A high-yield preparation method of sodium dodecaborate

Abstract

The invention belongs to the technical field of material preparation, in particular to a high-yield preparation method of sodium dodecaborate. The invention sequentially adds NaBH4, diethylene glycol dimethyl ether and BH3·DMS into a reactor, and stirs the reactants at room temperature to fully dissolve and mix them; the high-pressure reactor is heated from room temperature to 160°C, and maintained at the temperature for 24 hours, and then naturally cooled to room temperature to obtain a reaction product; and the reaction product is filtered in a vacuum, and then washed and filtered with diethylene glycol dimethyl ether, and then vacuum dried to obtain Na2B 12 H 12 ·DGM; the dried product Na2B 12 H 12 DGM was kept at 200℃ for 12 hours under vacuum to obtain the final target product Na2B 12 H 12 The present invention proposes a new and lower-cost sodium dodecaborate (Na2B 12 H 12 ) and the target product is only Na2B 12 H 12 It is slightly soluble in diethylene glycol dimethyl ether. A high-purity product can be obtained by simple filtration operation, and the yield can reach 80%-85%.

Description

Technical Field

[0001] The invention belongs to the technical field of material preparation, and in particular relates to a high-yield preparation method of sodium dodecaborate. Background Art

[0002] Composite hydrides containing light elements (substances with relatively small molar mass) are considered to be the most promising solid-state hydrogen storage materials. Among them, metal borohydrides with high volume and mass hydrogen storage density, such as LiBH4, Mg(BH4)2 and Ca(BH4)2, have attracted widespread attention in the field of hydrogen storage. However, the main problem of this type of material in the hydrogen storage process is that BH4 - The anion is converted into the more stable dodecaborate ion (B 12 H 12 2- ), which greatly affects the reversible hydrogen absorption and desorption properties of metal borohydrides.

[0003] But on the other hand, metal dodecaborates (M x B 12 H 12 ) also has good application prospects in cancer treatment, polymer chemistry and solid-state ion conductors. x B 12 H 12 The structure of Li2B contains a closed icosahedral boron cluster with a hydrogen atom at each of the twelve corners, and has remarkable chemical and thermal stability. However, only a few metal dodecaborates, such as Li2B 12 H 12 and Na2B 12 H 12 , which can be purchased on the market at a high price (about 1,000 yuan per gram). How to synthesize such materials at low cost, high efficiency and on a large scale has become an important bottleneck restricting its development. x B 12 H 12 New synthetic methods have always been one of the important research directions in this field.

[0004] The existing B 12 H 12 2- The synthesis methods can be divided into the following two categories. The first category is through the reaction of metal borohydride (MBH4) with boranes (such as B2H6 and B 10 H 14 ) reaction method. Depending on the experimental conditions, the reaction will generate a series of boron-rich anions, such as B 12 H 12 2- 、B3H8 - , B11 H 14 - Generally speaking, higher temperatures are more conducive to the formation of BB bonds, such as Na2B 12 H 12 The synthesis of requires the reaction temperature to be raised to 180°C. However, the raw materials B2H6 and B 10 H 14 It is a flammable item, highly toxic, and expensive. The second type is a two-step synthesis method based on the oxidation of borohydride by elemental iodine, using Na2B 12 H 12 For example, the two-step synthesis reaction is as follows:

[0005] 3NaBH4+I2→NaB3H8+2NaI+2H2

[0006] 5NaB3H8→Na2B 12 H 12 +3NaBH4+8H2

[0007] Compared with the first method, this synthetic route is cheaper and easier to implement. However, due to the low conversion rate of NaBH4 and the difficulty of purification process, the final yield is not high, generally 50%-60%. Summary of the invention

[0008] In order to overcome the defects in the prior art, the present invention provides a high-yield preparation method of sodium dodecaborate. The present invention has the advantages of high yield, environmental protection, and reduced cost.

