Synthesis method of borane compound NH3B3H7

Abstract

The present invention discloses a method for synthesizing a borane compound NH3B3H7. The specific synthesis process is as follows: commercially available (Me4N)B3H8 and I2 are reacted in a solvent THF at -60 to 0 °C to obtain THF·B3H7, and then an excess of NH3 is introduced into the reaction solution at -20 to 40 °C. The precipitated Me4NI is filtered off, and the filtrate is concentrated to obtain a viscous crude product, which is purified to obtain pure NH3B3H7. The operation of the present invention is simple, safe, and has a relatively high yield. It avoids the use of flammable, explosive or air-sensitive raw materials, is suitable for large-scale production in laboratories, and lays a certain material foundation for its further research in hydrogen storage, solid ion conductors and other aspects.

Description

Technical Field

[0001] The present invention belongs to the technical field of the synthesis of borane compounds, and particularly relates to a method for synthesizing a borane compound NH3B3H7. Background Art

[0002] The borane compound NH3B3H7 was first reported by Kodama in 1959. Due to the lack of efficient synthesis methods, there has been less in-depth research on it, especially on its reactivity and applications. Even so, researchers have still discovered its corresponding uses. For example, due to its high hydrogen content, it has great application prospects in the field of hydrogen storage, and it can release hydrogen gently under pyrolysis or hydrolysis conditions (J. Am. Chem. Soc. 2006, 128, 13992; J. Am. Chem. Soc. 2009, 131, 855). In addition to being used as a hydrogen storage material, recently, researchers have found that it can improve the conductivity of solid ion conductors. The potassium ion conductivity of the complex KB3H8·NH3B3H7 is 3-4 orders of magnitude higher than that of KB3H8 under the same conditions (ACS Appl. Mater. Interfaces 2022, 14, 17378). The introduction of NH3B3H7 has greatly improved the potassium ion conductivity of KB3H8. However, due to the limitations of the synthesis method, more in-depth research on NH3B3H7 has been restricted. Therefore, it is necessary to develop simple, safe and efficient synthesis methods to lay a certain material foundation for its more in-depth research in hydrogen storage, solid ion conductors and other aspects.

[0003] Prior to this, there were mainly three synthesis methods for NH3B3H7. One is to heterolytically cleave B4H 10 in an ether solvent to generate B2H6 and R2O·B3H7. When NH3 is introduced into the system, the solvent R2O is replaced to generate the borane NH3B3H7. Another method is to react NaB3H8 and NH4Cl in diethyl ether. After generating [NH4][B3H8], hydrogen can be directly released in situ to generate NH3B3H7. The third method is to react a salt of the anion B3H8 - with an ether solution of HCl or other oxidants, and then introduce NH3 to obtain NH3B3H7. These three synthesis methods seem simple, but they all have certain disadvantages. For the first method, the raw material B4H 10 is a gas at room temperature and will spontaneously combust or explode when exposed to air. Therefore, the use of B4H 10The raw materials pose a great potential safety hazard to the experimenters and are also not conducive to the control of the reaction. Moreover, the by-product B2H6 is also a flammable and explosive gas, which poses higher requirements for the treatment of the reaction tail gas. For the second method, the raw material NaB3H8 will decompose rapidly when exposed to air, which poses relatively high requirements for the anhydrous and anaerobic operation of the experiment. Secondly, when [NH4][B3H8] releases hydrogen in-situ, a large amount of by-products will appear, which causes great difficulties in purifying the prepared NH3B3H7, and at the same time the reproducible yield is relatively low. For the third method, the purification process of the product is relatively complex, generally requiring sublimation or passing through a chromatography column, consuming a large amount of time and having low efficiency, which is not conducive to large-scale synthesis.

[0004] In view of the above deficiencies in the synthesis of NH3B3H7, that is, it is difficult to synthesize in large quantities simply and efficiently. Therefore, it is necessary to design and develop a synthesis method of the borane compound NH3B3H7 with simple operation, safety and high yield, while avoiding the use of flammable, explosive or air-sensitive raw materials, so as to lay a material foundation for its subsequent in-depth research. Summary of the Invention

[0005] The technical problem solved by the present invention is to provide a synthesis method of a borane compound NH3B3H7, which has simple operation, safety, relatively high yield, and can avoid using flammable, explosive or air-sensitive raw materials at the same time.

[0006] The present invention adopts the following technical solution to solve the above technical problem. A synthesis method of a borane compound NH3B3H7, characterized in that the specific process is: commercially available (Me4N)B3H8 and I2 are reacted in a solvent THF (tetrahydrofuran) at -60 to 0 °C to obtain THF·B3H7, and then an excess of NH3 is introduced into the reaction solution at -20 to 40 °C, the generated Me4NI precipitate is filtered off, and the filtrate is concentrated to obtain a viscous crude product, and the crude product is purified to obtain pure NH3B3H7.

