A class of energetic compounds of 3-(3,5-dinitrophenyl)-1,2,4-oxadiazole and their synthetic methods

Abstract

This invention discloses a method for synthesizing a class of energetic compounds of 3-(3,5-dinitrophenyl)-1,2,4-oxadiazole. The structural feature of these compounds is a 3-(3,5-dinitrophenyl)-1,2,4-oxadiazole ring as the basic skeleton, with trifluoromethyl, trichloromethyl, amino, methylazido, and methyl hydroxyl groups as substituents. This invention belongs to the field of energetic materials technology. The 5-trifluoromethyl-3-(3,5-dinitrophenyl)-1,2,4-oxadiazole and 5-methylazido-3-(3,5-dinitrophenyl)-1,2,4-oxadiazole described in this invention possess low melting points and low sensitivity, showing promising applications in cast-supported explosives.

Description

Technical Field

[0001] This invention belongs to the field of energetic materials technology, and particularly relates to a method for synthesizing a class of energetic compounds of 3-(3,5-dinitrophenyl)-1,2,4-oxadiazole with low melting point and low sensitivity. Background Technology

[0002] Cast-molten explosives are currently the most widely used type of military mixed explosives, accounting for over 90% of all military mixed explosives and holding a crucial position within this category. Cast-molten explosives are mixed explosives formed by adding high-energy explosives to a relatively insensitive explosive carrier. They are suitable for chambers of various shapes and exhibit excellent overall performance.

[0003] Traditional cast-carrier explosives, such as trinitrotoluene (TNT), suffer from numerous drawbacks, including low energy, unsatisfactory mechanical properties, poor safety performance, and high toxicity. They are gradually being replaced by dinitroanisole (DNAN), but DNAN suffers from low density and low energy levels. Therefore, countries worldwide are continuously exploring and searching for novel liquid-phase carrier explosives with high energy and low sensitivity. Currently, novel cast-carrier explosives have been developed, represented by 3,4-dinitropyrazole (DNP), 1,3,3-trinitroazacyclobutane (TNAZ), 1-methyl-3,4,5-trinitropyrazole (MTNP), and 3,3'-bi-(1,2,4-oxadiazole)-5,5'-dimethyl nitrate (BODN). However, the variety of cast-carrier explosives remains limited, and there is an urgent need to design and develop novel cast-carrier explosives with superior overall performance.

[0004] A class of 3-(3,5-dinitrophenyl)-1,2,4-oxadiazole energetic compounds, which structurally combine a nitrobenzene ring and an oxadiazole heterocycle, are shown in (I).

[0005]

[0006] R=CF3, CCl3, NH2, CH2N3, CH2OH. Summary of the Invention

[0007] The purpose of this invention is to provide a class of energetic compounds of the 3-(3,5-dinitrophenyl)-1,2,4-oxadiazole class, which possess both low sensitivity and low melting point. Their structural characteristics include a 3-(3,5-dinitrophenyl)-1,2,4-oxadiazole ring as the basic skeleton, with methyl azide and substituents such as trifluoromethyl, trichloromethyl, amino, and methyl hydroxyl groups. These compounds have suitable melting points and are simple to synthesize, showing promising applications in cast-supported explosives.

[0008] The purpose of this invention is to provide a method for synthesizing a class of energetic compounds containing 3-(3,5-dinitrophenyl)-1,2,4-oxadiazole.

[0009] The synthesis method of this invention is simple, the reaction conditions are mild, the raw materials are readily available, and the product yield is high.

[0010] The objective of this invention is achieved through the following technical solution:

[0011] The method for synthesizing 5-trifluoromethyl-3-(3,5-dinitrophenyl)-1,2,4-oxadiazole according to the present invention is achieved by the following steps: (1) 3,5-dinitrobenzylaminoxime is added to a certain amount of a mixed solution of trifluoroacetic anhydride and trifluoroacetic acid under mechanical stirring at 0-40°C; (2) The system is heated to 90°C and refluxed for 3-16 hours; (3) The system is cooled to room temperature, an appropriate amount of ice water is added, and a white solid is precipitated; (4) After stirring, the solid is filtered and dried to obtain the 5-trifluoromethyl-3-(3,5-dinitrophenyl)-1,2,4-oxadiazole product.

