Preparation method and device of trimethyl boron
By using trimethylaluminum to react with boron trichloride and combining it with a continuous production device, the problem of separating by-products in the preparation of trimethylboron was solved, the yield and purity were improved, the cost was reduced, and the process was simplified.
Patent Information
- Application Number
- CN202511281847.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-09
- Publication Date
- 2025-10-17
AI Technical Summary
In the existing method for preparing trimethylborane, the generated by-product B(CH3)2(C2H5) is difficult to separate, the cost of the Grignard reagent is high, the reaction process is complicated, and the yield and purity are low.
The method uses trimethylaluminum produced on a large scale as a methylating agent to react with boron trichloride. Trimethylboron is prepared through a continuous production reaction device, including a feeding system, a reaction system, a product purification system and a temperature control system. The reaction conditions are controlled to obtain high-purity trimethylboron.
The conversion rate of boron trichloride reached 99%, the yield of trimethylboron reached 95%, and the purity was >99%, which reduced costs and simplified the process.
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Figure CN120795010A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the field of fine chemicals, in particular to a preparation method and device of trimethylboron. BACKGROUND
[0002] Trimethylboron (B(CH3)3) is a volatile organoboron compound with important application value. As the simplest trialkylborane, it plays a key role in multiple high-tech fields. In the field of organic synthesis, trimethylboron, due to its strong Lewis acidity, is an important catalyst that can effectively promote borohydration, olefin polymerization and other organic conversion reactions, and has unique advantages in the synthesis of drug intermediates and special materials. In the semiconductor manufacturing industry, trimethylboron, with its suitable vapor pressure and thermal stability, is widely used as a p-type doping source in chemical vapor deposition (CVD) and atomic layer deposition (ALD) processes, which is essential for the preparation of high-performance electronic devices. In addition, trimethylboron has also been studied as a high-energy fuel additive, and its high combustion heat value makes it have potential application value in the field of aerospace.
[0003] Currently, the preparation of trimethylboron mainly uses Grignard reagent method, and the reaction equation is shown below. High-purity magnesium chips are immersed in a dehydrated n-butyl ether solution, and a certain amount of pure bromomethane n-butyl ether solution is added dropwise. The reaction forms the raw material Grignard reagent. Purified boron trifluoride gas is directly introduced into the ether solution of CH3MgBr, and trimethylboron is generated by reaction. The crude trimethylboron prepared is pretreated, and BF3 and other impurities are removed by rectification to obtain trimethylboron with higher purity.
[0004]
[0005] The main difficulty of this reaction is that in the second step, CH3MgBr or CH3MgCl is very active, and in the reaction with boron trifluoride, not only trimethylboron is generated, but also B(CH3)2(C2H5) is generated, which is difficult to separate. In addition, the cost of Grignard reagent is also relatively high, and the reaction involves gas-liquid-solid three-phase reaction, which is complex.
[0006] The present application provides a new method for efficiently preparing trimethylboron, which uses scale production of trimethylaluminum as a methylation reagent and boron halide as a raw material. The cost of the raw material is greatly reduced, the economy is good, the yield is high, and there is no by-product of ethyl-substituted boron species. The conversion rate of boron trichloride is 99%, the yield of trimethylboron is 95%, and the purity is >99%. A reaction device for preparing trimethylboron by the above method is also provided. SUMMARY
[0007] In view of the problems of the by-product B(CH3)2(C2H5) generated in the preparation of trimethyl boron by using the existing format reagent method, the difficulty in separation, the high cost of the format reagent and the complex reaction process, the present application provides a new method for preparing trimethyl boron, which uses large-scale production of trimethyl aluminum as a methylating agent and boron halide as a raw material, the conversion rate of boron trichloride is 99%, and the yield of trimethyl boron is up to 95%, and a set of reaction device for preparing trimethyl boron by the above method is also provided.
[0008] The preparation method of trimethyl aluminum according to the present application has the following specific process route:
[0009] A trimethyl boron preparation method, under anhydrous and anaerobic conditions, trimethyl aluminum reacts with boron trichloride to prepare trimethyl boron, the reaction temperature is 0-30℃, the generated trimethyl boron is gasified from the reaction system, and after purification, it is collected by condensation, and the purity of the obtained product is >99%.
