Novel imino-bridged pyrazole triazole energetic compound and preparation method thereof

Abstract

The invention discloses a novel imino-bridged pyrazole triazole energetic compound which is (5-nitro-N-(5-nitryl-1H-pyrazole-4-yl)-1H-1, 2, 4-triazole-3-amine) and (N-(3, 5-dinitro-1H-pyrazole-4-yl)-5-nitryl-1H-1, 2, 4-triazole-3-amine), and a preparation method of the novel imino-bridged pyrazole triazole energetic compound. The invention also discloses a preparation method of the novel imino-bridged pyrazole triazole energetic compound. The novel imino-bridged energetic compound is obtained by bridging an imino group to construct a basic skeleton and carrying out energetic derivation on the basis of the basic skeleton. The prepared compound is novel in structure and excellent in comprehensive performance, and has huge application potential in the field of high-energy insensitive explosives.

Description

Technical Field

[0001] This invention relates to bridging energetic compounds and their preparation methods, specifically to a novel imino-bridged pyrazole triazole energetic compound and its preparation method, belonging to the field of energetic material preparation technology. Background Technology

[0002] The triazole framework consists of two carbon atoms and three nitrogen atoms. Compared to tetraazoles, which have a higher nitrogen content, triazoles are more stable and have more modifiable sites, allowing for the introduction of more energetic groups. Compared to pyrazoles, which have a higher carbon content, the higher nitrogen content gives the triazole framework better energy performance. Therefore, the triazole framework can well balance energy and sensitivity, making it a preferred framework for constructing novel low-sensitivity, high-energy explosive molecules.

[0003] Pyrazole nitrogen heterocycles are five-membered heterocycles composed of two nitrogen atoms and three carbon atoms. The ring has many modifiable sites. Even after constructing a ring skeleton, it can still provide two reaction sites for energetic modification. Furthermore, pyrazole compounds usually have good detonation performance and thermal stability, making them a structural unit with the potential to construct low-sensitivity high-energy explosives.

[0004] The introduction of imino groups leads to molecular interconnections via hydrogen bonds centered on the imino group, forming a rich three-dimensional hydrogen bond network. This abundant hydrogen bonding enhances the packing efficiency and density of the compound crystals, thereby improving its final energy performance. Simultaneously, the strong hydrogen bond network can also mitigate external stimuli and reduce sensitivity through hydrogen bond interactions.

[0005] Combining the advantages of these three elements, selecting imine as the bridging structure and triazole and pyrazole as structural units to construct a novel energetic framework, and then deriving from it to obtain imine-bridged explosive molecules, is an effective method for constructing low-sensitivity high-energy explosives. Summary of the Invention

[0006] The purpose of this invention is to provide a novel energetic compound of imino-bridged pyrazole triazole.

[0007] This invention is implemented as follows:

[0008] A novel energetic compound of imino-bridged pyrazole-triazole has the following structural formula:

[0009] .

[0010] Another object of the present invention is to provide a method for preparing a novel energetic compound of imino-bridged pyrazole-triazole, the reaction formula of which is as follows:

[0011] .

[0012] Specifically, the present invention provides a method for preparing a novel energetic compound of imino-bridged pyrazole triazole, comprising:

[0013] Step 1: Synthesis of Intermediate 1

[0014] At room temperature, 4-aminopyrazole and N-cyanodithioimine dimethyl carbonate were dispersed in a solvent in sequence. After thorough stirring, a small amount of organic base was added, and the reaction was continued at room temperature for 8 hours. After the reaction was completed, the solid was collected by filtration, washed several times with solvent, and dried to obtain intermediate 1.

[0015] The reaction in step one can be carried out in ethanol, but methanol or other solvents can also be used. Triethylamine can be used for the reaction, but other organic bases such as pyridine or piperidine can also be used.

[0016] Step 2: Synthesis of Intermediate 2

[0017] Under ice bath conditions, intermediate 1 was dispersed in anhydrous ethanol. While stirring, hydrazine hydrate was slowly added to the solution. After the addition was complete, the mixture was slowly heated under reflux. After the reaction was complete and the system cooled to room temperature, the solid was collected by filtration to obtain intermediate 2.

