3-(4-nitrofuran-3-yloxymethyl)-3-azidomethyloxetane

Abstract

This invention discloses a method for preparing 3-(4-nitrofuran-3-oxomethyl)-3-azidomethyloxetane. The method involves reacting 3,3-dibromomethyloxetane with sodium azide under mild conditions to obtain the intermediate 3-bromomethyl-3-azidomethyloxetane, which is then reacted with 3-nitro-4-hydroxyfuran in an inexpensive and environmentally friendly inorganic alkaline solvent system under heating in the presence of a catalytic amount of phase transfer catalyst to obtain the target product. The product of this invention possesses excellent detonation performance and desensitizing properties, while also functioning as a liquid phase carrier for cast explosives, a monomer plasticizer, and a single-element explosive. It can also be polymerized for use as a structural energetic material or an energetic binder, demonstrating considerable application potential.

Description

Technical Field

[0001] This invention belongs to the field of insensitive energetic materials and relates to a method for preparing 3-(4-nitrofuran-3-oxomethyl)-3-azidomethyloxetane. Background Technology

[0002] Modular energetic materials refer to energetic materials that are mass-produced and manufactured in series based on standardization. They can be combined with other units through different processing methods to form products with relatively independent functions, and are decomposable, recombinable, and interchangeable. They can be given a wide range of applications through reasonable structural design to meet the needs of different weapon systems, and can also achieve mass production and large-scale production through standardized methods. This is one of the main future development directions in the field of energetic materials. Research on the design, customization, and synthesis of modular energetic materials has recently received considerable attention.

[0003] Oxycyclobutane, as a saturated four-membered ring ether monomer with dual active sites, can simultaneously load two energetic groups to form a polymer backbone, representing an important branch of energetic polymers with broad application prospects. Furazan compounds differ from traditional energetic compounds. On one hand, their molecular structure contains numerous CN, C=N, and N=N bonds, resulting in a high enthalpy of formation. Furthermore, the aromaticity of the furazan ring enhances the thermal stability of furazan derivatives, and the coplanarity of the furazan ring contributes to their high density. On the other hand, due to the high electronegativity of nitrogen and oxygen atoms, furazan compounds' nitrogen-heteroaromatic ring system can form benzene-like large π bonds, exhibiting insensitive and thermally stable properties. Therefore, many furazan energetic derivatives possess advantages such as high energy density, high standard enthalpy of formation (ΔHf), high nitrogen content, and excellent heat resistance. The excellent mechanical properties of oxycyclobutane polymers and the stable furazan-based energetic groups perfectly match the application requirements of modular energetic materials.

[0004] Compared to the insufficient production capacity of traditional high-precision munitions, modular energetic materials, through computer-aided innovative molecular structure design, have yielded an energetic compound with nitrogen- and oxo-butane structures. This compound possesses excellent detonation performance and insensitive properties, while also functioning as a liquid-phase carrier in cast explosives, a monomeric plasticizer, and a single-element explosive. It can also be polymerized for use as a structural energetic material or an energetic binder—a novel multifunctional insensitive energetic material. As a completely new concept in energetic materials, modular multifunctional energetic materials can be mass-produced in peacetime and then differentiated according to battlefield requirements to obtain various weapons and munitions that meet specific needs. It has broad research prospects, and its application research is urgently needed. For example, the paper "Furazanyl Ethers of Pentaerythritol Derivatives" in *Int Annu Conf ICT 28th*, 1997, 127:176356, discloses a method for preparing 3,3-bis(4-nitrofurazan-3-oxomethyl)oxetane. This energetic monomer contains a furazan group and an oxetane monomer, exhibiting high energy density and promising application as a multifunctional modular energetic material. However, the oxetane ring carries two large side groups symmetrically distributed, leading to a sharp increase in monomer crystallization tendency and severely affecting subsequent polymerization processes. This results in the inability to obtain polymers that meet application standards, hindering practical application. Therefore, designing an energetic furazan-substituted oxetane compound that retains the high-energy insensitivity of 3,3-bis(4-nitrofurazan-3-oxomethyl)oxetane while overcoming the performance defects caused by its highly symmetrical structure holds considerable application potential. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a method for preparing 3-(4-nitrofurazan-3-oxomethyl)-3-azidomethyloxetane, which contains energetic furazan-substituted oxetane compounds that can retain high-energy insensitive properties while overcoming the performance defects caused by highly symmetrical structures.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0007] A method for preparing 3-(4-nitrofuran-3-oxomethyl)-3-azidomethyloxetane includes the following steps:

[0008] Step 1: Add the azidating agent and 3,3-dibromomethyloxetane to a polar aprotic solvent and stir the reaction at 45-85℃ for 0.5-2 hours. Then, extract, wash with water, dry, filter, and evaporate the solvent to obtain the intermediate 3-azidomethyl-3-bromomethyloxetane.

