A method for synthesizing a fluorinated dinitropyrazole inner salt

Abstract

This invention discloses a synthetic method for preparing fluoro-dinitropyrazole inner salts from open-chain trinitromethyl functionalized guanidinehydrazone derivatives. The method uses 4,4,4-trinitrobutyraldehyde (I) and aminoguanidine hydrochloride as starting materials, and obtains the intermediate via a nucleophilic addition reaction. N -(4,4,4-trinitrobutylimino)guanidine hydrochloride (II), then intermediate II undergoes intramolecular cyclization under alkaline conditions to yield 2-amidinyl-3-gesidic dinitropyrazole inner salt (III). Inner salt III reacts with a nitric acid-sulfur mixture to generate intermediate 2-( N The inner salt (Ⅳ) of 2-nitro)amidinyl-3-genomicdinitropyrazole was prepared by a substitution reaction between inner salt Ⅳ and xenon difluoride. N (V)-Nitro)amidinyl-3-fluorodinitromethylpyrazole inner salt. This invention utilizes intramolecular cyclization and inner salt-to-inner salt conversion strategies to prepare a fluorodinitropyrazole inner salt that possesses both high thermal stability and high energy with low sensitivity. This substance shows promising application prospects in the field of high explosives.

Description

Technical Field

[0001] This invention belongs to the field of energetic materials and relates to a method for synthesizing a fluorinated geminitropyrazole inner salt. Background Technology

[0002] Energetic materials belong to a special branch of materials science. They can undergo violent redox reactions and release a large amount of energy under certain external stimuli. However, there is an inherent contradiction between energy and stability in energetic compounds, and it is difficult to achieve a perfect balance between high energy and low sensitivity in currently known energetic materials. In recent years, the preparation of energetic ionic salts has become an effective method to balance energy release and chemical stability, but it is still limited by inherent defects such as strong hygroscopicity and relatively low density. Against this background, energetic internal salt materials have become an emerging research hotspot due to their unique advantage of improving thermal stability through electrostatic interactions. However, due to the current limited design and synthesis strategies, the types of energetic internal salts are still scarce, and they generally suffer from insufficient thermal stability and high mechanical sensitivity, as in reference 1 (Du, Y.; Zhang, J.; Peng, P.; Su, H.; Li, S; Pang, S. Synthesis and Characterization of ThreePyrazolate Inner Diazonium Salts: Green, Powerful and Stable PrimaryExplosives). New . J . Chem 2017, 41 (9244−9249.) and Reference 2 (Liu, T.; Liao, S.; Song, S.; Wang, K.; Jin, Y.; Zhang, Q. Combination of Gem -DinitromethylFunctionality and a 5-Amino-1,3,4-Oxadiazole Framework for ZwitterionicEnergetic Materials. Chem . Commun 2020, 56 (2), 209−212.) reported two energetic inner salt compounds, a and b. In view of this, this invention utilizes an intramolecular cyclization and inner salt-to-inner salt conversion strategy to prepare 2-amidinyl-3-geminidinitropyrazole inner salts (III) and 2-( N-nitro)amidinyl-3-fluorodinitromethylpyrazole inner salt (V), compared with a and b above, the thermal stability of III and V ( T d With a temperature increase of >40°C, mechanical sensitivity (friction sensitivity IS and impact sensitivity FS) is significantly improved. This invention provides a new approach for the preparation of novel energetic internal salts with high thermal stability and high safety, accelerating the application of energetic internal salts in weapon systems. To date, research on the preparation and control of the properties of energetic internal salts through intramolecular cyclization and the conversion of internal salts to internal salts has not been publicly reported. Summary of the Invention

[0003] This invention overcomes the shortcomings of the prior art and provides a method for synthesizing fluoro-glycine dinitropyrazole inner salts.

[0004] The technical solution for achieving the objective of this invention is as follows:

[0005] This invention provides a fluoro-glycine dinitropyrazole inner salt, with the following structural formula:

[0006] .