[0009] To achieve the above object, the present invention adopts the following technical solutions:

[0010] A high-yield preparation method of sodium dodecaborate, the specific steps are as follows:

[0011] S1. In a protective gas, NaBH4, diethylene glycol dimethyl ether and BH3·DMS are sequentially added into a reactor, and then the reactor is placed in a high-pressure reactor;

[0012] S2, sealing the autoclave, introducing protective gas into the autoclave, and stirring the reactants at room temperature to fully dissolve and mix them;

[0013] S3, raising the temperature of the autoclave from room temperature to 160° C. and maintaining the temperature for 24 hours, and then naturally cooling the autoclave to room temperature to obtain a reaction product;

[0014] S4, taking out the reaction product, and filtering it in vacuum, then washing and filtering the reaction product with diethylene glycol dimethyl ether, and then vacuum drying to obtain Na2B 12 H 12 Adduct, namely Na2B12 H 12 ·DGM;

[0015] S5, the dried product Na2B 12 H 12 DGM was kept at 200℃ for 12 hours under vacuum to obtain the final target product Na2B 12 H 12 .

[0016] Preferably, in step S1, NaBH4 and an electromagnetic stirring rotor are loaded into a quartz reactor and carried out in a glove box, and the glove box is filled with argon gas.

[0017] Preferably, the volume ratio of NaBH4 to BH3·DMS in step S1 is 1:5.

[0018] Preferably, in step S1, the volume of diethylene glycol dimethyl ether is L1, the volume of the reactor is L2, and 1 / 3L2<L1<2 / 3L2.

[0019] Preferably, the protective gas in step S2 is argon.

[0020] Preferably, in step S3, the temperature of the autoclave is raised from room temperature to 160° C. at a heating rate of 2° C. / min.

[0021] Preferably, in step S1, the amount of NaBH4 added is 5 mmol, the amount of diethylene glycol dimethyl ether added is 16 mL, and the amount of BH3·DMS added is 25 mmol.

[0022] Preferably, after vacuum filtering the reaction product in step S4, 10 mL of diethylene glycol dimethyl ether is used to wash and filter the reaction product three times.

[0023] Preferably, in step S4, the Na2B is obtained by vacuum drying at 80°C for 2 hours. 12 H 12 ·DGM.

[0024] Preferably, the vacuum filtration device in step S4 is a Schlenk flask with a filter element.

[0025] The advantages of the present invention are:

[0026] (1) The present invention proposes a new and lower-cost sodium dodecaborate (Na2B 12 H 12), which uses sodium borohydride (NaBH4) and borane dimethyl sulfide complex (i.e., BH3·DMS) as reaction raw materials, diethylene glycol dimethyl ether as solvent, and synthesizes sodium dodecaborate in one step in a high-pressure reactor. The selection of raw materials is more environmentally friendly and reduces costs. The use of the high-pressure reactor not only provides a closed system to limit all gaseous reactants and products, but also can increase the boiling point of diethylene glycol dimethyl ether used as a solvent, thereby increasing the solubility of the borohydride used, and among the reactants and products, only the target product Na2B 12 H 12 It is slightly soluble in diethylene glycol dimethyl ether, and a high-purity product can be obtained by simple filtration operation, and the yield can reach 80%-85%.

[0027] (2) The raw materials of the reaction of the present invention are more environmentally friendly; the prior art uses boranes, such as B2H6 and B 10 H 14 As the main boron source, such substances are flammable and highly toxic. In the present invention, relatively safe and green NaBH4 and BH3·DMS are selected to avoid the potential harm of chemical substances to the human body and the pollution to the environment; and the reaction is carried out in a closed high-pressure reactor, and the adduct of the target product can be obtained by only one step of synthesis, and then the pure Na2B can be obtained by desolvation through heat treatment. 12 H 12 , the synthesis steps are simpler.

