Preparation method of boron isotope enriched triethyl borate

Abstract

The invention belongs to the technical field of boron compounds, and particularly relates to a preparation method of boron isotope enriched triethyl borate. The preparation method of the boron isotope-enriched triethyl borate comprises the following steps: reacting boron isotope-enriched boric acid, a metal hydride and ethanol, and after the reaction is completed, carrying out solid-liquid separation and distilling to obtain the boron isotope-enriched triethyl borate. According to the preparation method, boron isotope enriched boric acid solid is taken as a raw material, ethanol is taken as a reaction reagent and solvent, metal hydride is taken as a water removal agent, a reaction byproduct has relatively low solubility in ethanol so as to be easily removed, and the preparation of electronic grade boron isotope enriched triethyl borate can be realized through distillation without a catalyst such as concentrated sulfuric acid; the method does not need to depend on complex manufacturing equipment and purification technology, the synthesis process and the purification process are greatly simplified, and the production cost is reduced.

Description

Technical Field

[0001] This invention relates to the field of boron compound technology, and specifically to a method for preparing boron isotope-enriched triethyl borate. Background Technology

[0002] Boron resource development and utilization still primarily focuses on the bulk product boric acid. With the development of the national economy, accelerating the in-depth development of boron resources in salt lakes, speeding up the development and utilization of high-value-added downstream products of boric acid, and solving the problem of efficient utilization of boron resources in salt lakes are of great significance.

[0003] Boron has two stable isotopes. 10 B and 11 B, 10 B has a relatively low abundance in nature, accounting for only 19.3%. 10 B has a larger absorption cross section for neutrons, 11 B is very small. Because 10 B's excellent properties have led to its widespread application in modern industry and military equipment. In particular, with the development of nuclear power, its usage is continuously increasing. Furthermore... 10 B also has applications in cancer treatment. For 11 B, because it absorbs almost no neutrons, can be used in the semiconductor manufacturing industry. Furthermore, 11 B can also be used in the special steel manufacturing industry to improve the material's high temperature resistance and radiation resistance.

[0004] Boron isotope enrichment can form many compounds, broadly categorized as boron isotope-enriched organoboron compounds, inorganic boron compounds, boron halide compounds, and high-melting-point boron compounds. In recent decades, with the rapid development of the global economy, the demand for boron isotope-enriched products has continuously increased across various sectors, leading to the emergence of new technologies and products. Compared to boron isotope-enriched inorganic boron compounds, boron isotope-enriched organoboron compounds possess unique chemical and physical properties, meeting significant needs in some high-tech fields. Their synthesis and purification technologies are receiving increasing attention.

[0005] Electronic-grade high-purity boron isotope-enriched triethyl borate generally requires an abundance of not less than 99%, a main component content of not less than 99.95%, and a purity of 7N. It can be used not only in the nuclear industry and pharmaceutical industry, but also in the deposition of borosilicate glass (BPSG) during wafer manufacturing. It is an important electronic chemical required for the manufacture of semiconductors, discrete devices, and microelectromechanical systems (MEMS).

[0006] Triethyl borate is generally produced by reacting boric acid and ethanol. However, this reaction produces products of poor quality and low yield. Moreover, this reaction is reversible, and in actual industrial production, concentrated sulfuric acid or other catalysts are usually required to improve reaction efficiency and yield. This results in a large number of byproducts that are difficult to separate and are highly corrosive to equipment. To meet the requirements of electronic-grade triethyl borate, very complex post-processing techniques and equipment are needed. Chinese Patent CN116036633B, published on April 26, 2024, discloses an environmentally friendly and energy-saving preparation method and supporting equipment for electronic-grade triethyl borate. The method uses boric acid and ethanol as raw materials and reacts them with a matching manufacturing equipment to prepare triethyl borate. The manufacturing equipment is arranged in the order of feed to discharge, including a raw material processing component, a crude distillation vessel component, a membrane separation device, and a triple nitrogen-protected distillation vessel component. It eliminates the need for harmful catalysts such as concentrated sulfuric acid and employs different purification technologies to complement each other in impurity removal, making the quality of the finished product more controllable. The method yields electronic-grade triethyl borate with a main distillate purity of 99.99% and a trace impurity content of 8.5N.

