Method for measuring solution concentration in crystallization process of 3, 4-dinitrofurazanyl furoxan

Abstract

The invention discloses a method for determining the solution concentration in the crystallization process of 3, 4-dinitrofurazan furoxan oxide, and relates to the technical field of energetic crystal materials. According to the method, an EasySampler and HPLC (High Performance Liquid Chromatography) combined method is utilized, the solubility of DNTF is measured, a standard curve of DNTF solution concentration and peak area is established by utilizing a high performance liquid chromatograph, then the EasySampler is utilized to sample a crystallization process and perform HPLC analysis, and then the solution concentration at each moment is calculated by utilizing an equation of the standard curve. According to the method, EasySampler equal interval sampling is combined with off-line HPLC (High Performance Liquid Chromatography) analysis, and a curve that the concentration of the main component of the solution changes along with the temperature is constructed. In the dominant period of crystal growth, the concentration change rate and the solid-liquid interface area are in an approximately linear relationship. The experimental data provides a necessary demonstration basis for subsequent improvement of a non-ideal system crystallization kinetics theory.

Description

Technical Field

[0001] The invention relates to the technical field of energetic crystal materials, in particular to a method for determining the concentration of a solution during the crystallization process of 3,4-dinitrofurazanyl furazan oxide. Background Art

[0002] 3,4-Dinitrofurazanyl furazan oxide (DNTF) is an important new type of high-energy explosive with high power, moderate sensitivity, and good thermal stability. It has good application prospects in the field of energetic materials. Since its domestic synthesis in 2002, it has attracted great attention due to its high energy characteristics. The structural formula of DNTF is shown in the figure below:

[0003] DNTF has high density, high detonation velocity (higher than HMX), and high detonation heat. Its overall performance is superior to that of HMX and close to that of CL-20. "Research on the Properties and Applications of 3,4-Furazanyl Furazan Oxide, a High Energy Density Material" (Acta Armamentarii, Issue 2, 2004, pp. 155-158) reported on DNTF elemental explosives. The paper used DNTF recrystallization in an acetic acid / water system. The resulting crystals exhibited high acidity, large particle size, high impact sensitivity (96%), and a relative density of 95%. Patent ZL201510100531.2 "A method for recrystallizing high-quality single-element explosives" discloses a method for preparing a mixed explosive with high-quality DNTF as the main explosive, which has high molding density and low mechanical sensitivity, wherein the high-quality DNTF is prepared by a solvent-non-solvent method; Patent ZL201811031142.9 "A low shock wave sensitivity DNTF and its preparation method" discloses a method for preparing low shock wave sensitivity DNTF by mixing calcium stearate and sodium dodecyl sulfate, substances with low impact sensitivity; Patent CN202310327853.5 "A method for preparing spherical crystals of 3,4-dinitrofurazanyl furazan oxide" discloses a preparation technology for spherical DNTF crystals by adding additives during the cooling crystallization process.

[0004] However, due to the limitations of current theoretical models, we are unable to provide a complete kinetic description of the crystallization process. Classical nucleation theory has significant deviations in explaining the primary nucleation stage under non-equilibrium conditions, especially for systems with strong anisotropy of intermolecular forces. The existing equations fail to fully consider the coupling effects of local concentration fluctuations and interfacial tension. Molecular dynamics simulations are limited by the computational scale and are difficult to capture the mesoscopic evolution processes above the microsecond level in actual industrial crystallization, while the continuum assumption oversimplifies the quantum chemical details of the lattice-solvent interaction. This theoretical gap makes it impossible for us to accurately predict the critical nucleus size through first principles, nor to establish a reliable morphological evolution equation to verify the observed dendrite fractal growth behavior. Summary of the Invention

[0005] The purpose of this invention is to accurately measure the concentration of a DNTF solution during crystallization. Combining this with solubility data, the supersaturation and supersaturation ratio can then be calculated to guide the crystallization process. To this end, the present invention provides an accurate and efficient method for measuring the concentration of 3,4-dinitrofurazanylfurazan oxide during crystallization. The core of this method is the use of an EasySampler coupled with a high-performance liquid chromatograph (HPLC) to accurately measure the concentration of the DNTF solution at each moment during crystallization, thereby guiding the crystallization process.

[0006] The present invention is achieved through the following technical solutions: A method for determining the concentration of a solution during the crystallization process of 3,4-dinitrofurazanyl furazan oxide comprises the following steps: 1) Determine the solubility of DNTF at different temperatures in the crystallization system.

[0007] 2) Establish a standard curve of DNTF concentration and peak area.

[0008] 3) During the crystallization process, samples were taken at equal intervals for liquid phase analysis.