[0009] Step 2: The intermediates 3-azidomethyl-3-bromomethyloxetane and 3-nitro-4-hydroxyfurazan obtained in Step 1 are added to a polar aprotic solvent and stirred at 45-85°C for 0.5-2 hours. Then, after extraction, washing with water, drying, filtration, and evaporation of the solvent, 3-(4-nitrofurazan-3-oxomethyl)-3-azidomethyloxetane is obtained.

[0010] The present invention also includes the following technical features:

[0011] Specifically, the azide reagent is sodium azide, trimethyl azidosilane, p-toluenesulfonyl azide, ethyl azide, tetrabutylammonium azide, or tri-n-butyltin azide.

[0012] Specifically, the molar ratio of 3,3-dibromomethyloxetane to the azide reagent is 1:(0.8-1.2).

[0013] Specifically, the alkaline donor is anhydrous potassium carbonate, cesium carbonate, or ferric hydroxide.

[0014] Specifically, the phase transfer catalyst is tetrabutylammonium bromide, benzyltriethylammonium chloride, methyltrialkylammonium chloride, or 18-crown ether-6.

[0015] Specifically, the molar ratio of the intermediate 3-azidomethyl-3-bromomethyloxetane, 3-nitro-4-hydroxyfurazan, the basic donor, and the phase transfer catalyst is 1:(1-2):(1-2):0.02.

[0016] Specifically, the polar aprotic solvent is DMF, MeCN, Acetone, or DMSO.

[0017] Compared with the prior art, the present invention has the following technical effects:

[0018] 1. This invention uses commercially available 3,3-dibromomethyloxetane as a raw material. Under mild conditions, an azide reaction is carried out to obtain the reaction intermediate 3-bromomethyl-3-azidomethyloxetane. This intermediate is then heated with readily available 3-nitro-4-hydroxyfurazan in an inexpensive and environmentally friendly potassium carbonate alkaline system to obtain 3-(4-nitrofurazan-3-oxomethyl)-3-azidomethyloxetane. This method has the advantages of readily available raw materials, mild reaction conditions, safety, and environmental friendliness. Furthermore, the reaction steps are simple, allowing for continuous operation and facilitating industrial-scale continuous production.

[0019] 2. The 3-(4-nitrofuran-3-oxomethyl)-3-azidomethyloxacyclobutane obtained by the synthesis method of the present invention is a novel multifunctional non-sensitive energetic material that has good detonation performance and insensitive properties, while also acting as a liquid carrier for cast explosives, a monomer plasticizer, and a single explosive. It can also be polymerized and used as a structural energetic material or an energetic binder. Moreover, the product exists in a liquid state at room temperature, and subsequent polymerization tests show that its polymer has excellent mechanical properties.

[0020] 3. The 3-(4-nitrofuran-3-oxomethyl)-3-azidomethyloxetane obtained by the synthesis method of the present invention can significantly improve its compatibility by introducing multiple energetic groups into the same energetic monomer through molecular structure design, making it more conducive to practical applications. Attached Figure Description

[0021] Figure 1 The 1H NMR spectrum of 13-(4-nitrofuran-3-oxomethyl)-3-azidomethyloxetane;

[0022] Figure 2 The carbon NMR spectrum of 3-(4-nitrofuran-3-oxomethyl)-3-azidomethyloxetane;

[0023] Figure 3 The FTIR spectrum of 3-(4-nitrofuran-3-oxomethyl)-3-azidomethyloxetane;

[0024] Figure 4 High-resolution mass spectrum of 3-(4-nitrofuran-3-oxomethyl)-3-azidomethyloxetane;

[0025] Figure 5 The DSC diagram for 3-(4-nitrofuran-3-oxomethyl)-3-azidomethyloxetane. Detailed Implementation

[0026] This invention involves reacting commercially available 3,3-dibromomethyloxetane with a measured amount of sodium azide under mild conditions to obtain the intermediate 3-bromomethyl-3-azidomethyloxetane. The target product is then obtained by heating with readily available 3-nitro-4-hydroxyfuran in an inexpensive and environmentally friendly inorganic alkaline solvent system in the presence of a catalytic amount of phase transfer catalyst. The synthetic route is shown below:

[0027]

[0028] The method includes the following steps:

[0029] Step 1: Add the azidating agent and 3,3-dibromomethyloxetane to a polar aprotic solvent and stir the reaction at 45-85℃ for 0.5-2 hours. Then, extract, wash with water, dry, filter, and evaporate the solvent to obtain the intermediate 3-azidomethyl-3-bromomethyloxetane.