[0010] Further, the trimethyl aluminum is used as a reaction raw material alone without an organic solvent, or the trimethyl aluminum is configured into a solution with an organic solvent, and the mass fraction of the trimethyl aluminum in the solution is 20-100%.
[0011] Further, the solvent is an alkane C n H 2n+2 , a cycloalkane or an aromatic compound, and n≥6.
[0012] Further, the molar ratio of the total amount of boron trichloride to trimethyl aluminum is 1:1.1-3.0.
[0013] Further, the mass fraction of the trimethyl aluminum in the solution is 40-50%, the molar ratio of the total amount of boron trichloride to trimethyl aluminum is 1:1.2-1.6, and the solvent is hexane, heptane, octane, nonane, decane, dodecane or tetrahydronaphthalene.
[0014] A device for a trimethyl boron preparation method, which adopts a continuous production reaction device composed of a feeding system, a reaction system, a product purification system, a product collection system and a temperature control system, and can efficiently produce trimethyl boron with a purity of >99%, or a conventional batch kettle type reactor is used to produce trimethyl boron.
[0015] Further, in the continuous production reaction device, the trimethylaluminum metering feeding in the feeding system uses a trimethylaluminum steel bottle with a plug-in bottom pipe, trimethylaluminum is pressed into the reaction system through pumping or inert gas pressure control, and the addition amount is metered through a weight loss method or a mass flow meter; the boron trichloride gas is metered into the reaction system through a mass flow meter by connecting a polytetrafluoroethylene pipeline with a boron trichloride steel bottle. The reaction system is a reaction kettle with a jacket temperature control or a coil temperature control, and the reaction kettle is provided with a stirrer and a thermometer. The reaction kettle is one or more, and multiple reaction kettles are connected through a glass sleeve. The reaction liquid overflows into the next reaction kettle through the glass sleeve, so that the yield and residence time can be improved. The product purification system is matched on the last reaction kettle of the reaction system, and is provided with a glass rectifying column, including a jacket type rectifying column, a rectifying head, a condenser, a reflux ratio controller and a receiving bottle. The product collection system is used for collecting the purified trimethylboron into a stainless steel steel bottle with an inert gas protection device and a plug-in bottom pipe. The product collection system is also provided with a low-temperature cold bath circulation device for liquefying trimethylboron. The temperature control system precisely controls the temperature of the reaction kettle, the jacket type rectifying column, the condenser and the low-temperature cold bath circulation device, respectively.
[0016] Further, the temperature of the jacket type rectifying column is controlled at 2-7℃, the temperature of the condenser is controlled at -20--30℃, and the temperature of the low-temperature cold bath circulation device in the product collection system is controlled at <-25℃.
[0017] The beneficial effects of the present application are as follows:
[0018] (1) The method uses large-scale production trimethylaluminum as a methylation reagent, which has lower cost than the existing format reagent method, and the format reagent method is divided into two steps of reaction, involves gas-liquid-solid three phases, and has a more complex process, while the process using trimethylaluminum is simpler;
[0019] (2) Trimethylaluminum is used as a methylation reagent, the yield of trimethylboron is 95%, and the purity is >99%, which is higher than that of the format reagent method;
[0020] (3) A set of reaction device for continuously preparing trimethylboron is provided, which can effectively promote the conversion of boron trichloride. BRIEF DESCRIPTION OF DRAWINGS
[0021] Figure 1 The nuclear magnetic structure spectrum of trimethylboron is shown in the figure 11 B NMR (128 MHz);
[0022] Figure 2 The device for preparing trimethylboron is shown in the figure
[0023] 1 - Trimethylaluminum cylinder, 2 - Boron trichloride cylinder, 3 - Balance, 4 - Mass flow meter, 5 - Glass jacketed reactor 1, 6 - Glass jacketed reactor 2, 7 - Rectification head, 8 - Condenser, 9 - Reflux ratio controller, 10 - Receiving cylinder, 11 - Rectification column, 12 - Boron trimethyl cylinder, 13 - Cryogenic cooling bath circulation equipment. DETAILED DESCRIPTION
[0024] In order to make the person skilled in the art better understand the present application, the present application is further illustrated by the following examples, but these examples cannot limit the scope of the present application, and the technical means used in the examples are the conventional means known to those skilled in the art.