[0009] 4) Based on the standard curve, calculate the concentration of DNTF solution at each time during the crystallization process.

[0010] Furthermore, in step 2), a standard curve of DNTF concentration and peak area was established using high performance liquid chromatography (HPLC).

[0011] Furthermore, a standard curve of DNTF concentration and peak area was established by high performance liquid chromatography (HPLC), and the correlation R 2 Greater than 0.995.

[0012] Furthermore, in step 3), EasySampler is used to take samples at equal intervals for liquid phase analysis. EasySampler is a fully automated sampling process, including quenching, dilution, and transfer to sample vials. This eliminates manual liquid handling, reduces risks, and improves operator safety. EasySampler collects fixed-volume samples, preventing any changes in sample specifications. After quenching, the liquid handling system dilutes the sample to a user-specified concentration and transfers it to a sample vial for offline testing. This reduces sample preparation time and eliminates human error.

[0013] Furthermore, the sampling volume of EasySampler was 20 μL. The small sampling volume reduced the impact of sampling on the crystallization system. The sample was analyzed by HPLC, which accurately reflected the solution concentration.

[0014] Furthermore, in step 4), the concentration of the DNTF solution at each time during the crystallization process is calculated based on the standard curve, and then combined with the solubility data to calculate the supersaturation and supersaturation ratio.

[0015] In summary, the present method provides an accurate and efficient method for determining the solution concentration of DNTF during crystallization, utilizing the EasySampler coupled with HPLC. Specifically, the method utilizes EasySampler coupled with HPLC (high-performance liquid chromatography) to determine DNTF solubility, establish a standard curve of DNTF solution concentration versus peak area using HPLC, then sample the crystallization process using EasySampler and analyze it with HPLC. The solution concentration at each time point is then calculated using the equation of the standard curve.

[0016] The present invention indirectly tracks the crystallization process by monitoring changes in solution concentration in real time. The experimental observation data can provide key kinetic information. Using EasySampler sampling at equal intervals combined with offline HPLC analysis, the present invention constructs a curve showing the concentration variation of the main components of the solution as a function of temperature. During the dominant phase of crystal growth, the rate of concentration change shows an approximately linear relationship with the solid-liquid interface area. These experimental data provide the necessary empirical basis for the subsequent refinement of the crystallization kinetics theory for non-ideal systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The drawings herein are used to provide further illustration of the present invention and constitute a part of this application. The illustrative embodiments of the present invention and their description are used to explain the present invention and do not constitute improper limitations on the present invention.

[0018] Figure 1 The standard curve of DNTF concentration and peak area in step 2) of Example 1 Figure 2 4) of Example 1 at each moment in step 4) of the sample concentration and solubility curve. DETAILED DESCRIPTION

[0019] In order to enable those skilled in the art to better understand the present invention, the following is a further clear and complete description of the technical solution of the present invention in conjunction with the accompanying drawings and specific embodiments. It should be noted that, unless there is a conflict, the features in the embodiments and examples of this application can be combined with each other.

[0020] The technical solution of the present invention is to provide a method for determining the solution concentration during the crystallization process of 3,4-dinitrofurazanyl furazan oxide, comprising the following steps: 1) Determine the solubility of DNTF at different temperatures in the crystallization system.

[0021] 2) Use high performance liquid chromatography to establish a standard curve of DNTF concentration and peak area, and the correlation R 2 Greater than 0.995.

[0022] 3) During the crystallization process, EasySampler was used to take samples at equal intervals for liquid phase analysis. To minimize the impact of sampling on the crystallization system, the EasySampler sampling volume was 20 μL.

[0023] 4) Based on the standard curve, calculate the concentration of DNTF solution at each time during the crystallization process.

[0024] 5) Based on the calculated DNTF solution concentration at each moment during the crystallization process and combined with the solubility data, the supersaturation and supersaturation ratio are calculated.

[0025] The technical solution of the present invention is further described below through a specific embodiment: Example 1

[0026] This embodiment provides a method for determining the solution concentration during the crystallization process of 3,4-dinitrofurazanyl furazan oxide, comprising the following steps: 1) Determination of the solubility of DNTF in ethanol system: The solubility of DNTF in ethanol system in the range of 20~65℃ was determined by laser dynamic method.

[0027] 2) Use high performance liquid chromatography to establish a standard curve of DNTF concentration and peak area: Using a volumetric flask and analytical balance, a standard solution of DNTF in ethanol system was prepared at a concentration of 0.2-2.0 mg / mL with a gradient of 0.2. The prepared samples were analyzed by high performance liquid chromatography to establish a standard curve of DNTF concentration and peak area in ethanol system. The results are shown in Table 1. Figure 1 The equation of the standard curve is: y = 2502.3 x + 417.43, R² = 0.9975.