[0007] However, the above methods require supporting manufacturing equipment, have long synthesis routes and production cycles, which significantly increase production costs and reduce production efficiency. In addition, the purification technology of this method is very complex, resulting in a very cumbersome production process. Therefore, there is an urgent need for a method for preparing electronic-grade boron isotope-enriched triethyl borate that does not rely on complex manufacturing equipment and has a simple purification process. Summary of the Invention

[0008] This invention provides a method for preparing boron isotope-enriched triethyl borate, which solves the problem that the preparation of electronic-grade boron isotope-enriched triethyl borate requires complex manufacturing equipment and complicated purification processes.

[0009] To solve the above-mentioned technical problems, the technical solution of the preparation method of boron isotope-enriched triethyl borate of the present invention is as follows: A method for preparing boron isotope-enriched triethyl borate includes the following steps: reacting boron isotope-enriched boric acid, metal hydride and ethanol, and obtaining boron isotope-enriched triethyl borate by solid-liquid separation and distillation after the reaction is completed.

[0010] This invention provides an innovative method for preparing boron isotope-enriched triethyl borate, which involves reacting boron isotope-enriched boric acid, a metal hydride, and ethanol. The reaction equation is as follows: n B(OH)3 + 3MH + 3EtOH → nB(OEt)3+3MOH+3H2, utilizing the low solubility of MOH in the ethanol system, the generated MOH exists in the system in solid form, which can be removed by solid-liquid separation. After distillation, electronic-grade boron isotope-enriched triethyl borate with an abundance greater than 99%, a main component content greater than 99.95%, and a purity of 7N can be obtained. The product can be directly applied in the nuclear industry, semiconductor industry, and pharmaceutical industry.

[0011] The preparation method provided by this invention is simple and does not require complex purification techniques and equipment, which greatly simplifies the purification process of electronic-grade triethyl borate and is suitable for large-scale industrial production.

[0012] It is understood that the boron isotope-enriched boric acid described in this invention is a boron-11-enriched solid ( 11 B(OH)3) or enriched boron-10 acid solid ( 10 B(OH)3), the corresponding boron isotope-enriched triethyl borate is boron isotope-enriched triethyl borate-11 (B(OH)3), 11 B(OEt)3) or boron isotope-enriched triethyl boron-10 acid ( 10 B(OEt)3), 11 B(OEt)3 is mainly used in the semiconductor field. 10 B(OEt)3 is mainly used in the nuclear industry and pharmaceutical fields. The high applicability of the preparation method provided by this invention makes the product applicable to a wide range of fields.

[0013] To further improve the yield, preferably, the molar ratio of boron isotope-enriched boric acid, ethanol, and metal hydride is 1:(3~5):(1.5~3). More preferably, the molar ratio of boron isotope-enriched boric acid, ethanol, and metal hydride is 1:(4~4.5):(1.5~2).

[0014] To further improve the yield, the reaction temperature is 60-100°C and the reaction time is 24-48 h. More preferably, the reaction temperature is 80-90°C and the reaction time is 36-40 h.

[0015] To further improve product purity, the distillation preferably includes crude distillation and extractive distillation.

[0016] To further improve purity, preferably, the extractant used in extractive distillation is N,N-dimethylacetamide or N,N-dimethylformamide, with 1-2 mol of extractant added for every 1 mol of boron isotope-enriched boric acid. More preferably, the extractant used in extractive distillation is N,N-dimethylacetamide.

[0017] To further improve purity, preferably, the reflux ratio during extractive distillation is 4-10, and the total reflux time is 30-50 min. More preferably, the reflux ratio during extractive distillation is 6-8, and the total reflux time is 40-50 min.