[0007] The X-ray single-crystal diffraction data of the crystal indicate that the substance belongs to the monoclinic crystal system. P twenty one / n Space group; cell parameters are a = 6.1807(3) Å, b = 10.8702(5) Å, c = 15.2531(10) Å, α = 90°, β = 100.483(5)°, γ = 90°; crystal density at 100 K is 1.840 g·cm³. -3 .

[0008] Another object of the present invention is to provide a method for synthesizing fluoro-glycine dinitropyrazole inner salts, the specific steps of which are as follows:

[0009] (1) 4,4,4-Trinitrobutyraldehyde (Ⅰ) reacts with aminoguanidine hydrochloride under hydrochloric acid catalysis to generate N -(4,4,4-trinitrobutylimino)guanidine hydrochloride (II):

[0010]

[0011] (2) N -(4,4,4-trinitrobutylimino)guanidine hydrochloride (II) undergoes a cyclization reaction under alkaline conditions to form 2-amidinyl-3-gesidic dinitropyrazole inner salt (III):

[0012]

[0013] (3) 2-Amino-3-genomicdinitropyrazole inner salt (III) undergoes a nitration reaction in a nitrate-sulfuric acid mixed system to generate 2-( N -nitro)amidin-3-genomicdinitropyrazole inner salt (Ⅳ):

[0014]

[0015] (4) 2-( N -nitro)amidinyl-3-genomicidinitropyrazole inner salt (Ⅳ) reacts with xenon difluoride to form 2-( N (-nitro)amidinyl-3-fluorodinitromethylpyrazole inner salt (V):

[0016]

[0017] Preferably, in step (1), the molar ratio of 4,4,4-trinitrobutyraldehyde (Ⅰ) to aminoguanidine hydrochloride is 1:(1~1.2), the reaction temperature is 0~10°C, and the catalyst used is hydrochloric acid.

[0018] Preferably, in step (1), the solvent used in the reaction system is anhydrous ethanol, and the reaction time is 8~16h.

[0019] Preferably, the specific steps of step (1) are as follows: at 0-10°C, 4,4,4-trinitrobutyraldehyde (I) and aminoguanidine hydrochloride are dissolved in ethanol, and a catalytic amount of hydrochloric acid is added. The resulting mixture is then kept at this temperature for 8-16 hours, filtered, and the filtrate is concentrated using a rotary evaporator to obtain a crude product. Subsequently, the crude product is washed with ethyl acetate and dried to obtain... N -(4,4,4-trinitrobutylimino)guanidine hydrochloride intermediate (II).

[0020] Preferably, in step (2), the... N -(4,4,4-trinitrobutylimino)guanidine hydrochloride (II) was pretreated, specifically by: N -(4,4,4-trinitrobutylimino)guanidine hydrochloride was dissolved in ethanol by stirring, and the pH was adjusted to neutral by adding an alkali (such as triethylamine, sodium methoxide, or sodium ethoxide).

[0021] Preferably, in step (2), the solvent used in the reaction system is anhydrous ethanol, and the reaction time is 2 to 8 hours.

[0022] Preferably, the specific steps of step (2) are as follows: ... N-(4,4,4-trinitrobutylimino)guanidine hydrochloride intermediate (II) was dissolved in ethanol, and an alkali (such as triethylamine, sodium methoxide, sodium ethoxide, etc.) was added until the pH was neutral. Then, the mixture was heated under reflux with stirring for 2-8 hours, cooled, and filtered. The resulting filter cake was washed with ethanol and dried under vacuum to obtain 2-amidinyl-3-gesidiopyrazole inner salt (III).

[0023] Preferably, in step (3), the nitration reaction temperature is -15 to 5°C, the volume ratio of concentrated nitric acid to concentrated sulfuric acid is 1:(1.5 to 2.0), and the reaction time is 2 to 6 hours.