[0025] In the present application, unless otherwise specified, the experimental methods used are conventional methods, and the materials, reagents, etc. used can be purchased from commercial channels.
[0026] Example 1
[0027] Under anhydrous and anaerobic conditions, trimethylaluminum (6.92 g, 96 mmol) was first added to a glass reaction bottle, and under the condition of 20°C, boron trichloride (7.03 g, 60 mmol) was continuously introduced into the reaction bottle. During the feeding process, the continuous vaporization of trimethylboron was accompanied, and after the purification system of the vaporized trimethylboron was purified, the pure trimethylboron was finally condensed and received. The conversion rate of boron trichloride was 99%, the yield of trimethylboron was 95%, and the purity of the product was > 99%.
[0028] Example 2
[0029] Under anhydrous and anaerobic conditions, 17.3 g of 40 wt% trimethylaluminum n-hexane solution (containing trimethylaluminum 6.92 g, 96 mmol) was first added to a glass reaction bottle, and under the condition of 20°C, boron trichloride (7.03 g, 60 mmol) was continuously introduced into the reaction bottle. During the feeding process, the continuous vaporization of trimethylboron was accompanied, and after the purification system of the vaporized trimethylboron was purified, the pure trimethylboron was finally condensed and received. The conversion rate of boron trichloride was 99%, the yield of trimethylboron was 94%, and the purity of the product was > 99%.
[0030] Example 3
[0031] Under the condition of no water and no oxygen, first, 11.5 g of 60 wt% trimethylaluminum n-decane solution (containing trimethylaluminum 6.92 g, 96 mmol) was added to a glass reaction bottle, and at 20°C, boron trichloride (7.03 g, 60 mmol) was continuously introduced into the reaction bottle. During the feeding process, trimethylboron was continuously gasified. After the purified system of the gasified trimethylboron was purified, pure trimethylboron was finally condensed and received. The conversion rate of boron trichloride was 99%, the yield of trimethylboron was 94%, and the product purity was >99%.
[0032] Example 4
[0033] Under the condition of no water and no oxygen, first, 17.3 g of 40 wt% trimethylaluminum decaline solution (containing trimethylaluminum 6.92 g, 96 mmol) was added to a glass reaction bottle, and at 20°C, boron trichloride (7.03 g, 60 mmol) was continuously introduced into the reaction bottle. During the feeding process, trimethylboron was continuously gasified. After the purified system of the gasified trimethylboron was purified, pure trimethylboron was finally condensed and received. The conversion rate of boron trichloride was 99%, the yield of trimethylboron was 93%, and the product purity was >99%.
[0034] Examples 5-15
[0035] As shown in the following table, by adjusting the molar ratio of trimethylaluminum to boron chloride and the reaction temperature, the yield of trimethylboron was investigated. A 50 wt% trimethylaluminum hexane solution was used, and the remaining process parameters were the same as those in Example 1.
[0036]
[0037] Example 16 scale-up
[0038] This example was carried out in a reaction device built as shown in Figure 2 The reaction device was composed of a feeding system, a reaction system, a product purification system, a product collection system, and a temperature control system.
[0039] The feeding system of the device uses a trimethylaluminum steel cylinder with a plug-in bottom tube to measure the feeding of trimethylaluminum. Nitrogen is introduced into the gas passage of the trimethylaluminum steel cylinder to bring liquid trimethylaluminum into the reaction system. Trimethylaluminum is added to the reaction kettle by the gravimetric method. Boron trichloride gas is measured by a mass flow meter and continuously added to the reaction system through a polytetrafluoro tube connected to the boron trichloride steel cylinder. The reaction system is two 500 mL jacketed temperature-controlled reaction kettles equipped with stirrers and thermometers. The product purification system is equipped on the last reaction kettle of the reaction system and is equipped with a glass rectification column, including a jacketed rectification column, a rectification head, a condenser, a reflux ratio controller, and a receiving bottle (the rectification column is connected to the last reaction kettle, the top is connected to the rectification head, the rectification head is connected to the condenser, the condenser is provided with a reflux ratio controller, and the condenser is connected to the receiving bottle). The product collection system is a stainless steel cylinder with inert gas protection device and plug-in bottom tube. The product collection system is also equipped with a low-temperature cold bath circulation device for liquefying trimethylboron. The temperature control system precisely controls the temperature of the reaction kettle, the jacketed rectification column, the condenser, and the low-temperature cold bath circulation device. In this embodiment, the temperature of the jacketed rectification column is controlled at 5°C, the temperature of the condenser is controlled at -25°C, and the temperature of the low-temperature cold bath circulation device of the product collection system is controlled at -40°C.