[0012] The method for synthesizing 5-trichloromethyl-3-(3,5-dinitrophenyl)-1,2,4-oxadiazole according to the present invention is achieved by the following steps: (1) 3,5-dinitrobenzylaminoxime is added to a certain amount of trichloroacetic anhydride at 0-40°C with mechanical stirring; (2) The system is heated to 90°C and refluxed for 0.5-3 hours; (3) The system is cooled to room temperature, an appropriate amount of ice water is added, and a white solid is precipitated; (4) After stirring, the solid is filtered and dried to obtain the 5-trichloromethyl-3-(3,5-dinitrophenyl)-1,2,4-oxadiazole product.

[0013] The method for synthesizing 5-amino-3-(3,5-dinitrophenyl)-1,2,4-oxadiazole according to the present invention is achieved through the following steps: (1) a certain amount of NaOH solid is added to a three-necked flask, and excess ammonia water is added to a constant pressure dropping funnel to prepare ammonia gas; (2) 5-trichloromethyl-3-(3,5-dinitrophenyl)-1,2,4-oxadiazole is dissolved in a certain amount of methanol and placed in an ice bath at 0°C for stirring; (3) excess ammonia gas is introduced by slow bubbling, and the white solid gradually dissolves. The bubbling reaction is continued for 3 to 8 hours; (4) after the reaction is completed, the reaction is raised to room temperature; (5) the mixture is filtered and washed with a small amount of methanol to obtain the 5-amino-3-(3,5-dinitrophenyl)-1,2,4-oxadiazole product.

[0014] The method for synthesizing 5-methylazido-3-(3,5-dinitrophenyl)-1,2,4-oxadiazole according to the present invention is achieved by the following steps: (1) 3,5-dinitrobenzyl oxime is suspended in a certain amount of toluene at 0-40°C with mechanical stirring; (2) 2-3 equivalents of chloroacetyl chloride in toluene solution is added dropwise; (3) The mixture is heated to 110°C and refluxed for 4-6 hours; (4) The mixture is cooled to room temperature and the solvent is evaporated to obtain a white intermediate; (5) The white intermediate is dissolved in a certain amount of acetonitrile, and 1-2 equivalents of NaN3 are added, and the mixture is stirred at 55°C for 8-12 hours; (6) The mixture is cooled to room temperature, the solution is placed on ice water, and stirred for 30 minutes; (7) The mixture is filtered and dried to obtain the 5-methylazido-3-(3,5-dinitrophenyl)-1,2,4-oxadiazole product.

[0015] The method for synthesizing 5-methylhydroxy-3-(3,5-dinitrophenyl)-1,2,4-oxadiazole according to the present invention is achieved through the following steps: (1) under mechanical stirring at 0-40°C, 3,5-dinitrobenzylaminoxime is dissolved in a certain amount of acetonitrile, and 1-2 equivalents of K2CO3 are added; (2) 1-1.5 equivalents of acetoxyacetyl chloride solution in acetonitrile is added dropwise; (3) the temperature is raised to 83°C and refluxed for 3-6 hours; (4) the temperature is cooled to room temperature and the solvent is evaporated; (5) (6) Dilute the solid with a certain amount of water, then extract with a certain amount of ethyl acetate and collect the organic phase; (7) Dry the organic phase with anhydrous MgSO4 and then evaporate to obtain a purplish-black intermediate; (8) Dissolve the purplish-black intermediate in a certain amount of methanol solvent; (9) Add 0.1 to 1 equivalent of K2CO3, heat to 65℃ and reflux for 2 to 4 hours; (10) Evaporate the solvent, wash the solid with a small amount of water, and dry to obtain 5-methylhydroxy-3-(3,5-dinitrophenyl)-1,2,4-oxadiazole product.

