Method for producing high-purity butoxydibutylborane

Abstract

The present invention discloses a method for producing butoxydibutylborane, comprising the step of introducing a gas raw material containing oxygen gas into a reaction vessel containing n-tributylborane raw material, and oxidizing the n-tributylborane to produce butoxydibutylborane, wherein the gas raw material is a mixed gas of an inert gas and air. The method of the present invention allows for the easy production of high-purity butoxydibutylborane, and can obtain butoxydibutylborane with a purity of 95% or more and a yield of 90% or more without requiring a distillation purification step. The butoxydibutylborane has good flammability and high polymerization activity and can be used as a polymerization initiator for hard tissue adhesives in dentistry, orthopedics, etc.

Description

Reference to Related Applications

[0001] This application claims the rights and priority of a Chinese invention patent application with the application number 202310289704.4 and the invention title "Method for Producing High-Purity Butoxydibutylborane", which was filed on March 16, 2023. All the contents of the Chinese patent application are incorporated herein by reference.

Technical Field

[0002] The present invention relates to an organic boron compound applied as a polymerization initiator for adhesives for hard tissue repair, and specifically, to a method for producing high-purity butoxydibutylborane.

Background Art

[0003] Acrylic adhesives using an organic boron compound as a polymerization initiator are widely used for hard tissue adhesion because of their low toxicity and high adhesive strength. Tributylborane is a polymerization initiator known in the art that can be used in the production of adhesives for hard tissue repair such as dentistry. Tributylborane is extremely unstable in air and reacts rapidly with oxygen and catches fire when exposed to air, so it is not suitable for normal clinical use. Therefore, researchers have been working hard on research on how to improve the ignition safety of tributylborane.

[0004] Japanese Patent Document JP-A-48-5143 (Masahara et al.) discloses reacting pure oxygen gas with tributylborane to produce partially oxidized tributylborane and using it as a polymerization initiator for dental or surgical adhesives. Although the partially oxidized tributylborane has improved the ignition safety of tributylborane to some extent, it has not been able to completely suppress the flammability. And the reaction between pure oxygen gas and tributylborane is very intense and difficult to control, and there is also a certain risk in the reaction process.

[0005] Subsequently, in a paper published in 1978 (Development of adhesive pit and fissure sealants using a MMA resin initiated by a tri-n-butyl borane derivative, Journal of Biomedical Materials Research, Vol 12, 149-165), Masuhara et al. further improved the reaction of pure oxygen gas and tributylborane disclosed in the Japanese patent document mentioned above, reacting tributylborane with air to produce partially oxidized tributylborane, which was used as a polymerization initiator for dental adhesives. Changing the oxygen source to air mitigated the potential dangers of the violent reaction to some extent, but the resulting butoxydibutylborane had low purity and still could not completely suppress its flammability.

[0006] Chinese patent document CN113332486A discloses a method for obtaining butoxydibutylborane by reacting tributylborane with butanol, or by reacting tributylborane with air to obtain butoxydibutylborane, and then obtaining high-purity butoxydibutylborane by distillation purification of the obtained butoxydibutylborane, thereby providing a polymerization initiator with improved flammability. However, this technique requires additional distillation purification, resulting in multiple steps and a low recovery rate of the target product.

[0007] Therefore, there is a pressing need in this field for a method to produce high-purity butoxydibutylborane, the resulting butoxydibutylborane having a purity that directly meets the application requirements as a polymerization initiator for hard tissue repair adhesives, while simultaneously possessing improved flammability, ease of use, and biocompatibility. [Overview of the project]

[0008] In one aspect of the present invention, a method for producing high-purity butoxydibutylborane is provided, comprising the step of introducing a gas raw material containing oxygen gas into a reaction vessel containing a liquid n-tributylborane raw material, and oxidizing the n-tributylborane to produce butoxydibutylborane, without requiring an additional purification step, wherein the gas raw material is a mixed gas of an inert gas and air.

[0009] In some embodiments of the first aspect of the present invention, the volume ratio of the inert gas to air is 0.7 or greater.

[0010] In some embodiments of the first aspect of the present invention, the volume ratio of the inert gas to air is 0.7 to 2.

[0011] In some embodiments of the first aspect of the present invention, the volume ratio of the inert gas to air is 1 to 2.

[0012] In some embodiments of the first aspect of the present invention, the molar ratio of oxygen gas to n-tributylborane contained in the introduced mixed gas is 0.44 to 0.6.