[0040] Under anhydrous and anaerobic conditions, trimethylaluminum (450 g, 6.24 mol) is first added to a 500 mL jacketed glass reaction kettle by the gravimetric method, and the temperature is controlled at 30°C. Then, boron trichloride (total 610 g, 5.2 mol) is continuously introduced into the reaction bottle through a mass flow meter. During the feeding process, the continuously vaporized trimethylboron is purified through the purification system, and finally condensed and received to obtain pure trimethylboron. The yield of trimethylboron is 95%, and the purity is >99%.
[0041] The above is only a preferred specific embodiment of the present application, but the protection scope of the present application is not limited thereto. Those skilled in the art can easily think of changes or replacements within the technical scope disclosed in the present application, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.
Claims
1. A method for preparing trimethylboron, characterized in that: Under anhydrous and oxygen-free conditions, trimethylaluminum reacts with boron trichloride to prepare trimethylboron at a reaction temperature of 0-30°C. The generated trimethylboron is vaporized from the reaction system, purified, and then condensed and collected. The purity of the obtained product is >99%.
2. The method for preparing trimethylboron according to claim 1, wherein: The trimethylaluminum is used alone as a reaction raw material without an organic solvent; or the trimethylaluminum is configured with an organic solvent to form a solution, wherein the mass fraction of the trimethylaluminum in the solution is 20-100%.
3. A method for preparing trimethylboron according to claim 2, characterized in that, The solvent is an alkane C n H 2n+2 , cycloalkane or aromatic compounds, n≥6.
4. A method for preparing trimethylboron according to claim 1, 2 or 3, characterized in that: The molar ratio of the total amount of boron trichloride to trimethylaluminum is 1:1.1-3.
0.
5. A method for preparing trimethylboron according to claim 2 or 3, characterized in that, The mass fraction of trimethylaluminum in the solution is 40-50%; the molar ratio of the total amount of boron trichloride to trimethylaluminum is 1:1.2-1.6; and the solvent is hexane, heptane, octane, nonane, decane, dodecane, tetralin or decalin.
6. A device for implementing the method for preparing trimethylboron according to any one of claims 1 to 5, characterized in that: A continuous production reaction device is used, consisting of a feeding system, a reaction system, a product purification system, a product collection system and a temperature control system. The reaction device can efficiently produce trimethylboron with a purity of >99%; alternatively, a conventional batch reactor is used to produce trimethylboron.
7. A trimethylboron preparation device according to claim 6, characterized in that: In the continuous production reaction device, trimethylaluminum is metered into the feeding system using a trimethylaluminum cylinder with a bottom tube, and trimethylaluminum is pressed into the reaction system by pumping or inert gas pressure control, and the added amount is measured by weight loss method or mass flow meter; boron trichloride gas is metered into the reaction system through a mass flow meter by connecting the boron trichloride cylinder to a polytetrafluoroethylene pipeline; the reaction system is a reactor with jacket temperature control or coil temperature control, the reactor is equipped with a stirrer and a thermometer, there are one or more reactors, and the multiple reactors are connected by glass sleeves, and the reaction liquid is passed through the glass sleeves. The overflow from the tube enters the next reactor, which can increase the yield and retention time; the product purification system is equipped on the last reactor of the reaction system and is equipped with a glass distillation tower, including a jacketed distillation column, a distillation head, a condenser, a reflux ratio controller and a receiving bottle; the product collection system is to pass the purified trimethylboron into a stainless steel cylinder with an inert gas protection device and a bottom tube. The product collection system is also equipped with a low-temperature cold bath circulation equipment for liquefying trimethylboron; the temperature control system accurately controls the temperature of the reactor, jacketed distillation column, condenser and low-temperature cold bath circulation equipment respectively.
8. The trimethylboron preparation device according to claim 7, wherein the temperature of the jacketed distillation column is controlled at 2-7°C, the temperature of the condenser is controlled at -20-30°C, and the temperature of the low-temperature cold bath circulation equipment in the product collection system is controlled at less than -25°C.