[0018] To further improve purity, preferably, the extraction solvent is added at a rate of 10-40 g / min. More preferably, the extraction solvent is added at a rate of 20-30 g / min.

[0019] To further improve the removal rate of solid impurities, preferably, the metal hydride is selected from sodium hydride, potassium hydride, and calcium hydride. Attached Figure Description

[0020] Figure 1 This is a flowchart illustrating the preparation method of boron isotope-enriched triethyl borate in Example 1.

[0021] Figure 2 This is a gas chromatogram of commercially available triethyl borate.

[0022] Figure 3 This is a gas chromatogram of boron isotope-enriched triethyl borate from Example 1. Detailed Implementation

[0023] The technical concept of the method for preparing boron isotope-enriched triethyl borate of the present invention is as follows: Currently, triethyl borate is usually synthesized by reacting boric acid and alcohol. However, the product obtained in actual industrial production has low purity, many byproducts, and is difficult to separate. Very complex manufacturing equipment and purification technology are required to meet the requirements of electronic grade triethyl borate.

[0024] This invention uses boron isotope-enriched boric acid solid as raw material, ethanol as reaction reagent and solvent, and metal hydride as dehydrating agent. The reaction generates gas, and the reaction byproducts have low solubility in ethanol, making the byproducts easy to remove. Then, the preparation of electronic-grade boron isotope-enriched triethyl borate can be achieved by distillation. It does not require catalysts such as concentrated sulfuric acid, nor does it rely on complex manufacturing equipment and purification technology, which greatly simplifies the synthesis and purification process and reduces production costs.

[0025] The method for preparing boron isotope-enriched triethyl borate provided by this invention includes the following steps: boron isotope-enriched boric acid, ethanol, and metal hydride in a molar ratio of 1:(3~5):(1.5~3) are reacted at 60~100℃ for 24~48h. The metal hydride is selected from sodium hydride, potassium hydride, and calcium hydride. After the reaction is completed, boron isotope-enriched triethyl borate is obtained by solid-liquid separation, crude distillation, and extractive distillation. The extractant used in the extractive distillation is N,N-dimethylacetamide or N,N-dimethylformamide. 1~2 mol of extractant is added for every 1 mol of boron isotope-enriched boric acid. The reflux ratio during extractive distillation is 4~10, the total reflux time is 30~50 min, and the extraction rate is 10~40 g / min.

[0026] It should be noted that, since the addition of metal hydrides to the reaction system is exothermic, the preparation method provided by this invention involves first mixing boron isotope-enriched boric acid and ethanol, and then adding the metal hydrides in batches to ensure that the system temperature does not exceed 40°C. The reaction time refers to the time required for the reaction to occur after the metal hydrides have been completely added.

[0027] In a specific embodiment, the mixing involves stirring boron isotope-enriched boric acid and ethanol at room temperature for 1-2 hours.

[0028] In a specific embodiment, the reaction is carried out under a protective atmosphere, which is an inert atmosphere.

[0029] In a specific implementation, the solid-liquid separation is filtration.

[0030] In a specific embodiment, the temperature of the crude distillation is 130~150℃.

[0031] In a specific embodiment, the temperature at which the extractant is added during the extractive distillation is 160~180℃.

[0032] In a specific embodiment, the fraction collected at 117-118℃ during extractive distillation yields boron isotope-enriched triethyl borate.

[0033] In a specific implementation, gas chromatography-mass spectrometry is used to qualitatively and quantitatively analyze the boron isotopes in the product to enrich triethyl borate.

[0034] The present invention will now be described in detail with reference to specific embodiments. The raw materials used in the following embodiments are all commercially available products and are well-known to those skilled in the art.