[0016] The present invention provides a sample of a class of 3-(3,5-dinitrophenyl)-1,2,4-oxadiazole energetic compounds. The structure of the product was confirmed by elemental analysis, infrared spectroscopy, carbon NMR spectroscopy, proton NMR spectroscopy, and X-ray single crystal diffraction. The thermal decomposition characteristics, mechanical impact sensitivity, and friction sensitivity of the product were tested, and its detonation performance was evaluated. Its application in the field of energetic materials is disclosed.

[0017] Beneficial effects

[0018] 1. The 3-(3,5-dinitrophenyl)-1,2,4-oxadiazole energetic compound described in this invention has a stable structure and good thermal stability and low sensitivity.

[0019] 2. The method for synthesizing a class of 3-(3,5-dinitrophenyl)-1,2,4-oxadiazole energetic compounds described in this invention is simple, the reaction conditions are mild, the raw materials are readily available, and the product yield is high.

[0020] 3. The 5-methylazido-3-(3,5-dinitrophenyl)-1,2,4-oxadiazole and 5-trifluoromethyl-3-(3,5-dinitrophenyl)-1,2,4-oxadiazole described in this invention can be used in the field of high-energy, low-sensitivity cast-carrier explosives. Attached Figure Description

[0021] Figure 1 The molecular structure diagram of 5-trifluoromethyl-3-(3,5-dinitrophenyl)-1,2,4-oxadiazole;

[0022] Figure 2 The carbon NMR spectrum of 5-trifluoromethyl-3-(3,5-dinitrophenyl)-1,2,4-oxadiazole;

[0023] Figure 3 The 1H NMR spectrum of 5-trifluoromethyl-3-(3,5-dinitrophenyl)-1,2,4-oxadiazole;

[0024] Figure 4 The molecular structure diagram of 5-trichloromethyl-3-(3,5-dinitrophenyl)-1,2,4-oxadiazole;

[0025] Figure 5 The carbon NMR spectrum of 5-trichloromethyl-3-(3,5-dinitrophenyl)-1,2,4-oxadiazole;

[0026] Figure 6 The 1H NMR spectrum of 5-trichloromethyl-3-(3,5-dinitrophenyl)-1,2,4-oxadiazole;

[0027] Figure 7 The molecular structure diagram of 5-amino-3-(3,5-dinitrophenyl)-1,2,4-oxadiazole;

[0028] Figure 8 The carbon NMR spectrum of 5-amino-3-(3,5-dinitrophenyl)-1,2,4-oxadiazole;

[0029] Figure 9 The 1H NMR spectrum of 5-amino-3-(3,5-dinitrophenyl)-1,2,4-oxadiazole;

[0030] Figure 10 The molecular structure diagram of 5-methylazido-3-(3,5-dinitrophenyl)-1,2,4-oxadiazole;

[0031] Figure 11 The carbon NMR spectrum of 5-methylazido-3-(3,5-dinitrophenyl)-1,2,4-oxadiazole;

[0032] Figure 12 The 1H NMR spectrum of 5-methylazido-3-(3,5-dinitrophenyl)-1,2,4-oxadiazole;

[0033] Figure 13 The molecular structure diagram of 5-methylhydroxy-3-(3,5-dinitrophenyl)-1,2,4-oxadiazole;

[0034] Figure 14 The carbon NMR spectrum of 5-methylhydroxy-3-(3,5-dinitrophenyl)-1,2,4-oxadiazole;

[0035] Figure 15 The 1H NMR spectrum of 5-methylhydroxy-3-(3,5-dinitrophenyl)-1,2,4-oxadiazole; Detailed Implementation

[0036] The present invention is implemented through the following embodiments, but the conditions and results described in the implementation do not constitute a limitation on the content and rights of the invention.