[0028] (3) The yield and purity of the present invention are higher. Among the products of the synthesis method of the present invention, only the target product Na2B 12 H 12 It is slightly soluble in diethylene glycol dimethyl ether, so high-purity Na2B can be obtained through simple filtration operation. 12 H 12 Compared with the yield of 50%-60% in the prior art, the yield of the present invention can reach 80%-85%. The main reason is that, on the one hand, the use of a high-pressure reactor increases the boiling point of the reaction solvent diethylene glycol dimethyl ether, increases the solubility of the reaction raw material NaBH4, and improves the raw material conversion efficiency; on the other hand, the generated Na2B 12 H 12 It is slightly soluble in diethylene glycol dimethyl ether, so that the target product is retained to the maximum extent. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a diagram of the high-pressure reactor device of the present invention.

[0030] Figure 2 This is a diagram of the vacuum filtration and drying device of the present invention.

[0031] Figure 3The hydrogen coupling of the product obtained by vacuum filtration and drying (after step e) at reaction temperatures of 120°C, 160°C and 200°C of the present invention is 11 B-NMR spectrum.

[0032] Figure 4 This is the infrared spectrum of the present invention.

[0033] Figure 5 The X-ray diffraction patterns of the products under different reaction temperatures and heat treatment conditions of the present invention are shown in FIG. DETAILED DESCRIPTION

[0034] like Figure 1-5 As shown, a sodium dodecaborate (Na2B 12 H 12 ) is prepared in a high yield, the steps of which are as follows:

[0035] S1. In a protective gas, NaBH4, diethylene glycol dimethyl ether (CH3-O-C2H4-O-C2H4-O-CH3, referred to as DGM) and BH3·DMS are sequentially added to a reactor, and the reactor is then placed in a high-pressure reactor; wherein the volume ratio of NaBH4 to BH3·DMS is 1:5, and specifically, in order to make the reaction more complete, the added volume of BH3·DMS should exceed the set amount; the volume of diethylene glycol dimethyl ether is L1, the volume of the reactor is L2, and 1 / 3L2<L1<2 / 3L2

[0036] S2, sealing the autoclave, introducing protective gas into the autoclave, and stirring the reactants at room temperature to fully dissolve and mix them;

[0037] The protective gas in step S1 and step S2 is argon;

[0038] S3, heating the autoclave from room temperature to 160° C. at a heating rate of 2° C. / min, maintaining the temperature for 24 hours, and then naturally cooling to room temperature to obtain a reaction product;

[0039] S4, taking out the reaction product, and filtering it in vacuum, then washing and filtering the reaction product with diethylene glycol dimethyl ether, and then vacuum drying to obtain Na2B 12 H 12 Adduct, namely Na2B 12 H 12 ·DGM;

[0040] S5, the dried product Na2B 12 H 12 DGM was kept at 200℃ for 12 hours under vacuum to obtain the final target product Na2B 12 H 12 .

[0041] Example 1

[0042] S1. Pretreatment of reaction materials: 5.1 mmol NaBH4 and an electromagnetic stirring rotor were placed in a quartz reactor in a glove box filled with argon, and the opening of the quartz reactor was sealed with a sealing film. Filling with argon can prevent NaBH4 from direct contact with air for a long time;

[0043] S2. Reactor setup: Remove the sealing film on the quartz reactor, add 16 mL of diethylene glycol dimethyl ether and 27.7 mmol of BH3·DMS into the quartz reactor in sequence, and Figure 1 Build a high-pressure reactor experimental device;

[0044] S3, pre-reaction pretreatment: after sealing the autoclave, continuously introduce argon gas for 30 seconds to replace the air in the autoclave, and stir with an electromagnetic stirrer at room temperature for 10 minutes to fully dissolve and mix the reactants;

[0045] S4, reaction process: the temperature of the autoclave was raised from room temperature to 160°C at a rate of 2°C / min by a temperature control device, and maintained at the temperature for 24 hours, and then naturally cooled to room temperature to obtain a reaction product;

[0046] S5. Vacuum filtration and drying: Figure 2 Build a vacuum filtration and drying device; transfer all the reaction products to a Schlenk flask with a filter element for vacuum filtration, wash the filtered product three times with 10 mL of diethylene glycol dimethyl ether, and then vacuum dry it at 80 ° C for 2 hours to remove excess solvent to obtain dry Na2B 12 H 12 Adduct, namely Na2B 12 H 12 ·DGM;

[0047] S6. Heat treatment: The dried product Na2B 12 H 12 DGM was kept in vacuum at 200℃ for 12 hours to remove the residual diethylene glycol dimethyl ether in the adduct and obtain the final target product Na2B 12 H 12 one.