[0013] In some embodiments of the first aspect of the present invention, the supply flow rate of oxygen gas in the mixed gas is 0.86 L / h or less per 1 mol of n-tributylborane raw material.

[0014] In some embodiments of the first aspect of the present invention, the supply flow rate of oxygen gas in the mixed gas is 0.43 L / h to 0.57 L / h per 1 mol of n-tributylborane raw material.

[0015] In some embodiments of the first aspect of the present invention, the inert gas is selected from nitrogen gas, helium gas, neon gas, and argon gas. In an exemplary embodiment of the present invention, the inert gas is nitrogen gas.

[0016] In some embodiments of the first aspect of the present invention, the purity of the target product butoxydibutylborane, which is produced by the oxidation reaction of n-tributylborane, is 95% or higher.

[0017] In a second aspect of the present invention, butoxydibutylborane produced by the method described in the first aspect of the present invention is provided.

[0018] In a third aspect of the present invention, the use of butoxydibutylborane, produced by the method described in the first aspect of the present invention, as a polymerization initiator for producing adhesives for hard tissue repair is provided.

[0019] Compared to the prior art, the present invention has the following beneficial technical effects. Specifically, the method for producing butoxydibutylborane of the present invention uses a mixed gas consisting of an inert gas (e.g., nitrogen gas) and air as gaseous raw materials, and by an oxidation reaction with liquid tributylborane, high-purity butoxydibutylborane can be easily produced, and a target product butoxydibutylborane with a purity of 95% or more and a yield of 90% or more can be obtained without requiring an additional distillation purification step. Such high-purity butoxydibutylborane has good flammability and high polymerization activity, and can meet the requirements for use as a polymerization initiator in hard tissue adhesives such as dental and orthodontic adhesives without requiring additional distillation purification. [Modes for carrying out the invention]

[0020] The following will provide a detailed explanation of the various aspects to which the present invention relates by combining specific examples. However, these specific examples are merely illustrative and do not limit the scope of protection or the substantial content of the present invention.

[0021] In the manufacturing method of the present invention, a mixed gas of an inert gas and air is used as the gas raw material for supplying oxygen gas. The inert gas is a gas that does not chemically react with the n-tributylborane raw material, such as nitrogen gas or a noble gas. In the exemplary embodiments described later, nitrogen gas may be used as the inert gas, or other inert gases or combinations thereof may be used.

[0022] Through research, this invention has been found to yield high-purity butoxydibutylborane through a gas-liquid reaction with n-tributylborane when the volume ratio of the inert gas to air in the gas mixture is controlled to 0.7 or higher. Increasing the proportion of the inert gas in the gas mixture is advantageous for further improving the purity of the product, but if the volume ratio of the inert gas to air exceeds 2, although a high-purity product can still be obtained, the proportion of oxygen gas participating in the reaction in the gas mixture decreases. Therefore, from the viewpoint of production efficiency, production efficiency is too low when the volume ratio of the inert gas to air exceeds 2. Accordingly, considering both product purity and reaction efficiency, the volume ratio of the inert gas to air in the gas mixture can be selected from 0.7 to 2.

[0023] In the manufacturing method of the present invention, the molar ratio of oxygen gas to n-tributylborane contained in the mixed gas is 0.44 to 0.6, and this ratio allows the two to undergo a sufficient chemical reaction. By controlling the supply flow rate of oxygen gas in the mixed gas, the purity of the target product, butoxydibutylborane, can be further controlled. The supply rate of the mixed gas should ensure that the amount of oxygen gas contained therein is sufficient to undergo a sufficient chemical reaction with n-tributylborane within the gas supply period to obtain the target product, butoxydibutylborane. Reducing the oxygen gas supply flow rate is advantageous for improving the purity of the target product, butoxydibutylborane, but it reduces the manufacturing efficiency. Therefore, considering the purity of the target product and the manufacturing efficiency, the supply rate of the mixed gas in the present invention is controlled so that the supply flow rate of oxygen gas in the mixed gas is 0.86 L / h or less per 1 mol of n-tributylborane raw material. In the exemplary examples described later, the supply flow rate of oxygen gas in the mixed gas is 0.43 L / h to 0.57 L / h.

[0024] In the production method of the present invention, the temperature of the reactant n-tributylborane may be 15°C to 80°C, and in the exemplary examples described later, the temperature of the reactant n-tributylborane is 40°C.