[0018] Step 3: Synthesis of Compound 1

[0019] Under ice bath conditions, intermediate 2 was dispersed in concentrated nitric acid and stirred thoroughly. A small amount of water was added and stirring continued. Then, sodium nitrite solution was slowly added dropwise to the reaction mixture. After the addition was complete, the reaction continued in the ice bath. After the ice bath reaction was completed, the reaction solution was added dropwise to excess sodium nitrite solution to continue the reaction. After the reaction was completed, the mixture was filtered, and the filtrate was extracted several times with ethyl acetate. The solvent was removed by rotary evaporation and then dried to obtain compound 1, namely: (5-nitro-N-(5-nitro-1H-pyrazol-4-yl)-1H-1,2,4-triazol-3-amine).

[0020] Step 4: Synthesis of Compound 2

[0021] Compound 1 was slowly dissolved in concentrated sulfuric acid and cooled in an ice bath. Fuming nitric acid was then slowly added dropwise to the solution. After the addition was complete, the reaction was continued in an ice bath. After the reaction was complete, the reaction solution was poured into ice water, extracted several times with ethyl acetate, and the solvent was removed by rotary evaporation. After drying, compound 2 was obtained, namely: (N-(3,5-dinitro-1H-pyrazol-4-yl)-5-nitro-1H-1,2,4-triazol-3-amine).

[0022] This invention provides a method for preparing novel energetic compounds with imino-bridged pyrazole triazoles. The method utilizes imino groups to construct a basic framework, and then performs energetic derivatization on this framework to obtain novel imino-bridged energetic compounds. The compounds prepared by this invention have novel structures and excellent overall performance, showing great application potential in the field of high-energy insensitive explosives. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 The crystal structure of compound 1 prepared according to one embodiment of the present invention is shown below.

[0025] Figure 2 The crystal structure of compound 2 prepared in one embodiment of the present invention is shown. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be described in detail below. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other implementation methods obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0027] Example 1

[0028] The following examples provide various methods for synthesizing compound 1, including:

[0029] Step 1: Synthesis of Intermediate 1

[0030] Scheme 1: At room temperature, 4-aminopyrazole (0.83 g, 0.01 mol) and N-cyanodithioimine dimethyl carbonate (1.46 g, 0.01 mol) were dispersed in 10 mL of anhydrous ethanol. After thorough stirring, triethylamine (0.2 mL) was added dropwise, and the reaction was continued at room temperature for 8 hours. After the reaction was completed, the solid was collected by filtration and washed several times with anhydrous ethanol before drying to obtain purple-gray intermediate 1.

[0031] Scheme 2: At room temperature, 4-aminopyrazole (0.83 g, 0.01 mol) and N-cyanodithioimine dimethyl carbonate (1.46 g, 0.01 mol) were dispersed in 10 mL of tetrahydrofuran. After thorough stirring, triethylamine (0.2 mL) was added dropwise, and the reaction was continued at room temperature for 8 hours. After the reaction was completed, the solid was collected by filtration and washed several times with anhydrous ethanol before drying to obtain purple-gray intermediate 1.

[0032] Scheme 3: At room temperature, 4-aminopyrazole (0.83 g, 0.01 mol) and N-cyanodithioimine dimethyl carbonate (1.46 g, 0.01 mol) were dispersed in 10 mL of anhydrous ethanol. After thorough stirring, triethylamine (0.2 mL) was added dropwise. The reaction was carried out at 40 degrees Celsius for 8 hours. After the reaction was completed, the solid was collected by filtration and washed several times with anhydrous ethanol before drying to obtain a purple-gray intermediate 1.

[0033] Scheme 4: At room temperature, 4-aminopyrazole (0.83 g, 0.01 mol) and N-cyanodithioimine dimethyl carbonate (1.46 g, 0.01 mol) were dispersed in 10 mL of DMF in sequence. After thorough stirring, potassium carbonate (0.2 mL) was added dropwise. The reaction was carried out at 40 degrees Celsius for 8 hours. After the reaction was completed, the solid was collected by filtration and washed several times with anhydrous ethanol before drying to obtain purple-gray intermediate 1.

[0034] Step 2: Synthesis of Intermediate 2

[0035] Scheme 1: Under ice bath conditions, intermediate 1 (1.81 g, 0.01 mol) was dispersed in 10 mL of anhydrous ethanol. While stirring, hydrazine hydrate (0.1 g, 0.02 mol) was slowly added to the solution. After the addition was complete, the mixture was slowly heated under reflux for 8 hours. After the reaction was complete, the heating was removed, and the system was allowed to cool to room temperature. The solid was collected by filtration, washed several times with petroleum ether, and then dried to obtain purplish-gray intermediate 2.

[0036] Option 2: Under ice bath conditions, intermediate 1 (1.81 g, 0.01 mol) was dispersed in 10 mL of anhydrous ethanol. While stirring, hydrazine hydrate (0.1 g, 0.02 mol) was slowly added to the solution. After the addition was complete, the mixture was allowed to react slowly at room temperature for 8 hours. After the reaction was complete, the heating was removed, and the system was allowed to cool to room temperature. The solid was collected by filtration, washed several times with petroleum ether, and then dried to obtain purplish-gray intermediate 2.

[0037] Scheme 3: Under ice bath conditions, intermediate 1 (1.81 g, 0.01 mol) was dispersed in 10 mL of anhydrous methanol, tetrahydrofuran, and DMF. While stirring, hydrazine hydrate (0.1 g, 0.02 mol) was slowly added to the solution. After the addition was complete, the mixture was slowly heated under reflux for 8 hours. After the reaction was complete, the heating was removed, and the system was allowed to cool to room temperature. The solid was collected by filtration, washed several times with petroleum ether, and then dried to obtain purplish-gray intermediate 2.

[0038] Option 4: Under ice bath conditions, intermediate 1 (1.81 g, 0.01 mol) was dispersed in 10 mL of anhydrous methanol, tetrahydrofuran, and DMF. While stirring, hydrazine hydrochloride (1.37 g, 0.02 mol) was slowly added to the solution. After the addition was complete, the mixture was slowly heated under reflux for 8 hours. After the reaction was complete, the heating was removed, and the system was allowed to cool to room temperature. The solid was collected by filtration, washed several times with petroleum ether, and then dried to obtain a purplish-gray intermediate 2.

[0039] Step 3: Synthesis of Compound 1

[0040] Under ice bath conditions, intermediate 2 (0.17 g, 0.001 mol) was dispersed in concentrated nitric acid (70%, 2.5 mL). After stirring for ten minutes, water (0.75 mL) was added dropwise, and stirring continued for another ten minutes. Sodium nitrite (0.17 mg, 1.60 mmol) was dissolved in water (0.25 mL) to prepare a sodium nitrite solution, which was slowly added dropwise to the reaction mixture. After the addition was complete, the reaction was continued under ice bath conditions for 1 hour. After the ice bath reaction was complete, the reaction mixture was added dropwise to the sodium nitrite solution (4.00 g sodium nitrite and 40 mL water). After the addition was complete, the temperature was raised to 40 °C and the reaction was carried out for 3 hours. After the reaction was complete, the system was cooled to room temperature, filtered, and the filtrate was extracted several times with ethyl acetate. The solvent was removed by rotary evaporation, and the filtrate was dried to obtain compound 1, the crystal structure of which is shown in the attached figure. Figure 1 As shown.

[0041] Example 2

[0042] This embodiment provides a method for synthesizing compound 2, including:

[0043] Compound 1 (0.24 g, 0.001 mol) was slowly added to 2 mL of concentrated sulfuric acid. After complete dissolution, the solution was transferred to an ice bath and cooled to below 5 °C. Then, 0.50 mL of fuming nitric acid was slowly added dropwise, paying attention to the rate of addition and maintaining the reaction temperature below 5 °C. After the addition was complete, the reaction was continued in an ice bath for 10 minutes. The reaction solution was then poured into 20 mL of ice water, extracted several times with ethyl acetate, and the solvent was removed by rotary evaporation. After drying, compound 2 was obtained, and its crystal structure is shown in the attached figure. Figure 2 As shown.

[0044] The physicochemical and detonation properties of compounds 1 and 2 prepared in the embodiments of the present invention are analyzed, as shown in the table below:

[0045] Table 1. Physicochemical and detonation properties of imine-bridged pyrazole-triazole explosives

[0046] Compd. <![CDATA[T d a [℃]]]> <![CDATA[ρ b [g·cm -3 ]]]> <![CDATA[Δ f H c [kJ·mol -1 ]]]> <![CDATA[D d [m·s -1 ]]]> <![CDATA[P e [GPa]]]> <![CDATA[IS f [J]]]> <![CDATA[FS g [N]]]> 1 243 1.82 310.54 8445 28.9 16 144 2 205 1.86 364.04 8663 31.9 13 120 TNT 295 1.65 -67.0 6881 19.5 15 353 RDX 210 1.80 70.3 8795 34.9 7.4 120

[0047] As shown in the table above, the compounds 1 and 2 prepared in the embodiments of this invention have the following characteristics: Compound 1 has an enthalpy of formation of 310.54 kJ·mol⁻¹, and its theoretically calculated detonation velocity and detonation pressure are 8445 m·s⁻¹ and 28.9 GPa, respectively. After further introducing a nitro group, the enthalpy of formation of Compound 2 increases to 364.04 kJ·mol⁻¹, and the theoretically calculated detonation velocity and detonation pressure also increase to 8663 m·s⁻¹ and 31.9 GPa, respectively, falling between those of TNT (6881 m·s⁻¹ / 19.5 GPa) and RDX (8795 m·s⁻¹ and 34.9 GPa). Compared with other common explosives, it exhibits a better balance between energy and safety.

[0048] 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 variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims. It should also be noted that the various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the present invention will not describe the various possible combinations separately. Furthermore, various different embodiments of the present invention can also be arbitrarily combined, as long as they do not violate the spirit of the present invention, they should also be considered as the content disclosed in the present invention.

Claims

1. A novel energetic compound containing imino-bridged pyrazole triazole, characterized in that: It has one or two of the following structural formulas: 。 2. A method for preparing a novel energetic compound of imino-bridged pyrazole-triazole, characterized in that, The reaction formula is as follows: 。 3. The method for preparing the novel energetic compound of imino-bridged pyrazole-triazole according to claim 2, characterized in that... include: Step 1: Synthesis of Intermediate 1 At room temperature, 4-aminopyrazole and N-cyanodithioimine dimethyl carbonate were dispersed in a solvent in sequence. After thorough stirring, a small amount of organic base was added, and the reaction was continued at room temperature for 8 hours. After the reaction was completed, the solid was collected by filtration and washed several times with solvent before drying to obtain intermediate 1. Step 2: Synthesis of Intermediate 2 Under ice bath conditions, intermediate 1 was dispersed in anhydrous ethanol. While stirring, hydrazine hydrate was slowly added to the solution. After the addition was complete, the mixed solution was slowly heated to reflux for reaction. After the reaction was complete, the system was cooled to room temperature, and the solid was collected by filtration to obtain intermediate 2. Step 3: Synthesis of Compound 1 Under ice bath conditions, intermediate 2 was dispersed in concentrated nitric acid and stirred thoroughly. A small amount of water was added and stirring continued. Then, sodium nitrite solution was slowly added dropwise to the reaction mixture. After the addition was complete, the reaction continued in the ice bath. After the ice bath reaction was completed, the reaction solution was added dropwise to excess sodium nitrite solution to continue the reaction. After the reaction was completed, the mixture was filtered, and the filtrate was extracted several times with ethyl acetate. The solvent was removed by rotary evaporation and then dried to obtain compound 1, namely: (5-nitro-N-(5-nitro-1H-pyrazol-4-yl)-1H-1,2,4-triazol-3-amine). Step 4: Synthesis of Compound 2 Compound 1 was slowly dissolved in concentrated sulfuric acid and cooled in an ice bath. Fuming nitric acid was then slowly added dropwise to the solution. After the addition was complete, the reaction was continued in an ice bath. After the reaction was complete, the reaction solution was poured into ice water, extracted several times with ethyl acetate, and the solvent was removed by rotary evaporation. After drying, compound 2 was obtained, namely: (N-(3,5-dinitro-1H-pyrazol-4-yl)-5-nitro-1H-1,2,4-triazol-3-amine).

4. The method for preparing the novel energetic compound of imino-bridged pyrazole-triazole according to claim 3, characterized in that... include: In step one, the solvent is anhydrous ethanol or methanol; The organic base is triethylamine, pyridine, or piperidine.

Images