[0048] Example 2

[0049] S1. Pretreatment of reaction materials: 5.1 mmol NaBH4 and an electromagnetic stirring rotor were placed in a quartz reactor in a glove box filled with argon, and the opening of the quartz reactor was sealed with a sealing film. Filling with argon can prevent NaBH4 from direct contact with air for a long time;

[0050] S2. Reactor setup: Remove the sealing film on the quartz reactor, add 16 mL of diethylene glycol dimethyl ether and 27.5 mmol of BH3·DMS into the quartz reactor in sequence, and Figure 1 Build a high-pressure reactor experimental device;

[0051] S3, pre-reaction pretreatment: after sealing the autoclave, continuously introduce argon gas for 30 seconds to replace the air in the autoclave, and stir with an electromagnetic stirrer at room temperature for 10 minutes to fully dissolve and mix the reactants;

[0052] S4, reaction process: the temperature of the autoclave was raised from room temperature to 160°C at a rate of 2°C / min by a temperature control device, and maintained at the temperature for 24 hours, and then naturally cooled to room temperature to obtain a reaction product;

[0053] S5. Vacuum filtration and drying: Figure 2 Build a vacuum filtration and drying device; transfer all the reaction products to a Schlenk flask with a filter element for vacuum filtration, wash the filtered product three times with 10 mL of diethylene glycol dimethyl ether, and then vacuum dry it at 80 ° C for 2 hours to remove excess solvent to obtain dry Na2B 12 H 12 Adduct, namely Na2B 12 H 12 ·DGM;

[0054] S6. Heat treatment: The dried product Na2B 12 H 12 DGM was kept in vacuum at 200℃ for 12 hours to remove the residual diethylene glycol dimethyl ether in the adduct and obtain the final target product Na2B 12 H 12 two.

[0055] Example 3

[0056] S1. Pretreatment of reaction materials: 5.0 mmol NaBH4 and an electromagnetic stirring rotor were placed in a quartz reactor in a glove box filled with argon, and the opening of the quartz reactor was sealed with a sealing film. Filling with argon can prevent NaBH4 from direct contact with air for a long time;

[0057] S2. Reactor setup: Remove the sealing film on the quartz reactor, add 16 mL of diethylene glycol dimethyl ether and 27.6 mmol of BH3·DMS into the quartz reactor in sequence, and Figure 1 Build a high-pressure reactor experimental device;

[0058] S3, pre-reaction pretreatment: after sealing the autoclave, continuously introduce argon gas for 30 seconds to replace the air in the autoclave, and stir with an electromagnetic stirrer at room temperature for 10 minutes to fully dissolve and mix the reactants;

[0059] S4, reaction process: the temperature of the autoclave was raised from room temperature to 160°C at a rate of 2°C / min by a temperature control device, and maintained at the temperature for 24 hours, and then naturally cooled to room temperature to obtain a reaction product;

[0060] S5. Vacuum filtration and drying: Figure 2 Build a vacuum filtration and drying device; transfer all the reaction products to a Schlenk flask with a filter element for vacuum filtration, wash the filtered product three times with 10 mL of diethylene glycol dimethyl ether, and then vacuum dry it at 80 ° C for 2 hours to remove excess solvent to obtain dry Na2B 12 H 12 Adduct, namely Na2B 12 H 12 ·DGM;

[0061] S6. Heat treatment: The dried product Na2B 12 H 12 DGM was kept in vacuum at 200℃ for 12 hours to remove the residual diethylene glycol dimethyl ether in the adduct and obtain the final target product Na2B 12 H 12 three.