[0037] Example 1: Synthesis of 5-trifluoromethyl-3-(3,5-dinitrophenyl)-1,2,4-oxadiazole

[0038] The specific synthesis method of 5-trifluoromethyl-3-(3,5-dinitrophenyl)-1,2,4-oxadiazole is as follows: (1) Take 0.50g (2.2mmol) of dinitrobenzyl oxime and add it to a mixed solution of 5mL (35.9mmol) trifluoroacetic anhydride and 5mL (61.7mmol) trifluoroacetic acid under stirring. (2) Heat the system to 90℃ and reflux for 6h. (3) Cool to room temperature, add 20mL of ice water, and a white solid precipitates. (4) Stir for 30min, filter, and dry to obtain 0.54g of white powder with a yield of 88.7%.

[0039] DSC (10℃·min) -1 ): 97℃ (mp); 13 C NMR (101MHz, DMSO-d6, 25℃) δ: 166.55, 166.50, 149.36, 127.67, 122.30, 117.41, 114.70. 1 H NMR (400MHz, DMSO) δ9.12 (1H), 9.09 (2H); IR (KBr, ν / cm -1 ):3093(m),1555(s),1544(s),1346(s),1185(s),1144(s),1080(w),920(m),765(m).

[0040] Example 2 Synthesis of 5-trichloromethyl-3-(3,5-dinitrophenyl)-1,2,4-oxadiazole

[0041] The specific synthesis method of 5-trichloromethyl-3-(3,5-dinitrophenyl)-1,2,4-oxadiazole is as follows: (1) Take 0.50g (2.2mmol) of dinitrobenzyl oxime and add it to 5mL (8.16g, 26.4mmol) of trichloroacetic anhydride under stirring conditions; (2) Heat the system to 90℃ and reflux for 1h; (3) Cool to room temperature, add 20mL of ice water, and a white solid precipitates; (4) Stir for 30min and filter, and dry to obtain 0.65g of white powder with a yield of 83.6%.

[0042] DSC (10℃·min) -1 ): 130℃ (mp); 13 C NMR (101MHz, DMSO-d6, 25℃) δ: 175.17, 166.68, 149.22, 128.11, 127.75, 122.14, 82.73. 1 H NMR(400MHz,DMSO)δ9.06(1H),9.02(2H).IR(KBr,ν / cm -1 ):3084(m),1555(m),1342(s),1168(w),1082(w),919(m),826(m),722(m).

[0043] Example 3 Synthesis of 5-amino-3-(3,5-dinitrophenyl)-1,2,4-oxadiazole

[0044] The specific synthesis method of 5-amino-3-(3,5-dinitrophenyl)-1,2,4-oxadiazole is as follows: (1) Take 40.00g of solid NaOH and add it to a three-necked flask. Then take 40mL of ammonia water to a constant pressure dropping funnel. Connect the safety bottle, drying bottle, reaction bottle and tail gas treatment device. Control the opening of the constant pressure dropping funnel and slowly drop the ammonia water into NaOH to prepare ammonia gas. (2) Take 0.50g (1.4mmol) of 5-trichloromethyl-3-(3,5-dinitrophenyl)-1,2,4-oxadiazole to a reaction flask, add 30mL of methanol, and place it in an ice bath at 0℃ and stir. (3) Pass excess ammonia gas through it in a slow bubbling manner. The white solid gradually dissolves. Continue bubbling for 3h. (4) Raise the reaction to room temperature to form a precipitate. (5) Filter and wash with a small amount of methanol to obtain 0.26g of yellowish-brown solid with a yield of 73.3%.

[0045] DSC (10℃·min) -1 ): 168℃ (mp); 13C NMR (101MHz, DMSO-d6, 25℃) δ: 173.20, 165.41, 149.08, 130.73, 126.73, 120.73. 1 H NMR(400MHz,DMSO)δ9.03(1H),8.97(2H),8.39(NH2,2H)IR(KBr,ν / cm -1 ):3421(m),1577(m),1340(s),1180(w),1081(w),910(m),768(m),732(m).