[0035] I. Specific Examples of the Preparation Method of Boron Isotope-Enriched Triethyl Borate of the Present Invention Example 1 The flowchart of the preparation method of boron isotope-enriched triethyl borate in this embodiment is as follows: Figure 1 As shown, the specific method is as follows: Under a nitrogen atmosphere, boron-10 acid solid was added to the reaction flask. 10 B(OH)3 (680 g, 10 mol) and ethanol (1843 g, 40 mol) were stirred at room temperature for 1 hour. Then, calcium hydride (630 g, 15 mol) was added in batches to keep the system temperature below 40°C, and the reaction was carried out at 80°C for 36 hours. After the reaction, the mixture was cooled to room temperature, the solid precipitate was filtered off, and the product was distilled at 130°C (crude distillation) to obtain crude triethyl borate enriched with boron isotopes. The crude product was added to an extractive distillation apparatus and heated to 160°C. Then, N,N-dimethylacetamide (870 g, 10 mol) was added at a flow rate of 20 g / min and refluxed for 50 min to achieve vapor-liquid equilibrium. The reflux ratio was set to 6 (the ratio of reflux to product in the entire distillation system). The fraction collected at 117-118°C was finally obtained as 1100 g of triethyl borate-10. The yield was 75%, with a content >99.99% (content refers to the percentage of triethyl borate in the product, quantitatively determined by gas chromatography), and a purity >99.99999% (purity refers to the content of triethyl borate obtained after removing all metal impurity ions and anions from the product; the content of metal impurity ions was detected by inductively coupled plasma mass spectrometry (ICP-MS), and the content of anions was detected by ion chromatography). The separated extractant N,N-dimethylacetamide can be recycled for extractive distillation.

[0036] The gas chromatograms of commercially available triethyl borate and the triethyl borate-10 obtained in this example are shown below. Figure 2 and Figure 3 As shown, spectral peaks can be clearly seen at the same positions, proving that boron isotope-enriched triethyl borate was successfully prepared in this embodiment.

[0037] Example 2 The preparation method of boron isotope-enriched triethyl borate in this embodiment is as follows: Under a nitrogen atmosphere, boron-11 acid solid was added to the reaction flask. 11B(OH)3 (680 g, 10 mol) and ethanol (1843 g, 40 mol) were stirred at room temperature for 1 hour. Then, calcium hydride (630 g, 15 mol) was added in batches to keep the system temperature below 40°C, and the reaction was carried out at 80°C for 36 hours. After the reaction, the mixture was cooled to room temperature, the solid precipitate was filtered off, and the product was distilled at 130°C to obtain crude triethyl borate enriched by boron isotopes. The crude product was added to an extractive distillation apparatus and heated to 160°C. Then, N,N-dimethylacetamide (870 g, 10 mol) was added at a flow rate of 20 g / min and refluxed for 50 min to achieve gas-liquid equilibrium. The reflux ratio was set to 6, and the fraction collected at 117-118°C was used to finally obtain 1120 g of triethyl borate, with a yield of 77%, a content >99.99%, and a purity >99.99999%.

[0038] Example 3 The preparation method of boron isotope-enriched triethyl borate in this embodiment is as follows: Under a nitrogen atmosphere, boron-11 acid solid was added to the reaction flask. 11 B(OH)3 (680 g, 10 mol) and ethanol (1382 g, 30 mol) were stirred at room temperature for 1 hour. Then, calcium hydride (630 g, 15 mol) was added in batches to keep the system temperature below 40°C, and the reaction was carried out at 80°C for 36 hours. After the reaction was complete, the mixture was cooled to room temperature, the solid precipitate was filtered off, and the product was distilled at 130°C to obtain crude boron isotope-enriched triethyl borate. The crude product was added to an extractive distillation apparatus and heated to 160°C. Then, N,N-dimethylacetamide (870 g, 10 mol) was added at a flow rate of 20 g / min and refluxed for 50 min to achieve gas-liquid equilibrium. The reflux ratio was set to 6, and the fraction collected at 117-118°C yielded 840 g of triethyl borate, with a yield of 58%, a content >99.99%, and a purity >99.99999%.

