A method for preparing cyano borohydride pyridine metal complexes

Abstract

The application relates to a method for preparing a cyano borohydride pyridine metal complex, and the specific steps are as follows: a certain amount of transition metal salt is weighed and added into a container, a solvent is added, stirring is uniformly carried out, a pyridine ligand is added into the container, reaction is carried out at 20-80 DEG C for 0.5-6h, sodium cyano borohydride is added into the container, backflow is carried out at 20-80 DEG C for 2-6h, cooling is carried out, continuous stirring is carried out for 2-12h, filtering is carried out, the precipitated product is washed and dried, and the cyano borohydride pyridine metal complex is obtained. The metal complex is self-ignited when being contacted with a strong oxidant, has good ignition and combustion characteristics, and can be applied to the combustion field of solid fuel or solid propellant. The preparation method is simple and the conditions are mild.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of self-ignition propellant technology and energetic materials, and particularly relates to a method for preparing a cyano borohydride pyridine metal complex. BACKGROUND

[0002] Propellant is the main power source of rockets, directly determines the propelling performance and carrying capacity of rockets, and provides a strong guarantee for modern space industry and deep space exploration. Solid propellant is a kind of energy material capable of stable combustion and releasing a large amount of high-temperature gas, and its characteristics of easy storage and transportation make it widely used in satellites, space vehicles and rockets, and has great significance for the development of aviation industry.

[0003] In the complex, the complex with self-ignition performance formed by combining organic energetic ligand, self-ignition anion and metal ion is called self-ignition complex, which has the advantages of organic energetic ligand, metal ion and complex, and has a wider application range. Metal ion has a catalytic effect in the combustion reaction, and the introduction of nitrogen-rich ligand can improve the energy level of the complex. By adjusting the central metal ion and organic ligand, the self-ignition performance of the self-ignition complex can be further controlled, so that a new type of self-ignition complex meeting the performance requirements of solid propellant can be designed.

[0004] Therefore, developing self-ignition complexes with ultra-short ignition delay time, high specific impulse and high density has become a hot spot in the field of propellants. The cyano borohydride pyridine metal complexes designed accordingly all exhibit good catalytic combustion performance and short ignition delay time. The ultra-fast self-ignition and suitable physical and chemical properties of these complexes make them have the potential to become self-ignition propellant fuels, and have application prospects in solid propellants. SUMMARY

[0005] The purpose of the present application is to provide a method for preparing a cyano borohydride pyridine metal complex, which self-ignites when contacted with a strong oxidizing agent such as dinitrogen tetroxide, fuming nitric acid and hydrogen peroxide, has a short ignition delay time, good combustion and catalytic effect, can be used as a fuel or a burning rate adjusting component of a solid propellant, improves the performance of the propellant, and the preparation method is simple, the conditions are mild, and the yield is high.

[0006] The technical scheme of the present application is: a method for preparing a cyano borohydride pyridine metal complex, the specific steps of which are: weighing a certain amount of transition metal salt into a container, adding a solvent, stirring uniformly, adding a pyridine ligand into the container, reacting at 20-80℃ for 0.5-6h, then adding sodium cyano borohydride into the container, refluxing at 20-80℃ for 2-6h, cooling, continuously stirring for 2-12h, filtering, washing the precipitated product, and drying to obtain the cyano borohydride pyridine metal complex. The general structure thereof is:

[0007]

[0008] In the formula, M is a transition metal, preferably M is Cu, Mn, Zn, Ni, Cr or Co; R is any one of straight-chain alkane or alkene containing 1-4 carbon atoms, or R is any one of amino, pyridine and cyano, preferably R is methyl, ethyl, propyl, vinyl, amino, pyridine or cyano; m represents the number of pyridine ligands, generally 2, 4, 6; n represents the number of cyanoborohydride, generally 2, 4.

[0009] Preferably, the above-mentioned transition metal salt is a hydrochloride, nitrate or acetate salt corresponding to the transition metal M; wherein M is Cu, Mn, Zn, Ni, Cr or Co.

[0010] Preferably, the above-mentioned pyridine ligand is pyridine, bipyridine, 4-methylpyridine, 4-ethylpyridine, 4-vinylpyridine, 4-propylpyridine, 4-aminopyridine or 4-cyanopyridine.

[0011] Preferably, the molar ratio of the above-mentioned transition metal salt and pyridine ligand is 1:(2-4); the molar ratio of the above-mentioned transition metal salt and sodium cyanoborohydride is 1:(1-2).

[0012] Preferably, the solvent is methanol, ethanol, acetonitrile or water.