[0024] Preferably, step (3) involves adding 2-amidinyl-3-ges-dinitropyrazole inner salt (III) to 98% H2SO4 under stirring at -15 to 5°C, followed by slow dropwise addition of concentrated HNO3. After the addition is complete, the reaction is maintained at this temperature for 2 to 6 hours. After the reaction is complete, the system is quenched in ice water, extracted with ethyl acetate, washed with brine, and the solvent is evaporated to obtain 2-( N- Nitro)amino-3-genomicidinitropyrazole inner salt (Ⅳ).

[0025] Preferably, in step (4), the solvent used in the reaction system is anhydrous acetonitrile, the reaction temperature is 20-40℃, and the reaction time is 12-36h.

[0026] Preferably, in step (4), 2-( N The molar ratio of (Ⅳ)-nitro)amidinyl-3-ges-dinitropyrazole inner salt to xenon difluoride is 1:(1~2.5).

[0027] Preferably, the specific steps of step (4) are as follows: 2-( N -nitro)amidinyl-3-genomiciol Nitropyrazole inner salt (Ⅳ) was dissolved in anhydrous acetonitrile, and xenon difluoride was added in portions with stirring. The reaction was carried out at 20–40 °C for 12–36 h. The solvent was removed in air, and the remaining solid was recrystallized from ethyl acetate to give 2-( N (V) Nitro)amidinyl-3-fluorodinitromethylpyrazole inner salt.

[0028] The present invention has the following significant advantages compared to existing technologies:

[0029] (1) This invention discloses a method for preparing gemidopyrazole inner salts based on intramolecular cyclization, and achieves the conversion of inner salts to inner salts through functional group modification strategy, effectively controlling the physicochemical properties of energetic inner salts.

[0030] (2) The 2-amidinyl-3-genomicdinitropyrazole inner salt prepared by this invention exhibits superior safety performance compared to most reported energetic inner salts. Its thermal decomposition temperature is 215℃, its friction sensitivity is greater than 360N, and its impact sensitivity is greater than 40J, demonstrating promising application as an insensitive energetic material. Furthermore, the 2-( N The thermal decomposition temperature of the inner salt of (-nitro)amidinyl-3-fluorodinitromethylpyrazole is 181℃, and the detonation velocity is greater than 8000 m / s. -1 With an explosion pressure greater than 29 GPa, it has significant technical advantages in the field of high explosives. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings provide a corresponding description of the present invention:

[0032] Figure 1 for N Crystal ellipsoid diagram of (II)-(4,4,4-trinitrobutylimino)guanidine hydrochloride.

[0033] Figure 2 The crystal ellipsoid diagram of the inner salt (Ⅲ) of 2-amidinyl-3-genomicdinitropyrazole.

[0034] Figure 3 2-( N Crystal ellipsoid diagram of (Ⅳ) nitro)amidinyl-3-genomicdinitropyrazole inner salt.

[0035] Figure 4 2-( N Crystal ellipsoid diagram of (V) nitro)amidinyl-3-fluorodinitromethylpyrazole inner salt.

[0036] Figure 5 for N TG-DSC plot of (II)-(4,4,4-trinitrobutylimino)guanidine hydrochloride.

[0037] Figure 6 TG-DSC plot of 2-amidinyl-3-genomicdinitropyrazole inner salt (III).

[0038] Figure 7 2-( N TG-DSC plot of (Ⅳ) 3-nitro)amidinyl-3-genomicdinitropyrazole inner salt.

[0039] Figure 8 2-( N TG-DSC plot of (V)-nitro)amidinyl-3-fluorodinitromethylpyrazole inner salt.

[0040] Figure 9 2-( N1H NMR spectrum of (V)-nitro)amidinyl-3-fluorodinitromethylpyrazole inner salt.

[0041] Figure 10 2-( N Carbon NMR spectrum of (V) nitro)amidinyl-3-fluorodinitromethylpyrazole inner salt.

[0042] Figure 11 2-( N NMR fluorine spectrum of (V)-nitro)amidinyl-3-fluorodinitromethylpyrazole inner salt. Detailed Implementation

[0043] The present invention will be further described below with reference to the embodiments.