[0007] Further preferably, the synthesis method of the borane compound NH3B3H7 is characterized in that the specific steps are as follows: commercially available (Me4N)B3H8 is added to the solvent THF to obtain a THF solution of (Me4N)B3H8, and then I2 is added to the solvent THF to obtain a THF solution of I2. Then, the THF solution of I2 is added dropwise to the THF solution of (Me4N)B3H8, wherein the molar ratio of the feed of (Me4N)B3H8 to I2 is 1.5 - 2.5:1, and the reaction is carried out at -60 to 0 °C for 0.5 - 3 h. After the reaction is completed, an excessive amount of NH3 is introduced into the reaction solution at -20 to 40 °C, and then the formed Me4NI precipitate is filtered off. The filtrate is concentrated to obtain a viscous crude product, which is extracted with a solvent. The extract is concentrated and dried by rotary evaporation to obtain a white solid, which is washed with a solvent and then dried in vacuo to obtain a pure borane product NH3B3H7 with a yield higher than 80%.

[0008] Further preferably, the molar ratio of the feed of (Me4N)B3H8 to I2 is 2:1.

[0009] Further preferably, the solvent for the extraction process is diethyl ether, and the solvent for the washing process is petroleum ether.

[0010] Further preferably, the reaction temperature of (Me4N)B3H8 and I2 is -20 °C, the reaction time is 1 h, and the reaction temperature when introducing an excessive amount of NH3 is 25 °C.

[0011] The reaction equation in the synthesis method of the borane compound NH3B3H7 of the present invention is as follows:

[0012] 2(Me4N)B3H8 + I2 + 2THF = 2THF·B3H7 + 2Me4NI + H2

[0013] THF·B3H7 + NH3 = NH3B3H7 + THF.

[0014] Compared with the prior art, the present invention has the following advantages and beneficial effects: the operation of the present invention is simple, safe, and has a relatively high yield. The purity of the finally obtained product, the borane compound NH3B3H7, is close to 100%. At the same time, the use of flammable, explosive, or air-sensitive raw materials is avoided, which is suitable for large-scale production in the laboratory. Description of the Drawings

[0015] Figure 1 and Figure 2 are respectively the liquid NMR spectra of the product synthesized in Example 1 in deuterated dichloromethane for 11 11B NMR and 1 1H NMR. It can be seen from the figure that the obtained product is a pure borane compound NH3B3H7. Detailed Embodiments

[0016] The above content of the present invention will be further described in detail by way of examples below. However, it should not be understood that the scope of the above subject matter of the present invention is limited to the following examples. Any technology implemented based on the above content of the present invention belongs to the scope of the present invention.

[0017] Example 1

[0018] Commercially available air-stable (Me4N)B3H8 (2.30 g) was charged into a reaction flask, and then 50 mL of THF solvent was added and reserved. At the same time, I2 (2.53 g) was prepared into a 10 mL THF solution of I2 and reserved. Subsequently, the THF solution of I2 was added dropwise to the reaction flask containing (Me4N)B3H8. The reaction was carried out at -60 °C for 3 h. After the reaction was completed, excess NH3 was introduced into the reaction solution at -20 °C. Then the formed Me4NI precipitate was filtered off, and the filtrate was concentrated to obtain a viscous crude product. The crude product was extracted with 50 mL of ether, and the extract was concentrated and dried by rotary evaporation to obtain a white solid. The white solid was further washed once with 20 mL of petroleum ether, and finally dried under vacuum to obtain the borane compound NH3B3H7. The yield was 87%, and its purity was close to 100% by NMR detection.

[0019] Example 2

[0020] Commercially available air-stable (Me4N)B3H8 (2.30 g) was charged into a reaction flask, and then 50 mL of THF solvent was added and reserved. At the same time, I2 (2.53 g) was prepared into a 10 mL THF solution of I2 and reserved. Subsequently, the THF solution of I2 was added dropwise to the reaction flask containing (Me4N)B3H8. The reaction was carried out at -20 °C for 1 h. After the reaction was completed, excess NH3 was introduced into the reaction solution at 25 °C. Then the formed Me4NI precipitate was filtered off, and the filtrate was concentrated to obtain a viscous crude product. The crude product was extracted with 50 mL of ether, and the extract was concentrated and dried by rotary evaporation to obtain a white solid. The white solid was further washed once with 20 mL of petroleum ether, and finally dried under vacuum to obtain the borane compound NH3B3H7. The yield was 93%, and its purity was close to 100% by NMR detection.