[0062] The experimental data of Examples 1-3 are shown in Table 1 below:

[0063] Table 1

[0064]

[0065] As shown in Table 1, the Na2B prepared in Examples 1-3 are 12 H 12 1. Na2B 12 H 12 Di and Na2B 12 H 12 The final yields of the three were 80.39%, 81.18% and 85.20% respectively.

[0066] Comparative Example 1

[0067] S1. Pretreatment of reaction materials: 5.0 mmol NaBH4 and an electromagnetic stirring rotor were placed in a quartz reactor in a glove box filled with argon, and the opening of the quartz reactor was sealed with a sealing film. Filling with argon can prevent NaBH4 from direct contact with air for a long time;

[0068] S2. Reactor setup: Remove the sealing film on the quartz reactor, add 16 mL of diethylene glycol dimethyl ether and 27.6 mmol of BH3·DMS into the quartz reactor in sequence, and Figure 1 Build a high-pressure reactor experimental device;

[0069] S3, pre-reaction pretreatment: after sealing the autoclave, continuously introduce argon gas for 30 seconds to replace the air in the autoclave, and stir with an electromagnetic stirrer at room temperature for 10 minutes to fully dissolve and mix the reactants;

[0070] S4, reaction process: using a temperature control device, the high-pressure reactor is heated from room temperature to 120°C at a rate of 2°C / min, and maintained at this temperature for 24 hours, and then naturally cooled to room temperature to obtain a reaction product;

[0071] S5. Vacuum filtration and drying: Figure 2 Build a vacuum filtration and drying device; transfer all the reaction products to a Schlenk flask with a filter element for vacuum filtration, wash the filtered product three times with 10 mL of diethylene glycol dimethyl ether, and then vacuum dry it at 80 ° C for 2 hours to remove excess solvent to obtain dry Na2B 12 H 12 Adduct, namely Na2B 12 H 12 ·DGM;

[0072] S6. Heat treatment: The dried product Na2B 12 H 12 DGM was kept in vacuum at 200℃ for 12 hours to remove the residual diethylene glycol dimethyl ether in the adduct and obtain the final target product Na2B 12 H 12 Four.

[0073] Comparative Example 2

[0074] S1. Pretreatment of reaction materials: 5.0 mmol NaBH4 and an electromagnetic stirring rotor were placed in a quartz reactor in a glove box filled with argon, and the opening of the quartz reactor was sealed with a sealing film. Filling with argon can prevent NaBH4 from direct contact with air for a long time;

[0075] S2. Reactor setup: Remove the sealing film on the quartz reactor, add 16 mL of diethylene glycol dimethyl ether and 27.6 mmol of BH3·DMS into the quartz reactor in sequence, and Figure 1 Build a high-pressure reactor experimental device;

[0076] S3, pre-reaction pretreatment: after sealing the autoclave, continuously introduce argon gas for 30 seconds to replace the air in the autoclave, and stir with an electromagnetic stirrer at room temperature for 10 minutes to fully dissolve and mix the reactants;

[0077] S4, reaction process: using a temperature control device, the high-pressure reactor is heated from room temperature to 200°C at a rate of 2°C / min, and maintained at this temperature for 24 hours, and then naturally cooled to room temperature to obtain a reaction product;

[0078] S5. Vacuum filtration and drying: Figure 2 Build a vacuum filtration and drying device; transfer all the reaction products to a Schlenk flask with a filter element for vacuum filtration, wash the filtered product three times with 10 mL of diethylene glycol dimethyl ether, and then vacuum dry it at 80 ° C for 2 hours to remove excess solvent to obtain dry Na2B 12 H 12 Adduct, namely Na2B 12 H 12 ·DGM;

[0079] S6. Heat treatment: The dried product Na2B 12 H 12 DGM was kept in vacuum at 200℃ for 12 hours to remove the residual diethylene glycol dimethyl ether in the adduct and obtain the final target product Na2B 12 H 12 five.