[0025] Example 1 The method for producing butoxydibutylborane in this example includes the following steps. That is, in a nitrogen gas atmosphere, 182 g (equivalent to 1 mol) of n-tributylborane is injected into a reactor, and the temperature of the reactants is maintained at 40 °C or lower by a water bath. While stirring the liquid n-tributylborane, a mixed gas of dry nitrogen gas and air is introduced into it. In the mixed gas, the volume ratio of nitrogen gas / air is 1 / 1. The supply flow rate of oxygen gas in the mixed gas is 0.57 L / h, the gas supply period is 9 hours, and the total supply amount of oxygen gas reaches 0.5 mol. In other words, the input amount of the mixed gas is such that the molar ratio of the oxygen gas contained therein to n-tributylborane is 0.5. Then, the reactant container is kept at room temperature under reduced pressure (1 to 2 mmHg) for 2 hours, and 184.8 g of the target product is obtained. By gas chromatography, the target product is confirmed to be butoxydibutylborane with a purity of 96.1%. By calculation, the yield of the target product is 93.3%. Refer to Table 1 below.

[0026] Example 2 The difference between Example 2 and Example 1 is that the supply flow rate of oxygen gas in the mixed gas is 0.43 L / h, the input period of the mixed gas is extended to 12 hours, and the amount of oxygen gas in the introduced mixed gas is maintained at 0.5 mol. In Example 2, 186.7 g of the target product is produced. By gas chromatography, the target product is confirmed to be butoxydibutylborane with a purity of 97.1%. By calculation, the yield of the target product is 94.2%. Refer to Table 1 below.

[0027] Example 3 The difference between Example 3 and Example 1 is that the volume ratio of nitrogen gas to air in the mixed gas is 0.7:1. The input period of the mixed gas is still 9 hours, and the amount of oxygen gas in the introduced mixed gas is still maintained at 0.5 mol. In Example 3, 182.5 g of the target product is produced. By gas chromatography, the target product is confirmed to be butoxydibutylborane with a purity of 95.6%. By calculation, the yield of the target product is 92.1%. Refer to Table 1 below.

[0028] Example 4 The difference between Example 4 and Example 1 is that the volume ratio of nitrogen gas to air in the mixed gas is 0.8:1. The input period of the mixed gas is still 9 hours, and the amount of oxygen gas in the input mixed gas remains 0.5 mol. In Example 4, 183 g of the target product was produced. By gas chromatography, the target product was confirmed to be butoxydibutylborane with a purity of 95.7%. By calculation, the yield of the target product was 92.4%. Refer to Table 1 below.

[0029] Example 5 The difference between Example 5 and Example 1 is that the volume ratio of nitrogen gas to air in the mixed gas is 1.5:1. The input period of the mixed gas is still 9 hours, and the amount of oxygen gas in the input mixed gas remains 0.5 mol. In Example 5, 186.7 g of the target product was produced. By gas chromatography, the target product was confirmed to be butoxydibutylborane with a purity of 97.1%. By calculation, the yield of the target product was 94.2%. Refer to Table 1 below.

[0030] Example 6 The difference between Example 6 and Example 1 is that the volume ratio of nitrogen gas to air in the mixed gas is 1.5:1, the supply flow rate of oxygen gas in the input mixed gas is 0.43 L / h, the input period of the mixed gas is extended to 12 hours, and the amount of oxygen gas in the input mixed gas is maintained at 0.5 mol. In Example 6, 187 g of the target product was produced. By gas chromatography, the target product was confirmed to be butoxydibutylborane with a purity of 97.3%. By calculation, the yield of the target product was 94.4%. Refer to Table 1 below.

[0031] Example 7 The difference between Example 7 and Example 1 is that the volume ratio of nitrogen gas to air in the gas mixture was 2:1. The gas mixture was still introduced for 9 hours, and the amount of oxygen gas in the introduced gas mixture was still maintained at 0.5 mol. In Example 7, 187 g of the target product was produced, and gas-phase chromatography confirmed that the target product was butoxydibutylborane with a purity of 97.5%. By calculation, the yield of the target product was 94.4%. See Table 1 below.

[0032] Example 8 The difference between Example 8 and Example 1 is that the volume ratio of nitrogen gas to air in the gas mixture was 2:1, the oxygen gas supply flow rate in the introduced gas mixture was 0.43 L / h, the introduction period of the gas mixture was extended to 12 hours, and the amount of oxygen gas in the introduced gas mixture was maintained at 0.5 mol. In Example 8, 187.3 g of the target product was produced, and gas-phase chromatography confirmed that the target product was butoxydibutylborane with a purity of 97.6%. By calculation, the yield of the target product was 94.5%. See Table 1 below.

