 2043-03-17
AI Technical Summary
It is difficult to effectively synthesize precursor compounds of diazopyrazole-based energy-containing material with high energy density and detonation properties in the prior art, and the synthesis method is complex and has high risk.
3-nitro-4-diazo-5-chloropylazole was prepared by reacting 2-azido-3-benzothiazole-fluoroborate with pyrazole compounds and directly diazotization on the pyrazole ring.
A simple and efficient synthesis method is realized, the pyrazole ring reaction activity is improved, and the nitro and diazon groups are combined with chloropyrazole to obtain a precursor compound that can be used to prepare high-energy density energy-containing materials, with high purity and high safety.
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Figure CN116478107B_ABST
Abstract
Description
Technical Field
[0001] The invention relates to a method for preparing an energetic material precursor compound, belonging to the energetic field. Background Art
[0002] With the development of the times, the performance requirements for energetic materials put into use are getting higher and higher. Common energetic substituents such as nitro and diazo groups can significantly increase the density and formation enthalpy of energetic compounds due to the high-energy bonds they provide. Therefore, energetic compounds with the above two types of groups have excellent performance. However, due to the difficulty and high risk of their synthesis, such energetic compounds are rare. In order to synthesize such energetic compounds with excellent performance, it is very necessary to design and synthesize energetic compound precursors that can be modified later. Chloropyrazole is a precursor of a class of energetic materials with high energy density and detonation performance. Since it contains C-Cl bonds that can undergo nucleophilic substitution with amino, hydroxyl and other groups, it is of great research significance to modify its energetic groups to prepare energetic material precursor compounds with both nitro and diazo groups. 2-Azido-3-benzothiazole-fluoroborate is a diazotizing agent widely used in diazo substitution of benzene ring compounds. However, due to the low aromaticity of the pyrazole ring, there is no precedent for successfully introducing a diazo group on the pyrazole ring using 2-azido-3-benzothiazole-fluoroborate. In addition, the general method for preparing diazopyrazoles is to first aminize the pyrazole ring and then diazotize it. This method is not only complicated but also highly dangerous. Therefore, exploring simple and efficient synthetic methods is also of great research significance for the preparation of pyrazole diazo compounds. Summary of the invention
[0003] The purpose of the present invention is to provide a simple method for preparing a diazo pyrazole compound; the method is the first to prepare a pyrazole energetic compound precursor 3-nitro-4-diazo-5-chloropyrazole by reacting 2-azido-3-benzothiazole-fluoroborate with a pyrazole compound to obtain a diazo pyrazole compound. The present invention can improve the reaction activity of the pyrazole ring, and at the same time concentrate the nitro group, the diazo group and the Cl substituent that can be further post-modified on the same pyrazole ring, thereby obtaining a precursor compound that can be used to prepare a new type of high energy density energetic material.
[0004] The purpose of the present invention is achieved through the following technical solutions.
[0005] An energetic material precursor compound, the chemical structure of which is as follows:
[0006]
[0007] A method for preparing an energetic material precursor compound comprises the following steps:
[0008] Step 1, dissolving 3-chloro-5-nitropyrazole in methanol, then adding 2-azido-3-benzothiazole-fluoroborate, heating and reflux, controlling the temperature at 55°C to 60°C, and reacting for 10 to 30 minutes to obtain a system; the amount of the substance added is 3-chloro-5-nitropyrazole 584-1168 mg (4 mMol-8 mMol), methanol 14-28 ml, 2-azido-3-benzothiazole-fluoroborate 1.168-2.336 g (4 mMol-8 mMol);
[0009] Step 2: Rapidly cool the reaction system described in step 1 to below 0°C, and the reaction time is 10 to 30 minutes. Then filter out the yellow solid and wash it with cold methanol. Finally, dry the obtained yellow solid with silica gel under vacuum at 60°C to 80°C for 12 to 24 hours. The obtained solid is the target product 3-nitro-4-diazo-5-chloropyrazole.
[0010] Beneficial Effects
[0011] 1. A method for preparing an energetic material precursor compound of the present invention directly performs diazotization on the pyrazole ring in one step by controlling the amount of substrate and reaction conditions.