[0030] Step 2: Add the intermediate 3-azidomethyl-3-bromomethyloxetane obtained in Step 1, 3-nitro-4-hydroxyfurazan, the basic donor and the phase transfer catalyst to a polar aprotic solvent, and stir the reaction at 45-85℃ for 0.5-2h. Then, after extraction, washing with water, drying, filtering and evaporating the solvent, 3-(4-nitrofurazan-3-oxomethyl)-3-azidomethyloxetane is obtained.

[0031] The azide reagents in step 1 include sodium azide, trimethyl azidosilane, p-toluenesulfonyl azide, ethyl azide, tetrabutylammonium azide, and tri-n-butyltin azide.

[0032] In step 1, the molar ratio of 3,3-dibromomethyloxetane to the azide reagent is 1:(0.8-1.2).

[0033] Step 2: The alkaline donors include anhydrous potassium carbonate, cesium carbonate, and ferric hydroxide.

[0034] The phase transfer catalyst in step 2 includes tetrabutylammonium bromide, benzyltriethylammonium chloride, methyltrialkylammonium chloride, and 18-crown ether-6.

[0035] The molar ratio of intermediate 3-azidomethyl-3-bromomethyloxetane, 3-nitro-4-hydroxyfurazan, basic donor and phase transfer catalyst in step 2 is 1:(1~2):(1~2):0.02.

[0036] Polar aprotic solvents include DMF, MeCN, Acetone, and DMSO.

[0037] The following are specific embodiments of the present invention. It should be noted that the present invention is not limited to the following specific embodiments. All equivalent modifications made based on the technical solutions of this application fall within the protection scope of the present invention.

[0038] Example 1:

[0039] This embodiment provides a method for preparing 3-(4-nitrofuran-3-oxomethyl)-3-azidomethyloxetane, comprising the following steps:

[0040] Step 1: 3,3-Dibromomethyloxetane (2.44 g, 0.01 mol) and sodium azide (0.65 g, 0.01 mol) were added to 3 ml of DMF at room temperature and stirred thoroughly. The mixture was reacted at 60 °C for 1.5 h. After the reaction was completed, water and ethyl acetate were added for extraction, washed with water, dried with anhydrous magnesium sulfate, filtered and evaporated to dryness to finally obtain yellow oily 3-azidomethyl-3-bromomethyloxetane (1.98 g, yield 96%) as an intermediate.

[0041] Step 2: The intermediate obtained in Step 1 (2.06 g, 0.01 mol), 3-nitro-4-hydroxyfurazan (2.62 g, 0.02 mol), anhydrous potassium carbonate (2.76 g, 0.02 mol), and phase transfer catalyst 18-crown ether-6 (0.05 g, 0.0002 mol) were added to dimethylformamide DMF (30 ml) at room temperature and stirred thoroughly. The mixture was reacted at 75 °C for 1.5 h. After the reaction was completed, water and dichloromethane were added for extraction. The product was then washed with water, dried over anhydrous magnesium sulfate, filtered, and the solvent was evaporated to obtain the final yellow oily target product (2.14 g, yield 83.5%).

[0042] Structural assessment:

[0043] (1) Carbon nuclear magnetic resonance spectroscopy analysis

[0044] The obtained oily product was analyzed by carbon nuclear magnetic resonance spectroscopy as follows: Figure 2 As shown, the characteristic peaks of nitrofuran at 158.79 ppm and 152.79 ppm did not shift, and the peak shape remained the characteristic high-low peak pattern of nitrofuran, indicating that the furazan nitro group still exists. The characteristic peaks of methyloxetane at 74.94 ppm, 74.15 ppm, and 43.37 ppm did not change much, shifting to 74.28 ppm, 74.14 ppm, and 42.76 ppm respectively, indicating that the methyloxetane body remained unchanged. Correspondingly, the carbon spectrum peak of bromomethyl at 36.44 ppm shifted to a lower field to 52.65 ppm, indicating that bromomethyl was converted into the more electronegative (weaker shielding effect) azidomethyl group. The proton spectrum is shown below. Figure 1 As shown, the area obtained by integrating the corresponding peaks is 1:2:1, which also confirms the successful synthesis of 3-(4-nitrofuran-3-oxomethyl)-3-azidomethyloxetane.

[0045] (2) Infrared spectral analysis

[0046] The obtained spectrum is as follows Figure 3As shown, the characteristic peak of 3,3-dibromomethyloxetane at 835 cm⁻¹ still exists, indicating that the oxetane structure still exists in the pure monomer; the nitro infrared absorption peak at 1624 cm⁻¹ also still exists, indicating that the product still contains nitro; and the appearance of the characteristic absorption peaks of azido group at 2100 cm⁻¹ and 2150 cm⁻¹ indicates the successful synthesis of 3-(4-nitrofuran-3-oxomethyl)-3-azidomethyloxetane.

[0047] (3) High-resolution mass spectrometry analysis

[0048] The obtained pale yellow crystals were analyzed by high-resolution mass spectrometry as follows: Figure 4 As shown, the highest peak in the obtained spectrum (257.06735) is completely consistent with the predicted molecular weight of the hydrogenated structure (257.0634), indicating the successful synthesis of 3-(4-nitrofuran-3-oxomethyl)-3-azidomethyloxetane.

[0049] like Figure 5 As shown in Table 1, the key parameters of energetic materials such as density, detonation performance, stability, and oxygen balance of the present invention have been significantly improved. At the same time, it can overcome the performance defects caused by the highly symmetrical structure and has considerable application prospects.

[0050] Table 1. Comparison of density, detonation velocity, and sensitivity of 3-(4-nitrofuran-3-oxomethyl)-3-azidomethyloxetane and BAMO

[0051]

[0052] Example 2:

[0053] This embodiment provides a method for preparing 3-(4-nitrofuran-3-oxomethyl)-3-azidomethyloxetane. The preparation method and steps of this embodiment are the same as those of Example 1, except that: in step 1, the amount of sodium azide added is 0.78 g (0.012 mol), and 2.00 g (yield 97%) of yellow oily 3-azidomethyl-3-bromomethyloxetane is obtained as an intermediate; in step 2, 1.31 g (0.01 mol) of 3-nitro-4-hydroxyfuran and 1.88 g (0.01 mol) of anhydrous potassium carbonate are added, the reaction time is 1.2 h, and the final oily product 3-(4-nitrofuran-3-oxomethyl)-3-azidomethyloxetane obtained in step 2 is 2.2 g, with a yield of 85.8%.

[0054] The structural identification results in this embodiment are the same as those in Embodiment 1.

[0055] Example 3:

[0056] This embodiment provides a method for preparing 3-(4-nitrofuran-3-oxomethyl)-3-azidomethyloxetane. The preparation method and steps of this embodiment are the same as those of Example 1, except that: in step 1, the amount of sodium azide added is (0.52 g, 0.008 mol), the reaction time is 1 h, and the yellow oily 3-azidomethyl-3-bromomethyloxetane (1.69 g, yield 82%) is obtained as an intermediate; in step 2, the amount of 3-nitro-4-hydroxyfuran added is 1.31 g, 0.01 mol, and the amount of anhydrous potassium carbonate added is 3.96 g, 0.02 mol, the reaction time is 1.2 h, and the final oily product 3-(4-nitrofuran-3-oxomethyl)-3-azidomethyloxetane obtained in step 2 is 2.22 g, with a yield of 86.5%.

[0057] The structural identification results in this embodiment are the same as those in Embodiment 1.

[0058] Example 4:

[0059] This embodiment provides a method for preparing 3-(4-nitrofuran-3-oxomethyl)-3-azidomethyloxetane. The preparation method and steps of this embodiment are the same as those of Example 1, except that: in step 1, the reaction temperature is 80°C and the reaction time is 0.5 h, yielding 1.70 g of yellow oily 3-azidomethyl-3-bromomethyloxetane as an intermediate (yield 82.4%); in step 2, the amount of 3-nitro-4-hydroxyfuran added is 1.31 g (0.01 mol), the reaction temperature is 60°C, and the reaction time is 2 h, resulting in 1.88 g of the final oily product 3-(4-nitrofuran-3-oxomethyl)-3-azidomethyloxetane obtained in step 2 (yield 73.5%).

[0060] The structural identification results in this embodiment are the same as those in Embodiment 1.

[0061] Example 5:

[0062] This embodiment provides a method for preparing 3-(4-nitrofuran-3-oxomethyl)-3-azidomethyloxetane. The preparation method and steps in this embodiment are the same as those in Example 1, except that in step 2, the amount of 3-nitro-4-hydroxyfuran added is 1.31 g (0.01 mol), the amount of anhydrous potassium carbonate added is 1.88 g (0.01 mol), and the solvent used is 10 mL of DMSO. The final oily product 3-(4-nitrofuran-3-oxomethyl)-3-azidomethyloxetane obtained in step 2 is 1.97 g, with a yield of 76.5%.

[0063] The structural identification results in this embodiment are the same as those in Embodiment 1.

[0064] Example 6:

[0065] This embodiment provides a method for preparing 3-(4-nitrofuran-3-oxomethyl)-3-azidomethyloxetane. The preparation method and steps of this embodiment are the same as those of Example 1, except that: in step 1, the reaction temperature is 45°C and the reaction time is 2 hours, yielding 1.42 g of yellow oily 3-azidomethyl-3-bromomethyloxetane as an intermediate (yield 70.1%); in step 2, the amount of 3-nitro-4-hydroxyfuran added is 1.31 g (0.01 mol), and the amount of anhydrous potassium carbonate added is 1.88 g (0.01 mol), and the reaction temperature is 45°C. Finally, the final oily product 3-(4-nitrofuran-3-oxomethyl)-3-azidomethyloxetane obtained in step 2 is 1.74 g, with a yield of 67.8%.

[0066] The structural identification results in this embodiment are the same as those in Embodiment 1.

[0067] Example 7:

[0068] This embodiment provides a method for preparing 3-(4-nitrofuran-3-oxomethyl)-3-azidomethyloxetane. The preparation method and steps in this embodiment are the same as those in Example 1, except that in step 2, the amount of 3-nitro-4-hydroxyfuran added is 1.31 g (0.01 mol), the amount of anhydrous potassium carbonate added is 1.88 g (0.01 mol), and the selected phase transfer catalyst is tetrabutylammonium bromide (TBAB) (0.07 g (0.0002 mol)). The final oily product 3-(4-nitrofuran-3-oxomethyl)-3-azidomethyloxetane obtained in step 2 is 1.88 g, with a yield of 73.4%.

[0069] The structural identification results in this embodiment are the same as those in Embodiment 1.

Claims

1. A method for preparing 3-(4-nitrofuran-3-oxomethyl)-3-azidomethyloxetane, characterized in that, Includes the following steps: Step 1: Add the azidating agent and 3,3-dibromomethyloxetane to a polar aprotic solvent and stir the reaction at 45~85℃ for 0.5~2 h. Then, extract, wash with water, dry, filter, and evaporate the solvent to obtain the intermediate 3-azidomethyl-3-bromomethyloxetane. Step 2: The intermediate 3-azidomethyl-3-bromomethyloxetane, 3-nitro-4-hydroxyfurazan, the basic donor, and the phase transfer catalyst obtained in Step 1 are added to a polar aprotic solvent and stirred at 45~85℃ for 0.5~2 h. Then, after extraction, washing with water, drying, filtration, and evaporation of the solvent, 3-(4-nitrofurazan-3-oxomethyl)-3-azidomethyloxetane is obtained. The basic donor is anhydrous potassium carbonate, cesium carbonate, or iron hydroxide.

2. The method for preparing 3-(4-nitrofuran-3-oxomethyl)-3-azidomethyloxetane as described in claim 1, characterized in that, The azide reagent is sodium azide, trimethyl azidosilane, p-toluenesulfonyl azide, ethyl azide, tetrabutylammonium azide, or tri-n-butyltin azide.

3. The method for preparing 3-(4-nitrofuran-3-oxomethyl)-3-azidomethyloxetane as described in claim 1, characterized in that, The molar ratio of 3,3-dibromomethyloxetane to the azidating agent is 1:(0.8~1.2).

4. The method for preparing 3-(4-nitrofuran-3-oxomethyl)-3-azidomethyloxetane as described in claim 1, characterized in that, The phase transfer catalyst is tetrabutylammonium bromide, benzyltriethylammonium chloride, methyltrialkylammonium chloride, or 18-crown ether-6.

5. The method for preparing 3-(4-nitrofuran-3-oxomethyl)-3-azidomethyloxetane as described in claim 1, characterized in that, The molar ratio of the intermediate 3-azidomethyl-3-bromomethyloxetane, 3-nitro-4-hydroxyfurazan, the basic donor, and the phase transfer catalyst is 1:(1~2):(1~2):0.

02.

6. The method for preparing 3-(4-nitrofuran-3-oxomethyl)-3-azidomethyloxetane as described in claim 1, characterized in that, The polar aprotic solvent is DMF, MeCN, Acetone, or DMSO.

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