[0033] Example 9 In Example 9, the volume ratio of nitrogen gas to air in the gas mixture was maintained at 1:1. The difference from Example 1 was that the oxygen gas supply flow rate in the introduced gas mixture was 0.57 L / h, the introduction period of the gas mixture was 8 hours, and the amount of oxygen gas in the introduced gas mixture was 0.44 mol. In Example 9, 185.5 g of the target product was produced, and gas-phase chromatography confirmed that the target product was butoxydibutylborane with a purity of 95.1%. By calculation, the yield of the target product was 93.6%. See Table 1 below.

[0034] Example 10 In Example 10, the volume ratio of nitrogen gas to air in the gas mixture was maintained at 1:1. The difference from Example 1 was that the oxygen gas supply flow rate in the introduced gas mixture was 0.57 L / h, the introduction period of the gas mixture was 10.8 hours, and the amount of oxygen gas in the introduced gas mixture was 0.6 mol. In Example 10, 179.1 g of the target product was produced, and gas-phase chromatography confirmed that the target product was butoxydibutylborane with a purity of 95.2%. By calculation, the yield of the target product was 90.4%. See Table 1 below.

[0035] To more clearly demonstrate the beneficial effects of butoxydibutylborane produced in this invention, Comparative Examples 1 to 8 are provided here, specifically as follows.

[0036] Comparative Example 1 The only difference between Comparative Example 1 and Example 1 is that the volume ratio of nitrogen gas to air in the gas mixture is 0.5:1. The butoxydibutylborane produced by this comparative example was found to have a purity of 90.3% by relative area analysis using gas-phase chromatography. Calculations revealed a yield of 89.5%. See Table 1 below.

[0037] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is that the volume ratio of nitrogen gas to air in the mixed gas is 0.7:1, the supply flow rate of oxygen gas in the introduced mixed gas is 0.86 L / h, the introduction period of the mixed gas is shortened to 6 hours, and the amount of oxygen gas in the introduced mixed gas is maintained at 0.5 mol. The butoxydibutylborane produced in Comparative Example 2 was found to have a purity of 90.8% by relative area analysis of gas-phase chromatography. The yield was calculated to be 90.2%. See Table 1 below.

[0038] Comparative Example 3 The difference between Comparative Example 3 and Example 1 is that the volume ratio of nitrogen gas to air in the mixed gas is 1:1, the supply flow rate of oxygen gas in the introduced mixed gas is 0.86 L / h, the introduction period of the mixed gas is shortened to 6 hours, and the amount of oxygen gas in the introduced mixed gas is maintained at 0.5 mol. The butoxydibutylborane produced in Comparative Example 3 was found to have a purity of 92.8% by relative area analysis of gas-phase chromatography. By calculation, its yield was found to be 91.7%. See Table 1 below.

[0039] Comparative Example 4 The difference between Comparative Example 4 and Example 1 is that air was used as the gaseous raw material, the oxygen gas supply flow rate in the air was 0.86 L / h, the gas input period was shortened to 6 hours, and the amount of oxygen gas in the input air was maintained at 0.5 mol. The butoxydibutylborane produced in Comparative Example 4 was found to have a purity of 82.9% by relative area analysis of gas-phase chromatography. By calculation, its yield was found to be 89.6%. See Table 1 below.

[0040] Comparative Example 5 The difference between Comparative Example 5 and Example 1 is that air was used as the gaseous raw material, the oxygen gas supply flow rate in the air was 0.57 L / h, the gas input period was shortened to 9 hours, and the amount of oxygen gas in the input air was maintained at 0.5 mol. The butoxydibutylborane produced in Comparative Example 5 was found to have a purity of 85.3% by relative area analysis of gas-phase chromatography. By calculation, its yield was found to be 90.2%. See Table 1 below.

[0041] Comparative Example 6 The butoxydibutylborane prepared in Comparative Example 4 was subjected to vacuum distillation in a nitrogen gas atmosphere, and the fraction at 92-94°C / 8mmHg was collected. The resulting butoxydibutylborane was found to have a purity of 97.2% by relative area analysis of gas-phase chromatography. Calculations revealed a yield of 72.1%. See Table 1 below.