[0012] 2. The present invention combines nitro and azo groups with chloropyrazole to obtain a class of energetic material precursor compounds 3-nitro-4-diazo-5-chloropyrazole that can be used for post-modification and has great potential for preparing high-energy-density energetic materials. The preparation method is simple and smooth, highly safe, and the product purity is high. BRIEF DESCRIPTION OF THE DRAWINGS
[0013] Figure 1 and Figure 2 is a single crystal structure diagram of 3-nitro-4-diazo-5-chloropyrazole of the present invention;
[0014] Figure 3 The nuclear magnetic resonance of 3-nitro-4-diazo-5-chloropyrazole of the present invention is 1 H spectrum;
[0015] Figure 4 It is the infrared spectrum of 3-nitro-4-diazo-5-chloropyrazole of the present invention. DETAILED DESCRIPTION
[0016] The present invention and its implementation methods are described below, and the actual implementation methods are limited to the specific dosage ranges. In short, if ordinary technicians in the field are inspired by it, without departing from the purpose of the invention, they can design structural methods and embodiments similar to the technical solution without creativity, which should all fall within the protection scope of the present invention.
[0017] Example 1 The target product can be obtained by using the reaction substrate in the dosage range described above;
[0018] The amount of the reaction substrate in Comparative Examples 1 and 2 was outside the above range, and the target product was not obtained.
[0019] Embodiment 1:
[0020] The synthetic route of 3-nitro-4-diazo-5-chloropyrazole is as follows:
[0021]
[0022] The specific synthesis steps are as follows:
[0023] Dissolve (584-1168 mg, 4-8 mmol) 3-chloro-5-nitropyrazole in 14-28 ml methanol, then add (1.168-2.236 g, 4-8 mmol) 2-azido-3-benzothiazole-fluoroborate, heat to 55°C and reflux for 10-30 min to obtain a yellow turbid solution. Then cool the system and keep the temperature below 0°C to continue the reaction for 10-30 min, then filter the solid and wash it with a large amount of cold methanol, and finally dry the obtained solid on silica gel under vacuum conditions for 12-24 h. The final solid is the target product 3-nitro-4-diazo-5-chloropyrazole.
[0024] IR(cm -1 )v~=3391, 3238, 2234, 2170, 1676, 1554, 1518, 1487, 1460, 1395, 1346,
[0025] 1319, 1292, 1175, 1110, 1049, 1040, 1026, 835, 774, 754, 738, 709, 690, 642, 622, 590, 452.
[0026] Comparative Example 1:
[0027] (292 mg, 2 mmol) 3-chloro-5-nitropyrazole was dissolved in 8 ml methanol, followed by the addition of (0.584 g, 2 mmol) 2-azido-3-benzothiazole-fluoroborate, and the temperature was raised to 55°C and refluxed for 10 to 30 min. The system was then cooled to room temperature, and solids were generated. The solids were then filtered and washed with a large amount of cold methanol. Finally, the obtained solids were dried on silica gel under vacuum conditions for 12 to 24 h. Characterization showed that the solids were the raw materials rather than the target compound.
[0028] Comparative Example 2:
[0029] (1752 mg, 12 mmol) 3-chloro-5-nitropyrazole was dissolved in 24 ml methanol, followed by the addition of (3.504 g, 12 mmol) 2-azido-3-benzothiazole-fluoroborate, and the temperature was raised to 55°C and refluxed for 10 to 30 min. The system was then cooled to room temperature, and solids were generated. The solids were then filtered and washed with a large amount of cold methanol. Finally, the obtained solids were dried on silica gel under vacuum conditions for 12 to 24 h. Characterization showed that the solids were the raw materials rather than the target compound.
[0030] The specific description above further illustrates the purpose, technical solutions and beneficial effects of the invention in detail. It should be understood that the above is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.
Claims
1. A method for preparing an energetic material precursor compound, characterized in that: The following steps are involved: Step 1, dissolving 3-chloro-5-nitropyrazole in methanol, then adding 2-azido-3-benzothiazole-fluoroborate, heating and reflux, controlling the temperature at 55°C to 60°C, and reacting for 10 to 30 minutes to obtain a system; the amount of the substance added is 3-chloro-5-nitropyrazole 584-1168 mg, methanol 14-28 ml, 2-azido-3-benzothiazole-fluoroborate 1.168-2.336 g; Step 2: Rapidly cool the reaction system described in step 1 to below 0°C, and the reaction time is 10 to 30 minutes. Then filter out the yellow solid and wash it with cold methanol. Finally, dry the obtained yellow solid with silica gel under vacuum at 60°C to 80°C for 12 to 24 hours. The obtained solid is the target product 3-nitro-4-diazo-5-chloropyrazole. The chemical structural formula of the energetic material precursor compound is as follows: