Synthesis method of tetranitropyrazol tetrazine energetic material

Abstract

The invention discloses a method for synthesizing 1,2,9,10-tetranitropyrazole [1,5-d:5',1'-f] [1,2,3,4] tetrazine, belonging to the field of energetic material synthesis. H ,2' H The energetic material is prepared by using ‑3,3'‑bipyrazole as a raw material through a three-step reaction of nitration, amination and oxidation. The method has the advantages of short reaction route, good stability and high safety, and can effectively solve the problems of long synthesis route, low yield and environmental unfriendliness in the prior art.

Description

Technical Field

[0001] The invention relates to a preparation method of a tetranitropyrazole tetrazine energetic material, in particular to a synthesis method of a 1,2,9,10-tetranitropyrazole [1,5-d:5',1'-f] [1,2,3,4] tetrazine energetic material, belonging to the technical field of organic energetic materials. Background Art

[0002] As a carrier for storing and releasing chemical energy, energetic materials play an irreplaceable role in the military and civilian fields. FPTX (1,2,9,10-tetranitropyrazole [1,5-d:5',1'-f] [1,2,3,4] tetrazine) is a high-energy-density condensed-ring energetic material with six nitrogen atoms directly connected. It has a detonation performance comparable to that of CL-20, and its detonation velocity is as high as 9631 m s -1 , with an explosion pressure of 44 GPa. In addition, FPTX also exhibits a higher heat of formation (FPTX: 2.23 kJ g -1 vs CL-20:0.91kJ g -1 ) and a higher initial thermal decomposition temperature (FPTX: 233℃ vs CL-20: 195℃), and the sensitivity (IS=10J) is more insensitive than CL-20 (IS=4J). More importantly, FPTX exhibits extremely high stability, and its properties have not changed significantly after being stored at room temperature for two years. In summary, thanks to its high energy, high formation enthalpy, high thermal stability, low mechanical sensitivity and easy storage at room temperature, it can be used as a new generation of energetic materials to replace CL-20 in national defense and people's livelihood. At present, only one document (J.Am.Chem.Soc.2017,139,13684-13687) has reported a method for preparing FPTX, and this method requires the preparation of FPTX through five steps of multi-step nitration (N-nitration, nitro transfer, C-nitration), amination and oxidation. Among them, it takes three steps to prepare 4,4',5,5'-tetranitro-2H,2'H-3,3'-bipyrazole (4) from 2H,2'H-3,3'-bipyrazole (1), which seriously limits its potential for expanding production and industrial application. In addition, the three-step reaction involves the separation of nitration products, and there are problems such as harsh reaction conditions, low yield, and poor safety. Therefore, it is urgent to find a green, safe, and efficient nitration method to improve the synthesis efficiency of compound 4, so as to expand the potential for FPTX production and industrial application.

[0003] Summary of the invention

[0004] The object of the present invention is to provide a method for preparing FPTX (1,2,9,10-tetranitropyrazole [1,5-d:5',1'-f] [1,2,3,4] tetrazine) energetic material with short reaction route, high safety, high total yield and good stability.

[0005] The technical solution to achieve the purpose of the present invention is: a method for preparing 1,2,9,10-tetranitropyrazole [1,5-d:5',1'-f] [1,2,3,4] tetrazine energetic materials, specifically comprising the following steps:

[0006] 1) adding compound 1 to a nitration system of KNO3 / H2SO4 at 0°C, heating to 100°C and reacting for at least 72h to prepare compound 4;

[0007]

[0008] 2) a step of subjecting compound 4 to an amination reaction with an animating reagent to prepare compound 5;

[0009]

[0010] 3) a step of subjecting compound 5 to an oxidative coupling reaction with tert-butyl hypochlorite to prepare the target product FPTX;

[0011]

[0012] Preferably, in step 1), in the nitration system of KNO3 / H2SO4 / , sulfuric acid can be any one of concentrated sulfuric acid, 20wt% oleum, and 30wt% oleum, and the mass ratio of compound 1 to potassium nitrate and sulfuric acid is 1:10:30 to 1:10:60.

[0013] Preferably, in step 2), the amination reagent is hydroxylamine oxysulfonic acid or O-toluenesulfonylhydroxylamine.

[0014] Preferably, in step 2), the reaction is carried out in the presence of an alkaline substance, using acetonitrile as the reaction solvent, wherein the alkaline substance can be any one of potassium hydroxide, sodium bicarbonate, and 1,8-diazabicyclopentane-dec-7-ene.

[0015] Preferably, in step 3), acetonitrile is used as the reaction solvent.

[0016] Compared with the prior art, the present invention has the following beneficial effects: the present invention adopts a three-step method for synthesizing FPTX (1,2,9,10-tetranitropyrazole [1,5-d:5',1'-f] [1,2,3,4] tetrazine). Compared with the traditional method, the present invention has a short synthesis route and high reaction efficiency. Among them, the synthesis method of compound 4, which originally required three steps of nitration to obtain, is shortened to one step, which improves the safety of the reaction and improves the safety guarantee for future industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is the hydrogen spectrum of 4,4',5,5'-tetranitro-2H,2'H-3,3'-bipyrazole (4).

[0018] Figure 2 This is the carbon spectrum of 4,4',5,5'-tetranitro-2H,2'H-3,3'-bipyrazole (4).

[0019] Figure 3 This is the actual sample image of 4,4',5,5'-tetranitro-2H,2'H-3,3'-bipyrazole (4).

[0020] Figure 4 This is the crystal structure of 1,2,9,10-tetranitropyrazole[1,5-d:5',1'-f][1,2,3,4]tetrazine energetic material (FPTX).

[0021] Figure 5 This is an actual sample picture of 1,2,9,10-tetranitropyrazole [1,5-d:5',1'-f][1,2,3,4] tetrazine energetic material (FPTX). DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solution and advantages of the present invention clearer, the following is a further detailed description in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described are only used to explain this patent, but not to limit this invention.

[0023] The present invention provides a method for synthesizing FPTX (1,2,9,10-tetranitropyrazole [1,5-d:5',1'-f] [1,2,3,4] tetrazine) energetic material. The core idea is: using compound 1 (4,4',5,5'-tetranitro-2H,2'H-3,3'-bipyrazole) as a starting material, and preparing FPTX (1,2,9,10-tetranitropyrazole [1,5-d:5',1'-f] [1,2,3,4] tetrazine) energetic material by a three-step method of one-step nitration, amination and oxidation.

[0024] The preparation method of 1,2,9,10-tetranitropyrazole [1,5-d:5',1'-f] [1,2,3,4] tetrazine energetic material specifically comprises the following steps:

[0025] 1) slowly adding compound 1 in batches to a KNO3 / H2SO4 nitration system at 0°C. After the addition is completed, the temperature is raised to 100°C and the reaction is continued at this temperature for at least 72 hours. After the reaction is completed, the reaction is quenched with ice water and extracted with an organic solvent that is immiscible with water. The organic phase is concentrated to obtain compound 4. The organic solvent can be any one of anhydrous ether, ethyl acetate, dichloromethane or an ether with 2 to 6 carbon atoms;

[0026] 2) adding two equivalents of an alkaline substance to the acetonitrile solution of compound 4 and stirring for 30 minutes, then adding hydroxylamine oxysulfonic acid or O-toluenesulfonylhydroxylamine freshly prepared in dichloromethane, stirring at room temperature for 3 hours, and concentrating the reaction solution to obtain compound 5. The alkaline substance can be any one of potassium hydroxide, sodium bicarbonate, and 1,8-diazabicyclopentane-dec-7-ene;

[0027] 3) Slowly add tert-butyl hypochlorite to the acetonitrile solution of compound 5 and stir for 30 minutes. After the reaction is completed, FPTX can be obtained by extraction.

[0028] The overall synthetic route is as follows:

[0029]

[0030] Example 1

[0031] 1) At 0°C, potassium nitrate (10.00 g) was slowly added to concentrated sulfuric acid (60.00 g) in batches, and then compound 1 (1.00 g, 7.45 mmol) was slowly added to the nitration system in batches. After the addition was completed, the temperature was raised to 100°C and the reaction was continued at this temperature for 96 hours. After the reaction was completed, the reaction solution was poured into 100 mL of ice water to quench, and extracted with 75 mL of anhydrous ether. The anhydrous ether phase was concentrated to obtain compound 4 (0.79 g, 2.51 mmol), and its hydrogen spectrum, carbon spectrum and actual sample diagram are shown in Figures 1 and 2. Figure 1 , Figure 2 and Figure 3 ;

[0032] 2) At room temperature, 1,8-diazabicycloundec-7-ene (1.22 g, 8.00 mmol) was added dropwise to a solution of compound 4 (1.26 g, 4.00 mmol) in acetonitrile (30 mL) and stirred at this temperature for 30 min, then hydroxylamine sulfonic acid (0.95 g, 8.40 mmol) or freshly prepared O-toluenesulfonylhydroxylamine (1.57 g, 8.40 mmol) in dichloromethane (100 mL) was added to the reaction solution and the reaction was continued for 3 h. After the reaction was completed, the reaction solution was concentrated to obtain compound 5 (0.63 g, 1.83 mmol);

[0033] 3) At 0°C, tert-butyl hypochlorite (0.76 g, 6.97 mmol) was added dropwise to an acetonitrile solution (30 mL) of 5 (2.00 g, 5.81 mmol), and the reaction was continued at this temperature for 30 min. After the reaction was completed, the mixture was concentrated, washed, and dried to obtain compound FPTX (0.83 g, 2.44 mmol). Its crystal structure is as follows Figure 4 As shown in the sample diagram Figure 5 shown.