[0042] Comparative Example 7 Under a nitrogen gas atmosphere, 182 g of n-tributylborane was injected into the reactor. The reaction temperature was maintained below 80°C, and 74 g of anhydrous n-butyl alcohol was gradually added dropwise while stirring. The reaction was then refluxed under continued stirring and heating. After 24 hours of reflux, heating was stopped to obtain a butoxydibutylborane mixture. Relative area analysis by gas-phase chromatography revealed a purity of 94.8%, and calculations showed a yield of 94.6%. See Table 1 below.

[0043] Comparative Example 8 The butoxydibutylborane mixture prepared in Comparative Example 7 was subjected to vacuum distillation in a nitrogen gas atmosphere, and the fraction at 92-94°C / 8 mmHg was collected. The resulting butoxydibutylborane was found to have a purity of 97.6% by relative area analysis of gas-phase chromatography. Calculations revealed a yield of 85.4%. See Table 1 below.

[0044] The following describes the ignition stability test, polymerization activity test, and adhesive strength test when applied as a polymerization initiator to hard tissue adhesion, performed on the butoxydibutylborane products produced in the exemplary examples and comparative examples of the present invention.

[0045] 1. Ignition stability test Ignition stability tests were performed on the target products, butoxydibutylborane, produced in Examples 1-10 and Comparative Examples 1-8, specifically as follows:

[0046] At 23°C ± 2°C, 0.5 ml of the butoxydibutylborane prepared in each example and comparative example was dropped onto filter paper (Whatman, No. 3), and allowed to stand. The presence or absence of charring or ignition of the filter paper was observed. The results of the ignition stability are shown in Table 1.

[0047] 2. Polymerization activity test To demonstrate the applicability of butoxydibutylborane produced in this invention as a polymerization initiator for hard tissue repair adhesives, polymerization activity tests were conducted using the butoxydibutylborane produced in Examples 1 to 3, 7, 9, and 10 as examples, with polymerization activity expressed by curing time. The details of the polymerization activity test are specifically as follows.

[0048] i) In a room at 25℃±2℃, 0.18g of monomer (composition: MMA / 4-META=95 / 5, weight ratio) and 2 drops (approximately 0.015g) of polymerization initiator butoxydibutylborane were added dropwise to a glass mixing dish. Then, 0.16g of polymethacrylic acid powder (number average molecular weight 400,000, average particle size approximately 25μm) was added and the mixture was gently mixed for 10 seconds to obtain a resin slurry.

[0049] ii) A thin layer of petroleum jelly was applied to a glass plate, and a Teflon ring (outer diameter 13 mm, inner diameter 10 mm, thickness 5 mm), which had also been thinly coated with petroleum jelly, was placed on the glass plate, and resin slurry was poured in.

[0050] iii) Within 30 seconds of the start of mixing, the glass plate containing the resin slurry was transferred to a constant temperature chamber at 37±2°C and 100% humidity. A Viggor needle was then gently dropped onto the surface of the test specimen to check for needle marks. The time from the start of mixing until no needle marks were left on the test specimen was defined as the curing time.

[0051] The results of the polymerization activity test are shown in Table 1.

[0052] Furthermore, for the sake of comparison, polymerization activity tests were also performed on the butoxydibutylborane produced in Comparative Examples 6 and 8. The results are shown in Table 1.

[0053] 3. Test of adhesion strength with hard tissues (1) Under running water, the labial portion of the bovine incisor was polished with coarse emery paper to expose a flat enamel surface, and then polished with 600-grit emery paper to form the bonding surface. After drying this bonding surface, it was treated with a 35% (by weight) phosphoric acid etching solution for 10 seconds, rinsed with water for 10 seconds, and air-blown dry for 15 seconds. The bonding area was then defined by applying cellophane tape with a 4 mm diameter hole to the bonding surface.

[0054] (2) At room temperature of 25℃±2℃, 0.18 g of monomer (composition: MMA / 4-META=95 / 5, weight ratio) and 2 drops (approximately 0.015 g) of butoxydibutylborane prepared in Example 1 were added dropwise to a glass mixing dish, and then 0.16 g of polymethacrylic acid powder (number average molecular weight 400,000, average particle size approximately 25 μm) was added and the mixture was lightly mixed for 10 seconds to obtain a resin slurry.

[0055] (3) This resin slurry was applied to the bonding surface prepared in (1), and the acrylic rod was bonded to it to create a sample for bonding testing.

[0056] The adhesion test sample was left at room temperature for 30 minutes, and then immersed in 37°C distilled water for 24 hours. The adhesion strength between the acrylic rod and enamel was then measured according to the test method of ISO / TS 11405:2015 (Dental - Test of adhesion to tooth structure) (tensile speed 1.0 mm / min). The adhesion strength was calculated as the average of 5 test measurements and was 10.6 MPa.