[0013] Advantages:

[0014] (1) The synthesis method of the cyanoborohydride pyridine metal complex provided by the present application has the advantages of simple process, high yield, mild conditions and low cost, and is conducive to large-scale production.

[0015] (2) The cyanoborohydride anion in the cyanoborohydride pyridine metal complex provided by the present application has strong reducing property and immediately self-ignites when in contact with a strong oxidizing agent, and has good self-ignition performance. The metal ion has good catalytic effect on combustion. The cyanoborohydride pyridine metal complex provided by the present application has short ignition delay time and has the potential to become a solid propellant fuel or a burning rate regulator.

[0016] (3) The substituted pyridine ligand in the cyanoborohydride pyridine metal complex provided by the present application releases a large amount of heat during combustion, and the presence of the side chain of the substituent improves the ignition characteristics of the complex. The metal complex with directional self-ignition characteristics can be designed by simply adjusting the side chain of the ligand. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 Molecular structure unit diagram of cyanoborohydride pyridine copper prepared in Example 1.

[0018] Figure 2 The ignition test results of the cyanoborohydride pyridine copper prepared in Example 1 and fuming nitric acid are shown in the figure.

[0019] Figure 3 The molecular structure unit diagram of the cyanoborohydride dipyridine nickel prepared in Example 2.

[0020] Figure 4 The ignition test results of the cyanoborohydride dipyridine nickel prepared in Example 2 and fuming nitric acid are shown in the figure.

[0021] Figure 5 The ignition test results of the cyanoborohydride dipyridine copper prepared in Example 3 and fuming nitric acid are shown in the figure. DETAILED DESCRIPTION

[0022] The following examples are used to describe the present application in more detail. These examples are only a description of the best mode of the present application and do not have any limitation on the protection scope of the present application.

[0023] In the following examples:

[0024] The self-ignition delay time test of the product prepared in the examples and fuming nitric acid is carried out by the following method: 15 mg of the final product described in any of the examples is placed in a glass vial, a plastic straw is used to suck fuming nitric acid, and a drop of fuming nitric acid (about 40 μL) is added 5 cm above the glass vial. Before adding the fuming nitric acid, start recording the ignition process of the target sample at a speed of 1000 frames per second with a high-speed camera, and set the contact time of fuming nitric acid and sample to 0 ms.

[0025] Preparation of cyanoborohydride pyridine copper in Example 1

[0026] 0.242 g (1 mmol) of copper nitrate trihydrate is added to 20 mL of methanol, and after being fully dissolved by stirring at 80°C, 0.158 g (2 mmol) of pyridine is added to the solution, and the reaction is carried out for 2 h. Then, 0.126 g (2 mmol) of sodium cyanoborohydride is added to the solution, and the reflux reaction is continued for 2 h. After cooling to room temperature, the solution is stirred for 2 h, and then filtered and washed with methanol or ethanol for two to three times. The solid precipitate is dried at 60°C for 24 h to obtain a solid powder product. The filtrate is slowly evaporated at room temperature to obtain a single crystal of the complex.

[0027] The structure of the complex is determined by an X-ray single crystal diffractometer, as shown in Table 1. Figure 1 According to the test structure, the complex is crystallized in a monoclinic crystal system P21 / n space group. There is one Cu(II) ion, one pyridine molecule and one CBH anion in the asymmetric unit. Each Cu(II) ion is coordinated with two pyridine molecules and two CBH anions. The crystal calculation density is 1.289 g·cm -3, the molecular formula is C 12 H 16 B2N4Cu, the lattice parameters are a = 9. 01 A, b = 9. 01 A, c = 17. 01 A, α = 90. 00°, β = 90. 00°, γ = 90. 00° The bond length range of Cu-N is 1. 99-2. 01 A. The bond angle range of N-Cu-N is 89. 84-180. 0°. The central Cu 2+ is coordinated with 4 nitrogen atoms, of which 2 nitrogen atoms are provided by 2 pyridine rings, and the other 2 nitrogen atoms are from the CBH anion end.

[0028] The complex prepared in this example is tested as follows:

[0029] The complex is tested for self-ignition delay time with fuming nitric acid, and the test results are shown in Table 1. Figure 2 The ignition delay time of cyanoborohydride copper with fuming nitric acid is 3 ms, which is shorter, and has good self-ignition performance.