[0028] Table 1 Correspondence between DNTF concentration and peak area Serial number Concentration / (mg / ml) Peak area / mV 1 0.4 1524.33 2 0.6 1940.18 3 0.8 2335.07 4 1 2854.69 5 1.2 3338.99 6 1.4 3923.01 7 1.6 4455.25 8 1.8 5005.00 9 2 5405.55 3) Add 23.59 g of DNTF and 100 mL of anhydrous ethanol to the crystallization kettle with stirring at 300 r / min. Cool the temperature to 60°C at a rate of 0.1°C / min. Add 0.18 g of seed crystals, grow the crystals for 30 minutes, and continue cooling the temperature to room temperature at a rate of 0.1°C / min. During the crystallization process, samples were taken at regular intervals using an EasySampler with a gradient of 1°C. The samples were analyzed for liquid phase analysis. The results are shown in Table 2. Table 2 Sample peak area Sampling number Sampling temperature / ℃ Peak area / mV 3-1 60 6046.01 3-2 59 6021.79 3-3 57 5721.04 3-4 55 5400.82 3-5 53 5107.62 3-6 51 4715.62 3-7 49 4510.77 3-8 47 4255.79 3-9 45 3955.93 3-10 43 3752.85 3-11 41 3521.18 3-12 39 3334.61 3-13 37 3215 3-14 35 3006.26 3-15 33 2859.32 3-16 31 2752.69 3-17 29 2558.52 3-18 27 2398.93 3-19 25 2214.12 3-20 23 2034.00 3-21 21 1861.85 4) According to the standard curve, the concentration of DNTF solution at each time during the crystallization process was calculated. The results are shown in Table 3. Figure 2 shown.

[0029] Table 3 Correspondence between sample peak area and concentration Sampling number Sampling temperature / ℃ Peak area / mV Sample concentration / (g / 100ml) 3-1 60 6046.01 22.4936 3-2 59 6021.79 22.3968 3-3 57 5721.04 21.1949 3-4 55 5400.82 19.9152 3-5 53 5107.62 18.7435 3-6 51 4715.62 17.1770 3-7 49 4510.77 16.3583 3-8 47 4255.79 15.3393 3-9 45 3955.93 14.1410 3-10 43 3752.85 13.3294 3-11 41 3521.18 12.4036 3-12 39 3334.61 11.6580 3-13 37 3215 11.1800 3-14 35 3006.26 10.3458 3-15 33 2859.32 9.7586 3-16 31 2752.69 9.3325 3-17 29 2558.52 8.5565 3-18 27 2398.93 7.9187 3-19 25 2214.12 7.1802 3-20 23 2034.00 6.4603 3-21 21 1861.85 5.7724 5) Further calculations are performed to obtain supersaturation, supersaturation ratio, and suspension density, and then crystallization kinetics-related parameters are obtained to guide the crystallization process.

[0030] The above embodiment merely represents one embodiment of the present invention. While the description is relatively specific and detailed, it should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art may make various modifications and improvements without departing from the scope of the present invention, and such modifications and improvements are all within the scope of protection of the present invention.

Claims

1. A method for determining the solution concentration during the crystallization of 3,4-dinitrofurazanyl furazan oxide, characterized in that: The steps include: 1) Determine the solubility of DNTF at different temperatures in the crystallization system; 2) Establish a standard curve of DNTF concentration and peak area; 3) During the crystallization process, samples were taken at equal intervals for liquid phase analysis; 4) Based on the standard curve, calculate the concentration of DNTF solution at each time during the crystallization process.

2. the assay method of solution concentration in the 3,4-dinitrofurazanyl furazan oxide crystallization process according to claim 1, is characterized in that: In step 2), a standard curve of DNTF concentration and peak area was established using high performance liquid chromatography.

3. The method for determining the solution concentration in the 3,4-dinitrofurazanyl furazan oxide crystallization process according to claim 2, wherein: Correlation R 2 Greater than 0.

995.

4. The method for determining the concentration of the solution in the 3,4-dinitrofurazanyl oxide furazan crystallization process according to claim 1, wherein: In step 3), EasySampler was used to take samples at equal intervals.

5. The method for determining the solution concentration in the 3,4-dinitrofurazanyl furazan oxide crystallization process according to claim 4, wherein: The sample volume using EasySampler was 20 μL.

6. The method for determining the solution concentration in the 3,4-dinitrofurazanyl oxide furazan crystallization process according to claim 1, wherein: In step 4), the concentration of the DNTF solution at each time during the crystallization process is calculated based on the standard curve, and then combined with the solubility data to calculate the supersaturation and supersaturation ratio.

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