[0021] Example 3

[0022] The commercially available air-stable (Me4N)B3H8 (2.30 g) was charged into a reaction flask, and then 50 mL of THF solvent was added and set aside. At the same time, I2 (2.53 g) was prepared into a 10 mL THF solution of I2 and set aside. Subsequently, the THF solution of I2 was added dropwise to the reaction flask containing (Me4N)B3H8. The reaction was carried out at -40 °C for 2 h. After the reaction, an excess of NH3 was introduced into the reaction solution at 0 °C. Then the formed Me4NI precipitate was filtered off, and the filtrate was concentrated to obtain a viscous crude product. The crude product was extracted with 50 mL of diethyl ether, and the extract was concentrated and rotary evaporated to obtain a white solid. The white solid was further washed once with 20 mL of petroleum ether, and finally dried in vacuo to obtain the borane compound NH3B3H7. The yield was 85%, and the purity was close to 100% by NMR detection.

[0023] Example 4

[0024] The commercially available air-stable (Me4N)B3H8 (2.30 g) was charged into a reaction flask, and then 50 mL of THF solvent was added and set aside. At the same time, I2 (2.53 g) was prepared into a 10 mL THF solution of I2 and set aside. Subsequently, the THF solution of I2 was added dropwise to the reaction flask containing (Me4N)B3H8. The reaction was carried out at 0 °C for 0.5 h. After the reaction, an excess of NH3 was introduced into the reaction solution at 40 °C. Then the formed Me4NI precipitate was filtered off, and the filtrate was concentrated to obtain a viscous crude product. The crude product was extracted with 50 mL of diethyl ether, and the extract was concentrated and rotary evaporated to obtain a white solid. The white solid was further washed once with 20 mL of petroleum ether, and finally dried in vacuo to obtain the borane compound NH3B3H7. The yield was 82%, and the purity was close to 100% by NMR detection.

[0025] The above examples describe the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above examples. What is described in the above examples and the specification only illustrates the principle of the present invention. Without departing from the principle of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of protection of the present invention.

Claims

1. A method for synthesizing a borane compound NH3B3H7, characterized in that The specific process is as follows: The commercially available (Me4N)B3H8 reacts with I2 in the solvent THF at -60 to 0 °C to obtain THF·B3H7. Then, an excessive amount of NH3 is introduced into the reaction solution at -20 to 40 °C. The precipitated Me4NI is filtered off, and the filtrate is concentrated to obtain a viscous crude product. The crude product is purified to obtain pure NH3B3H7.

2. The synthesis method of the borane compound NH3B3H7 according to claim 1, characterized in that The specific steps are as follows: The commercially available (Me4N)B3H8 is added to the solvent THF to obtain a THF solution of (Me4N)B3H8. Then, I2 is added to the solvent THF to obtain a THF solution of I2. Subsequently, the THF solution of I2 is added dropwise to the THF solution of (Me4N)B3H8, where the molar ratio of the feed of (Me4N)B3H8 to I2 is 1.5 - 2.5:

1. The reaction is carried out at -60 to 0 °C for 0.5 - 3 h. After the reaction, an excessive amount of NH3 is introduced into the reaction solution at -20 to 40 °C. The precipitated Me4NI is filtered off, and the filtrate is concentrated to obtain a viscous crude product. The crude product is extracted with a solvent, the extract is concentrated and rotary evaporated to obtain a white solid, and the white solid is washed with a solvent and then dried in vacuo to obtain the pure borane product NH3B3H7, with a yield higher than 80%.

3. The synthesis method of the borane compound NH3B3H7 according to claim 1 or 2, characterized in that: The molar ratio of the feed of (Me4N)B3H8 to I2 is 2:

1.

4. The synthesis method of the borane compound NH3B3H7 according to claim 2, characterized in that: The solvent for the extraction process is diethyl ether, and the solvent for the washing process is petroleum ether.

5. The synthesis method of the borane compound NH3B3H7 according to claim 1 or 2, characterized in that: The reaction temperature of (Me4N)B3H8 and I2 is -20 °C, the reaction time is 1 h, and the reaction temperature when introducing excessive NH3 is 25 °C.

6. The synthesis method of the borane compound NH3B3H7 according to claim 1 or 2, characterized in that The reaction equation in the synthesis method of the borane compound NH3B3H7 is as follows: 2(Me4N)B3H8 + I2 + 2THF = 2THF·B3H7 + 2Me4NI + H2 THF·B3H7 + NH3 = NH3B3H7 + THF.

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