[0030] Preparation of cyanoborohydride nickel dipyridine of Example 2

[0031] 0.238 g (1 mmol) of nickel chloride hexahydrate is added to 20 mL of ethanol, and after being fully dissolved by stirring at 40°C, 0.312 g (2 mmol) of dipyridine is added to the solution, and the reaction is carried out for 2 h, after which 0.126 g (2 mmol) of sodium cyanoborohydride is added to the solution, and the reflux reaction is continued for 4 h, and after being cooled to room temperature, the stirring is carried out for 10 h, and the solid precipitate is filtered and washed with methanol or ethanol for two to three times, and dried at 60°C for 24 h to obtain a solid powder product. The filtrate is slowly evaporated at room temperature to obtain a single crystal of the complex.

[0032] The structure of the complex is determined by an X-ray single crystal diffractometer, as shown in Table 2. Figure 3 According to the test structure, the complex crystal belongs to a monoclinic system, the space group is P21 / c, the molecular formula is C 22 H 22 B2N6Ni, the lattice parameters are a = 9. 01 A, b = 9. 01 A, c = 17. 01 A, α = 90. 00°, β = 90. 00°, γ = 90. 00° The bond length range of Ni-N is 1. 99-2. 01 A. The bond angle range of N-Ni-N is 78. 34-176. 82°. The crystal density is 1. 306 g·cm -3 , and there is one Ni 2+ , two dipyridine ligands and two CBH anions in the asymmetric unit. The central Ni 2+ is coordinated with 6 nitrogen atoms, of which 4 nitrogen atoms are provided by 2 dipyridine rings, and the other 2 nitrogen atoms are from the CBH anion end, forming a hexacoordinate octahedral structure.

[0033] The complex prepared in this example is tested as follows:

[0034] The complex was tested for self-ignition delay time with fuming nitric acid, and the test results are shown in Table 1. The self-ignition delay time of cyanoborohydride dipyridyl nickel with fuming nitric acid was 15 ms, and the self-ignition delay time was short, and the self-ignition performance was good. Figure 4 The complex was tested for self-ignition delay time with fuming nitric acid, and the test results are shown in Table 1. The self-ignition delay time of cyanoborohydride dipyridyl nickel with fuming nitric acid was 15 ms, and the self-ignition delay time was short, and the self-ignition performance was good.

[0035] Example 3 Preparation of cyanoborohydride copper dipyridyl

[0036] 0.134 g (1 mmol) of anhydrous copper chloride was added to 20 mL of acetonitrile, and after stirring to dissolve completely at 20°C, 0.312 g (2 mmol) of dipyridyl was added to the solution, and reacted for 3 h, then 0.126 g (2 mmol) of sodium cyanoborohydride was added to the solution, and the reaction was continued for 4 h under reflux, and after standing to room temperature, the reaction was continued for 12 h, and the solid precipitate was filtered and collected, washed with acetonitrile or ethanol for two to three times, and dried at 60°C for 24 h to obtain a solid powder product.

[0037] The molecular structure unit of the complex prepared in this example contains 1 Cu 2+ , two dipyridyl ligands, and two cyanoborohydride ions.

[0038] The complex prepared in this example was tested as follows:

[0039] The complex was tested for self-ignition delay time with fuming nitric acid, and the test results are shown in Table 1. The self-ignition delay time of cyanoborohydride dipyridyl nickel with fuming nitric acid was 15 ms, and the self-ignition delay time was short, and the self-ignition performance was good. Figure 5 The complex was tested for self-ignition delay time with fuming nitric acid, and the test results are shown in Table 1. The self-ignition delay time of cyanoborohydride dipyridyl nickel with fuming nitric acid was 15 ms, and the self-ignition delay time was short, and the self-ignition performance was good.

[0040] Example 4 Preparation of cyanoborohydride manganese vinylpyridine

[0041] 0.126 g (1 mmol) of anhydrous manganese chloride was added to 20 mL of ethanol, and after stirring to dissolve completely at 80°C, 0.420 g (4 mmol) of 4-vinylpyridine was added to the solution, and reacted for 6 h, then 0.126 g (2 mmol) of sodium cyanoborohydride was added to the solution, and the reaction was continued for 6 h under reflux, and after cooling to room temperature, the reaction was continued for 8 h with stirring, and the solid precipitate was filtered and collected, washed with ethanol for two to three times, and dried at 60°C for 24 h to obtain a solid powder product.

[0042] The molecular structure unit of the complex prepared in this example contains 1 Mn 2+ , four 4-vinylpyridine ligands, and two cyanoborohydride ions.

[0043] The complex prepared in this example was tested as follows:

[0044] The complex is tested for self-ignition delay time with fuming nitric acid, and the ignition delay time of cyanoborohydride methylpyridine zinc with fuming nitric acid is 27 ms, which is relatively short, and has good self-ignition performance.