[0044] Example 1

[0045] 2.30 g (11.11 mmol) of 4,4,4-trinitrobutyraldehyde and 1.23 g (11.13 mmol) of aminoguanidine hydrochloride were dissolved in 40 mL of ethanol solution at 5 °C. A catalytic amount of hydrochloric acid was then added, and the mixture was stirred for 12 h. The solution was filtered, and the filtrate was concentrated using a rotary evaporator to obtain the crude product. The crude product was then washed with ethyl acetate and dried to obtain a pale yellow solution. N -(4,4,4-trinitrobutylimino)guanidine hydrochloride solid (II) 3.16 g, yield 95%. Further, the... N -(4,4,4-trinitrobutylimino)guanidine hydrochloride crystals were analyzed using a Bruker Apex-II CCD single-crystal diffractometer, and their single-crystal diffraction patterns are shown below. Figure 1 As shown, this substance belongs to the monoclinic crystal system. P twenty one / c Space group; cell parameters are a = 14.9368(11) Å, b = 11.0777(8) Å, c = 7.7539(6) Å, α = 90°, β = 104.320(4)°, γ = 90°; crystal density at 189.99 K is 1.601 g·cm³. -3 Thermal analysis was performed using a NETZSCH STA 449F5 differential scanning calorimetry-thermogravimetric analysis (TG-DSC) system. The measured TG-DSC curves show that ( Figure 5 The thermal decomposition temperature of this substance is 144℃ (heating rate: 5℃·min). -1 The peak exothermic temperature is 151℃.

[0046] Example 2

[0047] Weigh 3.00g (10.00mmol) N-(4,4,4-trinitrobutylimino)guanidine hydrochloride (prepared in Example 1) was placed in a 100 mL three-necked flask, and 50 mL of ethanol was added and stirred. After the solid was completely dissolved, triethylamine was added until the pH of the solution was neutral. The solution was heated and refluxed with stirring for 6 h. After cooling, the mixture was filtered, and the resulting filter cake was washed with ethanol and dried under vacuum to obtain 1.39 g of 2-amidinyl-3-genomicdinitropyrazole inner salt (III), with a yield of 64%. Further, the 2-amidinyl-3-genomicdinitropyrazole inner salt crystals were analyzed using a Bruker D8 VENTURE single-crystal diffractometer. The single-crystal diffraction pattern is shown below. Figure 2 As shown, this substance belongs to the monoclinic crystal system. P twenty one / n Space group; cell parameters are a = 8.3579(4) Å, b = 12.6021(5) Å, c = 8.3886(4) Å, α = 90°, β = 107.724(2)°, γ = 90°; crystal density at 170 K is 1.706 g·cm³. -3 Thermal analysis was performed using a NETZSCH STA 449F5 differential scanning calorimetry-thermogravimetric analysis (TG-DSC) system. The obtained TG-DSC curves show that ( Figure 6 The thermal decomposition temperature of this substance is 215℃ (heating rate: 5℃·min). -1 The exothermic peak temperature is 243℃. Compared to its ionic salt precursor... N -(4,4,4-trinitrobutylimino)guanidine hydrochloride (II), the thermal stability of this inner salt was significantly improved. The mechanical properties of 2-amidinyl-3-gesidylpyrazole inner salt (III) were tested according to the BAM standard test method (drop weight of 5 kg, test sample amount of 20 mg). The experimental results showed that compound III had an impact sensitivity >40 J and a friction sensitivity >360 N, indicating that it has insensitive properties.