[0046] Example 4 Synthesis of 5-methylazido-3-(3,5-dinitrophenyl)-1,2,4-oxadiazole

[0047] The specific synthesis method of 5-methylazido-3-(3,5-dinitrophenyl)-1,2,4-oxadiazole is as follows: (1) 1.00 g (4.4 mmol) of dinitrobenzyl oxime was suspended in 40 mL of toluene; (2) 1.12 g (8.8 mmol, 2 eq.) of chloroacetyl chloride in 10 mL of toluene was added dropwise; (3) The mixture was heated to 110 °C and refluxed for 4 h; (4) The mixture was cooled to room temperature and the solvent was evaporated to obtain a white intermediate; (5) The white intermediate was dissolved in 30 mL of acetonitrile, and 0.20 g of NaN3 was added. The mixture was stirred at 55 °C for 10 h; (6) The mixture was cooled to room temperature, and the solution was placed on 20.00 g of ice and stirred for 20 min; (7) The mixture was filtered and dried to obtain 0.96 g of a pale yellow solid with a yield of 75.0%.

[0048] DSC (10℃·min) -1 ): 81.1℃ (mp); 13 C NMR (101MHz, DMSO-d6, 25℃) δ: 177.48, 165.81, 149.29, 128.94, 127.36, 124.61, 45.17. 1 H NMR(400MHz,DMSO)δ9.02(3H),5.09(CH2,2H)IR(KBr,ν / cm -1 ):3102(m),2114(s),1541(s),1351(s),1082(w),920(m).

[0049] Example 5 Synthesis of 5-methylhydroxy-3-(3,5-dinitrophenyl)-1,2,4-oxadiazole

[0050] The specific synthesis method of 5-methylazido-3-(3,5-dinitrophenyl)-1,2,4-oxadiazole is as follows: (1) Dissolve 1.00 g (4.4 mmol) of dinitrobenzylaminoxime in 50 mL of acetonitrile and add 0.62 g (1 eq.) of K2CO3; (2) Add 20 mL of acetonitrile solution of 0.65 g of acetoxyacetyl chloride dropwise to the dinitrobenzylaminoxime solution; (3) Heat to 83 °C and reflux for 3 h; (4) Cool to room temperature and evaporate the solvent; (5) Dilute the solid with 20 mL of water and extract with 60 mL of ethyl acetate, and collect the organic phase; (6) Dry the organic phase with anhydrous MgSO4 and evaporate to obtain a purple-black intermediate; (7) Dissolve the purple-black intermediate in 40 mL of methanol; (8) Add 0.10 g of K2CO3 to the solvent. K2CO3, heated to 65℃ and refluxed for 2h; (9) the solvent was evaporated, the solid was washed with a small amount of water and dried to obtain 0.71g of brownish-black solid, with a yield of 60.3%.

[0051] DSC (10℃·min) -1 ): 150℃ (mp); 13 C NMR (101MHz, DMSO-d6, 25℃) δ: 181.41, 165.55, 149.27, 129.28, 127.29, 121.44, 55.67. 1 H NMR(400MHz,DMSO)δ9.01(3H),6.21(OH,1H),4.90(CH2,2H).IR(KBr,ν / cm -1 ):3299(w),3091(w),1559(m),1340(m),1204(w),1084(m),917(m),783(w).

[0052] Table 1. Physicochemical and detonation properties of energetic compounds of 3-(3,5-dinitrophenyl)-1,2,4-oxadiazole class.

[0053]

[0054] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A class of low-sensitivity 3-(3,5-dinitrophenyl)-1,2,4-oxadiazole energetic compounds, characterized by a 3-(3,5-dinitrophenyl)-1,2,4-oxadiazole ring as the basic skeleton, with trifluoromethyl, trichloromethyl, methyl azido, and methyl hydroxyl groups as substituents, and their structural formulas are as follows:

2. The method for synthesizing 5-trifluoromethyl-3-(3,5-dinitrophenyl)-1,2,4-oxadiazole as described in claim 1, characterized in that: (1) At 0-40℃ with mechanical stirring, 3,5-dinitrobenzyl oxime was added to a certain amount of a mixed solution of trifluoroacetic anhydride and trifluoroacetic acid. (2) The system was heated to 90℃ and refluxed for 3-16 hours. (3) The system was cooled to room temperature and an appropriate amount of ice water was added to precipitate a white solid. (4) After stirring, the mixture was filtered and dried to obtain 5-trifluoromethyl-3-(3,5-dinitrophenyl)-1,2,4-oxadiazole.