[0034] Example 2

[0035] 1) At 0°C, potassium nitrate (10.00 g) was slowly added in batches to 30% fuming sulfuric acid (30.00 g), and then compound 1 (1.00 g, 7.45 mmol) was slowly added in batches to the nitration system. After the addition was completed, the temperature was raised to 100°C and the reaction was continued at this temperature for 72 hours. After the reaction was completed, the reaction solution was poured into 100 mL of ice water to quench, and extracted with 75 mL of ethyl acetate, and the ethyl acetate phase was concentrated to obtain compound 4 (0.83 g, 2.64 mmol);

[0036] Step 2) and step 3) are the same as in Example 1.

[0037] Example 3

[0038] 1) At 0°C, potassium nitrate (10.00 g) was slowly added in batches to 20% fuming sulfuric acid (40.00 g), and then compound 1 (1.00 g, 7.45 mmol) was slowly added in batches to the nitration system. After the addition was completed, the temperature was raised to 100°C and the reaction was continued at this temperature for 80 hours. After the reaction was completed, the reaction solution was poured into 100 mL of ice water to quench, and extracted with 75 mL of dichloromethane, and the dichloromethane phase was concentrated to obtain compound 4 (0.77 g, 2.45 mmol);

[0039] Step 2) and step 3) are the same as in Example 1.

[0040] Example 4

[0041] 1) At 0°C, potassium nitrate (50.00 g) was slowly added in batches to 30% fuming sulfuric acid (150.00 g), and then compound 1 (5.00 g, 37.27 mmol) was slowly added in batches to the nitration system. After the addition was completed, the temperature was raised to 100°C and the reaction was continued at this temperature for 72 hours. After the reaction was completed, the reaction solution was poured into 100 mL of ice water to quench, and extracted with 75 mL of dichloromethane, and the dichloromethane phase was concentrated to obtain compound 4 (3.43 g, 10.92 mmol);

[0042] Step 2) and step 3 )Same as Example 1.

[0043] Comparative Example 1

[0044] At 0°C, potassium nitrate (10.00 g) was slowly added in portions to 2 0% fuming sulfuric acid (40.00 g), and then slowly add compound 1 (1.00 g, 7.45 mmol) to the nitration system in batches. After the addition is completed, the temperature is raised to 80°C and the reaction is continued at this temperature for 7 2 h. After the reaction was completed, the reaction solution was poured into 100 mL of ice water to quench, and extracted with 75 mL of dichloromethane. The dichloromethane phase was concentrated, but compound 4 was not obtained;

[0045] Comparative Example 2

[0046] 1) At 0°C, 100% nitric acid (15.00 g) was slowly added in batches to 20% fuming sulfuric acid (40.00 g), and then compound 1 (1.00 g, 7.45 mmol) was slowly added in batches to the nitration system. After the addition was completed, the temperature was raised to 100°C and the reaction was continued at this temperature for 72 hours. After the reaction was completed, the reaction solution was poured into 100 mL of ice water to quench, and extracted with 75 mL of ethyl acetate. The ethyl acetate phase was concentrated, but compound 4 was not obtained.

Claims

1. A method for synthesizing 1,2,9,10-tetranitropyrazole [1,5-d:5',1'-f] [1,2,3,4] tetrazine energetic materials, characterized in that: The following steps are involved: 1) adding compound 1 to a nitration system of KNO3 / H2SO4 at 0°C, heating to 100°C and reacting for at least 72h to prepare compound 4; 2) a step of subjecting compound 4 to an amination reaction with an aminating agent to prepare compound 5; 3) a step of subjecting compound 5 to an oxidative coupling reaction with tert-butyl hypochlorite to prepare a target product; 2. The method according to claim 1, characterized in that In step 1), in the KNO3 / H2SO4 nitration system, the sulfuric acid is any one of concentrated sulfuric acid, 20wt% fuming sulfuric acid, and 30wt% fuming sulfuric acid, and the mass ratio of compound 1 to potassium nitrate and sulfuric acid is 1:10:30 to 1:10:

60.

3. The method according to claim 1, characterized in that In step 2), the amination reagent is any one of hydroxylamine oxysulfonic acid or O-toluenesulfonylhydroxylamine.

4. The method according to claim 1, characterized in that In step 2), the reaction is carried out in the presence of an alkaline substance, wherein the alkaline substance is any one of potassium hydroxide, sodium bicarbonate, and 1,8-diazabicyclopentane-dec-7-ene.

5. The method according to claim 1, characterized in that In step 2), acetonitrile is used as the reaction solvent.

6. The method according to claim 1, characterized in that In step 3), acetonitrile is used as the reaction solvent.

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