[0080] Comparative Example 3

[0081] S1. Pretreatment of reaction materials: 5.0 mmol NaBH4 and an electromagnetic stirring rotor were placed in a quartz reactor in a glove box filled with argon, and the opening of the quartz reactor was sealed with a sealing film. Filling with argon can prevent NaBH4 from direct contact with air for a long time;

[0082] S2. Reactor setup: Remove the sealing film on the quartz reactor, add 16 mL of diethylene glycol dimethyl ether and 27.6 mmol of BH3·DMS into the quartz reactor in sequence, and Figure 1 Build a high-pressure reactor experimental device;

[0083] S3, pre-reaction pretreatment: after sealing the autoclave, continuously introduce argon gas for 30 seconds to replace the air in the autoclave, and stir with an electromagnetic stirrer at room temperature for 10 minutes to fully dissolve and mix the reactants;

[0084] S4, reaction process: using a temperature control device, the high-pressure reactor is heated from room temperature to 120°C at a rate of 2°C / min, and maintained at this temperature for 24 hours, and then naturally cooled to room temperature to obtain a reaction product;

[0085] S5. Vacuum filtration and drying: Figure 2 Build a vacuum filtration and drying device; transfer all the reaction products to a Schlenk flask with a filter element for vacuum filtration, wash the filtered product three times with 10 mL of diethylene glycol dimethyl ether, and then vacuum dry it at 80 ° C for 2 hours to remove excess solvent to obtain the product Na2B 12 H 12 six.

[0086] Comparative Example 4

[0087] S1. Pretreatment of reaction materials: 5.0 mmol NaBH4 and an electromagnetic stirring rotor were placed in a quartz reactor in a glove box filled with argon, and the opening of the quartz reactor was sealed with a sealing film. Filling with argon can prevent NaBH4 from direct contact with air for a long time;

[0088] S2. Reactor setup: Remove the sealing film on the quartz reactor, add 16 mL of diethylene glycol dimethyl ether and 27.6 mmol of BH3·DMS into the quartz reactor in sequence, and Figure 1 Build a high-pressure reactor experimental device;

[0089] S3, pre-reaction pretreatment: after sealing the autoclave, continuously introduce argon gas for 30 seconds to replace the air in the autoclave, and stir with an electromagnetic stirrer at room temperature for 10 minutes to fully dissolve and mix the reactants;

[0090] S4, reaction process: using a temperature control device, the high-pressure reactor is heated from room temperature to 200°C at a rate of 2°C / min, and maintained at this temperature for 24 hours, and then naturally cooled to room temperature to obtain a reaction product;

[0091] S5. Vacuum filtration and drying: Figure 2 Build a vacuum filtration and drying device; transfer all the reaction products to a Schlenk flask with a filter element for vacuum filtration, wash the filtered product three times with 10 mL of diethylene glycol dimethyl ether, and then vacuum dry it at 80 ° C for 2 hours to remove excess solvent to obtain the product Na2B 12 H 12 seven.

[0092] Comparative Example 5

[0093] Na2B purchased from the market 12 H 12 , denoted as Na2B 12 H12 eight.

[0094] The Na2B prepared in Example 3 was sequentially 12 H 12 The products obtained in Examples 1-5 are 11 B NMR spectroscopy ( 11 B-NMR), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD) were used to confirm the purity and structure of the product. Figure 3-4 shown.

[0095] according to Figure 3 It can be seen that at the reaction temperatures of 120°C and 160°C, only the target product was detected in the products obtained in Example 3 and Comparative Example 1, and no other boron-containing compounds were detected; when the reaction temperature reached 200°C, in the product obtained in Comparative Example 2, in addition to the target product, a by-product [B 11 H 11 ] 2- ; In addition, there is no characteristic peak at a reaction temperature of 90°C; Figure 3 The results show that the reaction temperature should be controlled between 120-160°C, otherwise pure Na2B cannot be obtained. 12 H 12 ·DGM.