[0057] [Table 1] TIFF2026509036000002.tif208149 TIFF2026509036000003.tif86149

[0058] As is clear from Table 1, In Comparative Examples 4 and 5, tributylborane was reacted with air alone as the gaseous raw material. The purity of the resulting butoxydibutylborane was low, at only 82.2% and 85.3%, respectively. Due to the low purity, the resulting butoxydibutylborane exhibited significant charring / ignition, and the ignition safety was not improved.

[0059] In Comparative Example 6, the low-purity butoxydibutylborane obtained in Comparative Example 4 was subjected to vacuum distillation to purify the product. As a result, the product after distillation purification had high purity, reaching 97.2%, but the vacuum distillation purification process significantly reduced the product yield to only 72.1%.

[0060] In Comparative Example 1, similar to the present invention, a mixed gas consisting of nitrogen gas and air was used as the gas raw material to react with tributylborane. However, the volume ratio of nitrogen gas to air was 0.5:1, and the purity of the butoxydibutylborane produced was only 90%, resulting in a significant charring phenomenon.

[0061] In Comparative Examples 2 and 3, tributylborane was reacted with a mixed gas in which the volume ratio of nitrogen gas to air was 0.7 and 1, respectively. However, the actual flow rate of oxygen gas introduced reached as high as 0.86 L / h, and the purity of the butoxydibutylborane produced was not very high, at 90.8% and 92.8%, respectively, resulting in a significant charring phenomenon.

[0062] As is clear from Examples 1 to 10, the purity of the butoxydibutylborane produced by the method of the present invention is 95% or higher, and no significant charring or ignition phenomena were observed in any of the samples. Furthermore, as can be seen by comparing the actual flow rates of oxygen gas introduced in Examples 1 and 2, Examples 5 and 6, and Examples 7 and 8, the butoxydibutylborane produced by reacting under a relatively gentle oxygen gas flow rate under the same nitrogen gas to air volume ratio conditions has higher purity and yield. For example, in Examples 7 and 8, the volume ratio of nitrogen gas to air is 2 / 1 in both cases, but the actual flow rate of oxygen gas introduced in Example 8 was relatively gentle (0.43 L / h), and the purity of the butoxydibutylborane produced under these conditions was high at 97.6%, and the yield was also high at 94.4%.

[0063] As described above, the manufacturing method of the present invention makes it possible to obtain butoxydibutylborane with high purity and improved flammability.

[0064] Although the present invention has been specifically described above by combining exemplary embodiments, these embodiments are merely illustrative and cannot limit the scope of protection of the present invention. Those skilled in the art can make various modifications, changes, or substitutions to the present invention, provided they do not deviate significantly from its substance and scope. Therefore, various equivalent changes made based on the present invention remain within the scope of protection of the present invention.

Claims

1. The process includes a step of introducing a gaseous raw material containing oxygen gas into a reaction vessel containing a liquid n-tributylborane raw material, and oxidizing the n-tributylborane to produce butoxydibutylborane. The aforementioned gas raw material is a mixture of an inert gas and air. The volume ratio of the inert gas to air is 0.7 or greater. A method for producing butoxydibutylborane, wherein the supply flow rate of oxygen gas in the mixed gas is 0.86 L / h or less per 1 mol of n-tributylborane raw material.

2. The method according to claim 1, wherein the volume ratio of the inert gas to air is 0.7 to 2.

3. The method according to claim 2, wherein the volume ratio of the inert gas to air is 1 to 2.

4. The method according to any one of claims 1 to 3, wherein the molar ratio of oxygen gas to n-tributylborane contained in the introduced mixed gas is 0.44 to 0.

6.

5. The method according to claim 4, wherein the supply flow rate of oxygen gas in the mixed gas is 0.43 L / h to 0.57 L / h per 1 mol of n-tributylborane raw material.

6. The method according to claim 1, wherein the inert gas is selected from nitrogen gas, helium gas, neon gas, and argon gas.

7. The method according to claim 1, wherein the purity of the butoxydibutylborane produced by the oxidation reaction of n-tributylborane is 95% or higher.

8. The method according to claim 1, wherein the temperature of the reactant n-tributylborane is 15°C to 80°C.

9. Butoxydibutylborane produced by the method described in any one of claims 1 to 8.

10. Use of the butoxydibutylborane described in claim 9 as a polymerization initiator for hard tissue repair adhesives.

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