3. The method for synthesizing 5-trifluoromethyl-3-(3,5-dinitrophenyl)-1,2,4-oxadiazole as described in claim 2, characterized in that: In step (1), the volume ratio of trifluoroacetic acid to trifluoroacetic anhydride is 0.1:1 to 1:1, and the molar ratio of trifluoroacetic anhydride to 3,5-dinitrobenzylaminoxime is 1:1 to 10:

1.

4. The method for synthesizing 5-trichloromethyl-3-(3,5-dinitrophenyl)-1,2,4-oxadiazole as described in claim 1, characterized in that: (1) At 0-40℃ with mechanical stirring, 3,5-dinitrobenzylaminoxime was added to a certain amount of trichloroacetic anhydride. (2) The system was heated to 90℃ and refluxed for 0.5-3h. (3) The system was cooled to room temperature and an appropriate amount of ice water was added to precipitate a white solid. (4) After stirring, the solid was filtered and dried to obtain 5-trichloromethyl-3-(3,5-dinitrophenyl)-1,2,4-oxadiazole.

5. The method for synthesizing 5-methylazido-3-(3,5-dinitrophenyl)-1,2,4-oxadiazole as described in claim 1, characterized in that: (1) 3,5-dinitrobenzyl oxime was suspended in a certain amount of toluene at 0-40℃ with mechanical stirring; (2) 2-3 equivalents of chloroacetyl chloride in toluene solution were added dropwise; (3) The mixture was heated to 110℃ and refluxed for 4-6 hours; (4) The mixture was cooled to room temperature and the solvent was evaporated to obtain a white intermediate; (5) The white intermediate was dissolved in a certain amount of acetonitrile, and 1-2 equivalents of NaN3 were added. The mixture was stirred at 55℃ for 8-12 hours; (6) The mixture was cooled to room temperature, and the solution was placed on ice water and stirred for 30 minutes; (7) The mixture was filtered and dried to obtain 5-methylazido-3-(3,5-dinitrophenyl)-1,2,4-oxadiazole product.

6. The method for synthesizing 5-methylhydroxy-3-(3,5-dinitrophenyl)-1,2,4-oxadiazole as described in claim 1, characterized in that: (1) Dissolve 3,5-dinitrobenzyl oxime in a certain amount of acetonitrile at 0-40℃ with mechanical stirring, and add 1-2 equivalents of K2CO3; (2) Add 1-1.5 equivalents of acetoxyacetyl chloride acetonitrile solution dropwise; (3) Heat to 83℃ and reflux for 3-6 h; (4) Cool to room temperature and evaporate the solvent; (5) Dilute the solid with a certain amount of water, extract with a certain amount of ethyl acetate, and collect the organic phase; (6) Dry the organic phase with anhydrous MgSO4 and evaporate to obtain a purplish-black intermediate; (7) Dissolve the purplish-black intermediate in a certain amount of methanol solvent; (8) Add 0.1-1 equivalents of K2CO3, heat to 65℃ and reflux for 2-4 h; (9) Evaporate the solvent, wash the solid with a small amount of water, and dry to obtain 5-methylhydroxy-3-(3,5-dinitrophenyl)-1,2,4-oxadiazole product.

7. The application of 5-trifluoromethyl-3-(3,5-dinitrophenyl)-1,2,4-oxadiazole and 5-methylazido-3-(3,5-dinitrophenyl)-1,2,4-oxadiazole as described in claim 1 in the field of cast-carrier explosives.

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