[0048] Example 3

[0049] At 0°C, 0.50 g (2.30 mmol) of 2-amidinyl-3-gesmidinedinitropyrazole inner salt (prepared in Example 2) was slowly added to 2.5 mL of 98% sulfuric acid. After complete dissolution, 1.25 mL of fuming nitric acid was added dropwise, and the reaction was maintained at this temperature for 3 h. After the reaction was complete, the reaction solution was quenched in 20 mL of ice water, extracted with ethyl acetate (3 × 10 mL), the organic phase was washed with brine, and the solvent was evaporated to obtain 2-( N 0.27 g of 2-(nitro)amidinyl-3-genomicidinylpyrazole inner salt (Ⅳ) was obtained, with a yield of 45%. Further, the 2-( N The inner salt crystals of (-nitro)amidinyl-3-genomicdinitropyrazole were analyzed using an XtaLAB single-crystal diffractometer, and their single-crystal diffraction patterns are shown below. Figure 3 As shown, this substance belongs to the monoclinic crystal system.P twenty one / c Space group; cell parameters are a = 14.6387(8) Å, b = 10.0334(5) Å, c = 6.6510(4) Å, α = 90°, β = 95.015(5)°, γ = 90°; crystal density at 114 K is 1.783 g·cm³. -3 Thermal analysis was performed using a NETZSCHSTA 449F5 differential scanning calorimetry-thermogravimetric analysis (TG-DSC) system. The obtained TG-DSC curves show that ( Figure 7 The thermal decomposition temperature of this substance is 215℃ (heating rate: 5℃·min). -1 The peak exothermic temperature is 243℃.

[0050] Example 4

[0051] Take 0.26g (1.00mmol) of 2-( N 2-(nitro)amidinyl-3-genomicidinylpyrazole inner salt (prepared in Example 3) was dissolved in 10 mL of anhydrous acetonitrile, and 0.25 g (1.50 mmol) of xenon difluoride was added in portions with stirring. The reaction was carried out at 30 °C for 20 h. The reaction solvent was removed by evaporation in air, and the remaining solid was recrystallized from ethyl acetate to give a pale yellow 2-( N 0.173 g of 2-(nitro)amidinyl-3-fluorodinitromethylpyrazole inner salt solid (V) was obtained, with a yield of 62%. Further, the 2-( N The inner salt of (-nitro)amidinyl-3-fluorodinitromethylpyrazole was analyzed by nuclear magnetic resonance (NMR) analysis using a Bruker BioSpin GmbH (400 MHz) instrument. The data are as follows: 1 H NMR (400 MHz, DMSO-) d 6): δ = 8.85, 5.98, 3.66, 3.43 ppm; 13 C NMR (101 MHz, DMSO- d 6): δ = 156.38, 152.24, 120.34, 57.15, 38.75 ppm; 19 F NMR (376 MHz, DMSO- d 6): δ = -115.60 ppm. The crystal structure of V was analyzed using a ROD single-crystal diffractometer, and its single-crystal diffraction pattern is shown below. Figure 4 As shown, this substance belongs to the monoclinic crystal system. P twenty one / nSpace group; cell parameters are a = 6.1807(3) Å, b = 10.8702(5) Å, c = 15.2531(10) Å, α = 90°, β = 100.483(5)°, γ = 90°; crystal density at 100 K is 1.840 g·cm³. -3 Thermal analysis was performed using a NETZSCHSTA 449F5 differential scanning calorimetry-thermogravimetric analysis (TG-DSC) system. The obtained TG-DSC curves show that ( Figure 8 The thermal decomposition temperature of this substance is 181℃ (heating rate: 5℃·min). -1 The exothermic peak temperature was 191℃, indicating that the substance has good thermal stability. The enthalpy of formation of V was calculated using the Gaussian 09 software package, and the detonation velocity and detonation pressure were predicted using EXPLO5 6.05.02 software. The theoretical calculation results are: Detonation velocity: 8329 m / s -1 Explosion pressure: 29.4 GPa. According to the BAM standard test method (falling weight 5 kg, test sample amount 20 mg), 2-( N The mechanical properties of (V)-nitro)amino-3-fluorodinitromethylpyrazole inner salt were tested. The experimental results showed that compound V had a friction sensitivity of 35 J and a friction sensitivity of 320 N, indicating that it has low sensitivity characteristics.