[0039] Example 4 The preparation method of boron isotope-enriched triethyl borate in this embodiment is as follows: Under a nitrogen atmosphere, boron-11 acid solid was added to the reaction flask. 11B(OH)3 (680 g, 10 mol) and ethanol (2303 g, 50 mol) were stirred at room temperature for 1 hour. Then, calcium hydride (630 g, 15 mol) was added in batches to keep the system temperature below 40°C, and the reaction was carried out at 80°C for 36 hours. After the reaction was complete, the mixture was cooled to room temperature, the solid precipitate was filtered off, and the product was distilled at 130°C to obtain crude boron isotope-enriched triethyl borate. The crude product was added to an extractive distillation apparatus and heated to 160°C. Then, N,N-dimethylacetamide (870 g, 10 mol) was added at a flow rate of 20 g / min and refluxed for 50 min to achieve gas-liquid equilibrium. The reflux ratio was set to 6, and the fraction collected at 117-118°C yielded 960 g of triethyl borate, with a yield of 66%, a content >99.99%, and a purity >99.99999%.

[0040] Example 5 The preparation method of boron isotope-enriched triethyl borate in this embodiment is as follows: Under a nitrogen atmosphere, boron-11 acid solid was added to the reaction flask. 11 B(OH)3 (680 g, 10 mol) and ethanol (1843 g, 40 mol) were stirred at room temperature for 1 hour. Then, sodium hydride (720 g, 30 mol) was added in batches to keep the system temperature below 40°C, and the reaction was carried out at 80°C for 36 hours. After the reaction was complete, the mixture was cooled to room temperature, the solid precipitate was filtered off, and the product was distilled at 130°C to obtain crude triethyl borate enriched by boron isotopes. The crude product was added to an extractive distillation apparatus and heated to 160°C. Then, N,N-dimethylacetamide (870 g, 10 mol) was added at a flow rate of 20 g / min and refluxed for 50 min to achieve gas-liquid equilibrium. The reflux ratio was set to 6, and the fraction collected at 117-118°C yielded 890 g of triethyl borate, with a yield of 61%, a content >99.99%, and a purity >99.99999%.

[0041] Example 6 The preparation method of boron isotope-enriched triethyl borate in this embodiment is as follows: Under a nitrogen atmosphere, boron-11 acid solid was added to the reaction flask. 11B(OH)3 (680 g, 10 mol) and ethanol (1843 g, 40 mol) were stirred at room temperature for 1 hour. Potassium hydride (1200 g, 30 mol) was then added in batches to keep the system temperature below 40°C, and the reaction was carried out at 80°C for 36 hours. After the reaction was complete, the mixture was cooled to room temperature, the solid precipitate was filtered off, and the product was distilled at 130°C to obtain crude boron isotope-enriched triethyl borate. The crude product was added to an extractive distillation apparatus and heated to 160°C. Then, N,N-dimethylacetamide (870 g, 10 mol) was added at a flow rate of 20 g / min and refluxed for 50 min to achieve gas-liquid equilibrium. The reflux ratio was set to 6, and the fraction collected at 117-118°C yielded 790 g of triethyl borate, with a yield of 54%, a content >99.99%, and a purity >99.99999%.

[0042] Example 7 The preparation method of boron isotope-enriched triethyl borate in this embodiment is as follows: Under a nitrogen atmosphere, boron-11 acid solid was added to the reaction flask. 11 B(OH)3 (680 g, 10 mol) and ethanol (1843 g, 40 mol) were stirred at room temperature for 1 hour. Then, calcium hydride (630 g, 15 mol) was added in batches to keep the system temperature below 40°C, and the reaction was carried out at 60°C for 36 hours. After the reaction was complete, the mixture was cooled to room temperature, the solid precipitate was filtered off, and the product was distilled at 130°C to obtain crude triethyl borate enriched by boron isotopes. The crude product was added to an extractive distillation apparatus and heated to 160°C. Then, N,N-dimethylacetamide (870 g, 10 mol) was added at a flow rate of 20 g / min and refluxed for 50 min to achieve gas-liquid equilibrium. The reflux ratio was set to 6, and the fraction collected at 117-118°C was used to finally obtain 1010 g of triethyl borate, with a yield of 69%, a content >99.99%, and a purity >99.99999%.

[0043] Example 8 The preparation method of boron isotope-enriched triethyl borate in this embodiment is as follows: Under a nitrogen atmosphere, boron-11 acid solid was added to the reaction flask. 11B(OH)3 (680 g, 10 mol) and ethanol (1843 g, 40 mol) were stirred at room temperature for 1 hour. Then, calcium hydride (630 g, 15 mol) was added in batches to keep the system temperature below 40°C, and the reaction was carried out at 100°C for 36 hours. After the reaction was complete, the mixture was cooled to room temperature, the solid precipitate was filtered off, and the product was distilled at 130°C to obtain crude triethyl borate enriched by boron isotopes. The crude product was added to an extractive distillation apparatus and heated to 160°C. Then, N,N-dimethylacetamide (870 g, 10 mol) was added at a flow rate of 20 g / min and refluxed for 50 min to achieve gas-liquid equilibrium. The reflux ratio was set to 6, and the fraction collected at 117-118°C was used to finally obtain 1100 g of triethyl borate, with a yield of 75%, a content >99.99%, and a purity >99.99999%.

[0044] Example 9 The preparation method of boron isotope-enriched triethyl borate in this embodiment is as follows: Under a nitrogen atmosphere, boron-11 acid solid was added to the reaction flask. 11 B(OH)3 (680 g, 10 mol) and ethanol (1843 g, 40 mol) were stirred at room temperature for 1 hour. Then, calcium hydride (630 g, 15 mol) was added in batches to keep the system temperature below 40°C, and the reaction was carried out at 80°C for 24 hours. After the reaction was complete, the mixture was cooled to room temperature, the solid precipitate was filtered off, and the product was distilled at 130°C to obtain crude triethyl borate enriched by boron isotopes. The crude product was added to an extractive distillation apparatus and heated to 160°C. Then, N,N-dimethylacetamide (870 g, 10 mol) was added at a flow rate of 20 g / min and refluxed for 50 min to achieve gas-liquid equilibrium. The reflux ratio was set to 6, and the fraction collected at 117-118°C yielded 880 g of triethyl borate, with a yield of 60%, a content >99.99%, and a purity >99.99999%.

[0045] Example 10 The preparation method of boron isotope-enriched triethyl borate in this embodiment is as follows: Under a nitrogen atmosphere, boron-11 acid solid was added to the reaction flask. 11B(OH)3 (680 g, 10 mol) and ethanol (1843 g, 40 mol) were stirred at room temperature for 1 hour. Then, calcium hydride (630 g, 15 mol) was added in batches to keep the system temperature below 40°C, and the reaction was carried out at 80°C for 48 hours. After the reaction was complete, the mixture was cooled to room temperature, the solid precipitate was filtered off, and the product was distilled at 130°C to obtain crude triethyl borate enriched by boron isotopes. The crude product was added to an extractive distillation apparatus and heated to 160°C. Then, N,N-dimethylacetamide (870 g, 10 mol) was added at a flow rate of 20 g / min and refluxed for 50 min to achieve gas-liquid equilibrium. The reflux ratio was set to 6, and the fraction collected at 117-118°C yielded 1100 g of triethyl borate, with a yield of 75%, a content >99.99%, and a purity >99.99999%.

[0046] Example 11 The preparation method of boron isotope-enriched triethyl borate in this embodiment is as follows: Under a nitrogen atmosphere, boron-11 acid solid was added to the reaction flask. 11 B(OH)3 (680 g, 10 mol) and ethanol (1843 g, 40 mol) were stirred at room temperature for 1 hour. Then, calcium hydride (630 g, 15 mol) was added in batches to keep the system temperature below 40°C, and the reaction was carried out at 80°C for 36 hours. After the reaction was complete, the mixture was cooled to room temperature, the solid precipitate was filtered off, and the product was distilled at 130°C to obtain crude boron isotope-enriched triethyl borate. The crude product was added to an extractive distillation apparatus and heated to 160°C. Then, N,N-dimethylformamide (730 g, 10 mol) was added at a flow rate of 20 g / min and refluxed for 50 min to achieve gas-liquid equilibrium. The reflux ratio was set to 6, and the fraction collected at 117-118°C yielded 1050 g of triethyl borate, with a yield of 72%, a content >99.9%, and a purity >99.999%.

[0047] Example 12 The preparation method of boron isotope-enriched triethyl borate in this embodiment is as follows: Under a nitrogen atmosphere, boron-11 acid solid was added to the reaction flask. 11B(OH)3 (680 g, 10 mol) and ethanol (1843 g, 40 mol) were stirred at room temperature for 1 hour. Then, calcium hydride (630 g, 15 mol) was added in batches to keep the system temperature below 40°C, and the reaction was carried out at 80°C for 36 hours. After the reaction, the mixture was cooled to room temperature, the solid precipitate was filtered off, and the product was distilled at 130°C to obtain crude boron isotope-enriched triethyl borate. The crude product was added to an extractive distillation apparatus and heated to 160°C. Then, N,N-dimethylacetamide (870 g, 10 mol) was added at a flow rate of 10 g / min and refluxed for 50 min to achieve gas-liquid equilibrium. The reflux ratio was set to 6, and the fraction collected at 117-118°C yielded 1110 g of triethyl borate, with a yield of 76%, a content >99.9%, and a purity >99.9999%.

[0048] Example 13 The preparation method of boron isotope-enriched triethyl borate in this embodiment is as follows: Under a nitrogen atmosphere, boron-11 acid solid was added to the reaction flask. 11 B(OH)3 (680 g, 10 mol) and ethanol (1843 g, 40 mol) were stirred at room temperature for 1 hour. Then, calcium hydride (630 g, 15 mol) was added in batches to keep the system temperature below 40°C, and the reaction was carried out at 80°C for 36 hours. After the reaction was completed, the mixture was cooled to room temperature, the solid precipitate was filtered off, and the product was distilled at 130°C to obtain crude boron isotope-enriched triethyl borate. The crude product was added to an extractive distillation apparatus and heated to 160°C. Then, N,N-dimethylacetamide (870 g, 10 mol) was added at a flow rate of 40 g / min and refluxed for 50 min to achieve gas-liquid equilibrium. The reflux ratio was set to 6, and the fraction collected at 117-118°C was collected. Finally, 1100 g of triethyl borate was obtained, with a yield of 75%, a content >99.9%, and a purity >99.9999%.

[0049] Example 14 The preparation method of boron isotope-enriched triethyl borate in this embodiment is as follows: Under a nitrogen atmosphere, boron-11 acid solid was added to the reaction flask. 11B(OH)3 (680 g, 10 mol) and ethanol (1843 g, 40 mol) were stirred at room temperature for 1 hour. Then, calcium hydride (630 g, 15 mol) was added in batches to keep the system temperature below 40°C, and the reaction was carried out at 80°C for 36 hours. After the reaction, the mixture was cooled to room temperature, the solid precipitate was filtered off, and the product was distilled at 130°C to obtain crude boron isotope-enriched triethyl borate. The crude product was added to an extractive distillation apparatus and heated to 160°C. Then, N,N-dimethylacetamide (870 g, 10 mol) was added at a flow rate of 20 g / min and refluxed for 30 min to achieve gas-liquid equilibrium. The reflux ratio was set to 6, and the fraction collected at 117-118°C was used to finally obtain 1120 g of triethyl borate, with a yield of 77%, a content >99.9%, and a purity >99.999%.

[0050] Example 15 The preparation method of boron isotope-enriched triethyl borate in this embodiment is as follows: Under a nitrogen atmosphere, boron-11 acid solid was added to the reaction flask. 11 B(OH)3 (680 g, 10 mol) and ethanol (1843 g, 40 mol) were stirred at room temperature for 1 hour. Then, calcium hydride (630 g, 15 mol) was added in batches to keep the system temperature below 40°C, and the reaction was carried out at 80°C for 36 hours. After the reaction was completed, the mixture was cooled to room temperature, the solid precipitate was filtered off, and the product was distilled at 130°C to obtain crude boron isotope-enriched triethyl borate. The crude product was added to an extractive distillation apparatus and heated to 160°C. Then, N,N-dimethylacetamide (870 g, 10 mol) was added at a flow rate of 20 g / min and refluxed for 50 min to achieve gas-liquid equilibrium. The reflux ratio was set to 4, and the fraction collected at 117-118°C was collected. Finally, 1100 g of triethyl borate was obtained, with a yield of 75%, a content >99.9%, and a purity >99.999%.

[0051] Example 16 The preparation method of boron isotope-enriched triethyl borate in this embodiment is as follows: Under a nitrogen atmosphere, boron-11 acid solid was added to the reaction flask. 11B(OH)3 (680 g, 10 mol) and ethanol (1843 g, 40 mol) were stirred at room temperature for 1 hour. Then, calcium hydride (630 g, 15 mol) was added in batches to keep the system temperature below 40°C, and the reaction was carried out at 80°C for 36 hours. After the reaction was complete, the mixture was cooled to room temperature, the solid precipitate was filtered off, and the product was distilled at 130°C to obtain crude triethyl borate enriched by boron isotopes. The crude product was added to an extractive distillation apparatus and heated to 160°C. Then, N,N-dimethylacetamide (870 g, 10 mol) was added at a flow rate of 20 g / min and refluxed for 50 min to achieve gas-liquid equilibrium. The reflux ratio was set to 10, and the fraction collected at 117-118°C yielded 1050 g of triethyl borate, with a yield of 72%, a content >99.9%, and a purity >99.9999%.

[0052] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing boron isotope-enriched triethyl borate, characterized in that, Includes the following steps: Boron isotope-enriched boric acid, metal hydride, and ethanol were reacted, and after the reaction was completed, boron isotope-enriched triethyl borate was obtained by solid-liquid separation and distillation.

2. The method for preparing boron isotope-enriched triethyl borate as described in claim 1, characterized in that, The molar ratio of the boron isotope-enriched boric acid, ethanol, and metal hydride is 1:(3~5):(1.5~3).

3. The method for preparing boron isotope-enriched triethyl borate as described in claim 1 or 2, characterized in that, The molar ratio of the boron isotope-enriched boric acid, ethanol, and metal hydride is 1:(4~4.5):(1.5~2).

4. The method for preparing boron isotope-enriched triethyl borate as described in claim 1, characterized in that, The reaction temperature is 60~100℃, and the reaction time is 24~48h.

5. The method for preparing boron isotope-enriched triethyl borate as described in claim 1, characterized in that, The distillation includes crude distillation and extractive distillation.

6. The method for preparing boron isotope-enriched triethyl borate as described in claim 5, characterized in that, The extractant used in extractive distillation is N,N-dimethylacetamide or N,N-dimethylformamide. For every 1 mol of boron isotope enriched with boric acid, 1-2 mol of extractant is added.

7. The method for preparing boron isotope-enriched triethyl borate as described in claim 5, characterized in that, The reflux ratio during extractive distillation is 4-10, and the total reflux time is 30-50 min.

8. The method for preparing boron isotope-enriched triethyl borate as described in claim 7, characterized in that, The reflux ratio during extractive distillation is 6-8, and the total reflux time is 40-50 min.

9. The method for preparing boron isotope-enriched triethyl borate as described in claim 6, characterized in that, The extraction solvent is added at a rate of 10~40 g / min.

10. The method for preparing boron isotope-enriched triethyl borate as described in claim 1, characterized in that, The metal hydride is selected from one of sodium hydride, potassium hydride, and calcium hydride.

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