[0045] Example 5 Preparation of cyanoborohydride aminopyridine cobalt

[0046] 0.129 g (1 mmol) of anhydrous cobalt chloride is added to 20 mL of ethanol, after being fully dissolved by stirring at 60°C, 0.188 g (2 mmol) of 4-aminopyridine is added to the solution, and the reaction is carried out for 0.5 h, then 0.063 g (1 mmol) of sodium cyanoborohydride is added to the solution, and the reaction is continued under reflux for 2 h, after cooling to room temperature and stirring for 12 h, the solid precipitate is filtered and collected, washed with ethanol for two to three times, and dried at 60°C for 24 h to obtain a solid powder product.

[0047] The molecular structure unit of the complex prepared in this example contains one Co 2+ , two 4-aminopyridine ligands, and one cyanoborohydride ion.

[0048] The complex prepared in this example is tested as follows:

[0049] The complex is tested for self-ignition delay time with fuming nitric acid, and the ignition delay time of cyanoborohydride methylpyridine zinc with fuming nitric acid is 27 ms, which is relatively short, and has good self-ignition performance.

[0050] Example 6 Preparation of cyanoborohydride methylpyridine zinc

[0051] 0.189 g (1 mmol) of zinc nitrate is added to 20 mL of water, after being fully dissolved by stirring at 60°C, 0.372 g (4 mmol) of 4-methylpyridine is added to the solution, and the reaction is carried out for 2 h, then 0.126 g (2 mmol) of sodium cyanoborohydride is added to the solution, and the reaction is continued under reflux for 2 h, after cooling to room temperature and stirring for 8 h, the solid precipitate is filtered and collected, washed with water or ethanol for two to three times, and dried at 60°C for 24 h to obtain a solid powder product.

[0052] The molecular structure unit of the complex prepared in this example contains one Zn 2+ , four 4-methylpyridine ligands, and two cyanoborohydride ions.

[0053] The complex prepared in this example is tested as follows:

[0054] The complex is tested for self-ignition delay time with fuming nitric acid, and the ignition delay time of cyanoborohydride methylpyridine zinc with fuming nitric acid is 27 ms, which is relatively short, and has good self-ignition performance.

[0055] Example 7 Preparation of cyanoborohydride ethylpyridine copper

[0056] 0.242 g (1 mmol) of copper nitrate trihydrate was added to 20 mL of ethanol, after stirring to dissolve completely at 60 °C, 0.428 g (4 mmol) of 4-ethylpyridine was added to the solution, the reaction was carried out for 2 h, then 0.126 g (2 mmol) of sodium cyanoborohydride was added to the solution, the reaction was carried out for 2 h under reflux, after cooling to room temperature, stirring was carried out for 8 h, the solid precipitate was filtered and collected, washed with ethanol for 2-3 times, dried at 60 °C for 24 h to obtain a solid powder product.

[0057] The molecular structure unit of the complex prepared in this example contains 1 Cu 2+ , four 4-ethylpyridine ligands, and two cyanoborohydride ion.

[0058] The complex prepared in this example was tested as follows:

[0059] The complex was tested for self-ignition delay time with fuming nitric acid, the ignition delay time of cyanoborohydride ethylpyridine copper with fuming nitric acid was 19 ms, the ignition delay time was short, and the self-ignition performance was good.

Claims

1. A method for preparing a cyano borohydride pyridine metal complex, comprising the following steps: weighing a certain amount of a transition metal salt into a container, adding a solvent, stirring until uniform, adding a pyridine ligand into the container, reacting at 20-80 ℃ for 0.5-6 h, adding sodium cyano borohydride into the container, refluxing at 20-80 ℃ for 2-6 h, cooling, continuously stirring for 2-12 h, filtering, washing the precipitated product, drying, and obtaining the cyano borohydride pyridine metal complex; wherein the transition metal salt is a hydrochloride, nitrate or acetate of a transition metal M; M is Cu, Mn, Zn, Ni or Co; the pyridine ligand is pyridine, bipyridine, 4-methylpyridine, 4-ethylpyridine, 4-vinylpyridine, 4-propylpyridine, 4-aminopyridine or 4-cyanopyridine.

2. The method of claim 1, wherein The molar ratio of the transition metal salt to the pyridine ligand is 1: (2-4) ; the molar ratio of the transition metal salt to sodium cyano borohydride is 1: (1-2).

3. The method of claim 1, wherein The solvent is methanol, ethanol, acetonitrile or water.

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