[0052] The performance of the products obtained in the prior art and embodiments 2 and 4 of this invention includes the following:

[0053] .

Claims

1. A fluoro-glycine dinitropyrazole inner salt, characterized in that, The structural formula is as follows: 。 2. The fluoro-glycine dinitropyrazole inner salt according to claim 1, characterized in that, The X-ray single-crystal diffraction data of the crystal indicate that the substance belongs to the monoclinic crystal system. P twenty one / n Space group; cell parameters are a = 6.1807(3) Å, b = 10.8702(5) Å, c = 15.2531(10) Å, α = 90°, β = 100.483(5)°, γ = 90°; crystal density at 100 K is 1.840 g·cm³. -3 .

3. The method for synthesizing the fluoro-glycine dinitropyrazole inner salt according to claim 1, characterized in that, Includes the following steps: (1) 4,4,4-Trinitrobutyraldehyde (Ⅰ) reacts with aminoguanidine hydrochloride under hydrochloric acid catalysis to generate N -(4,4,4-trinitrobutylimino)guanidine hydrochloride (II): (2) N -(4,4,4-trinitrobutylimino)guanidine hydrochloride (II) undergoes a cyclization reaction under alkaline conditions to form 2-amidinyl-3-gesidic dinitropyrazole inner salt (III): (3) 2-Amino-3-genomicdinitropyrazole inner salt (III) undergoes a nitration reaction in a nitrate-sulfuric acid mixed system to generate 2-( N -nitro)amidin-3-genomicdinitropyrazole inner salt (Ⅳ): ； The nitric acid-sulfur mixture is a mixture of 98% sulfuric acid and concentrated nitric acid; (4) 2-( N -nitro)amidinyl-3-genomicidinitropyrazole inner salt (Ⅳ) reacts with xenon difluoride to form 2-( N (-nitro)amidinyl-3-fluorodinitromethylpyrazole inner salt (V): 。 4. The synthesis method according to claim 3, characterized in that, In step (1), the molar ratio of 4,4,4-trinitrobenal (Ⅰ) to aminoguanidine hydrochloride is 1:(1~1.2), the reaction temperature is 0~10℃, and the catalyst used is hydrochloric acid; The solvent used in the reaction system is anhydrous ethanol, and the reaction time is 8-16 hours.

5. The synthesis method according to claim 3, characterized in that, In step (2), for N -(4,4,4-trinitrobutylimino)guanidine hydrochloride (II) was pretreated, specifically by: N -(4,4,4-trinitrobutylimino)guanidine hydrochloride was dissolved in ethanol by stirring, and the pH was adjusted to neutral by adding alkali; the solvent used in the reaction system was anhydrous ethanol, and the reaction time was 2-8 hours.

6. The synthesis method according to claim 3, characterized in that, In step (3), the nitration reaction temperature is -15 to 5℃, the volume ratio of concentrated nitric acid to concentrated sulfuric acid is 1:(1.5 to 2.0), and the reaction time is 2 to 6 hours.

7. The synthesis method according to claim 3, characterized in that, In step (4), the solvent used in the reaction system is anhydrous acetonitrile, the reaction temperature is 20–40℃, and the reaction time is 12–36 h; 2-( N The molar ratio of (Ⅳ)-nitro)amidinyl-3-ges-dinitropyrazole inner salt to xenon difluoride is 1:(1~2.5).

8. An energetic material, characterized in that, Includes the fluorinated dinitropyrazole inner salt as described in claim 1 or the fluorinated dinitropyrazole inner salt prepared by the method described in any one of claims 3-7.

9. A powerful explosive, characterized in that, Includes the fluorinated dinitropyrazole inner salt as described in claim 1 or the fluorinated dinitropyrazole inner salt prepared by the method described in any one of claims 3-7.

10. A combustion catalyst ligand, characterized in that, Includes the fluorinated dinitropyrazole inner salt as described in claim 1 or the fluorinated dinitropyrazole inner salt prepared by the method described in any one of claims 3-7.

Images