[0096] Depend on Figure 4 It can be seen that B 12 H 12 2- The infrared characteristic peak of the ion is at 1074 cm -1 、2476cm -1 、713cm -1 and 539cm -1 The samples without heat treatment (i.e. the products obtained in Comparative Examples 3-4) have a peak at 3000-2750 cm -1 and 1500-1300cm -1 In the wave number range, the CH bond and CO bond of diethylene glycol dimethyl ether are reflected. It can be seen that the product of Example 3 after heat treatment at 200° C. has completely removed the added diethylene glycol dimethyl ether.

[0097] Figure 5 The X-ray diffraction patterns of the products under different reaction temperatures and heat treatment conditions are shown in Table 1. The X-ray diffraction patterns of the samples after the reaction temperature of 120°C (Example 1), 160°C (Comparative Example 1) and 200°C (Comparative Example 2) are similar to those of the purchased Na2B 12 H 12 The spectrum is highly consistent with the crystallographic database Na2B 12 H 12The low temperature phase structure of (ICSD 164649) proves that the reaction product under this condition is pure Na2B 12 H 12 The sample without heat treatment (i.e. the product obtained in Comparative Example 3-4) showed the same 12 H 12 The structures are completely different, and the products at reaction temperatures of 120°C and 160°C are also different, although both can obtain pure Na2B after heat treatment. 12 H 12 However, the product yield corresponding to the reaction temperature of 160℃ is significantly higher than that of 120℃.

[0098] And through the regulation of reaction conditions and the characterization of reaction products, it is deduced that the synthesis method follows the following chemical reaction formula:

[0099] 2NaBH4+10(CH3)2S·BH3→Na2B 12 H 12 +10(CH3)2S+13H2

[0100] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A high-yield preparation method of sodium dodecaborate, characterized in that: The specific steps are as follows: S1. In a protective gas, NaBH4, diethylene glycol dimethyl ether and BH3·DMS are sequentially added into a reactor, and then the reactor is placed in a high-pressure reactor; S2, sealing the autoclave, introducing protective gas into the autoclave, and stirring the reactants at room temperature to fully dissolve and mix them; S3, raising the temperature of the autoclave from room temperature to 160° C. and maintaining the temperature for 24 hours, and then naturally cooling the autoclave to room temperature to obtain a reaction product; S4, taking out the reaction product, and filtering it in vacuum, then washing and filtering the reaction product with diethylene glycol dimethyl ether, and then drying it in vacuum to obtain Na2 B 12 H 12 adduct, namely Na2 B 12 H 12 ·DGM; S5, the dried product Na2 B 12 H 12 DGM was kept at 200℃ for 12 hours under vacuum to obtain the final target product Na2 B 12 H 12 ; Step S3: heating the autoclave from room temperature to 160°C at a rate of 2°C / min; In step S1, the amount of NaBH4 added is 5 mmol, the amount of diethylene glycol dimethyl ether added is 16 mL, and the amount of BH3·DMS added is 25 mmol; In step S4, the reaction product is vacuum filtered and then washed and filtered three times using 10 mL of diethylene glycol dimethyl ether.

2. A high-yield preparation method of sodium dodecaborate according to claim 1, characterized in that: In step S1, NaBH4 and an electromagnetic stirring rotor are loaded into a quartz reactor and carried out in a glove box filled with argon.

3. A high-yield preparation method of sodium dodecaborate according to claim 1, characterized in that: The volume ratio of NaBH4 to BH3·DMS in step S1 is 1:

5.

4. A high-yield preparation method of sodium dodecaborate according to claim 1, characterized in that: In step S1, the volume of diethylene glycol dimethyl ether is L1, the volume of the reactor is L2, and 1 / 3L2<L1<2 / 3L2.

5. A high-yield preparation method of sodium dodecaborate according to claim 1, characterized in that: The protective gas in step S2 is argon.

6. A high-yield preparation method of sodium dodecaborate according to claim 1, characterized in that: In step S4, Na2 B is obtained by vacuum drying at 80°C for 2 hours. 12 H 12 ·DGM.

7. A high-yield preparation method of sodium dodecaborate according to claim 1, characterized in that: The vacuum filtration device in step S4 is a Schlenk flask with a filter element.

Images