Continuous flow synthesis method of electronic-grade methylsilane

Abstract

The invention relates to the technical field of preparation of electronic chemicals, and provides a continuous flow synthesis method of electronic-grade methylsilane, which is characterized in that magnesium chips, halogenated hydrocarbon and chlorosilane are used as raw materials, and a Grignard reactor and a tubular reactor are utilized to continuously produce the electronic-grade methylsilane. The preparation method is simple to operate and high in product purity, and meanwhile, the intrinsic safety of the process is improved. After the Grignard reagent is obtained through the reaction, the alkylation reaction is directly carried out, the danger of the Grignard reagent in the separation, transportation and feeding process is avoided, meanwhile, the tubular reactor is adopted in the alkylation reaction, the reaction safety is improved, and meanwhile the reaction selectivity is improved.

Description

Technical Field

[0001] This invention relates to the field of electronic chemical preparation technology, and in particular to a continuous flow synthesis method for electronic-grade methylsilane. Background Technology

[0002] Methylsilanes are important organosilicon materials with wide applications in pharmaceuticals, aerospace, construction, and machinery. Ultra-high purity methylsilanes are used in the semiconductor and integrated circuit industries as precursors for chemical vapor deposition (CVD), such as plasma-enhanced chemical vapor deposition (PECVD) and atomic layer deposition (ALD), to prepare high-quality thin films and low-k materials. Currently, the main products in demand in the electronic-grade methylsilane market are tetramethylsilane (4MS) and trimethylsilane (3MS).

[0003] Currently, the synthesis of 4MS and 3MS is based on the alkylation batch process using Grignard reagents, which carries risks related to the generation, separation, transportation, and feeding of Grignard reagents. Furthermore, alkylation is one of the eighteen key regulated hazardous processes, requiring high standards for reaction conditions, equipment, and process control.

[0004] Microreactors, due to their strong heat exchange and mass transfer characteristics, are widely used in various organic reactions, especially highly exothermic and hazardous reactions. They not only allow for precise control of reaction temperature, shorten reaction time, and improve reaction selectivity, but also reduce reactor volume without decreasing yield. Furthermore, because the liquid hold-up volume within the reactor per unit time is significantly smaller than that of conventional reactors, the inherent safety of the process is enhanced. Therefore, a continuous flow synthesis method is needed to synthesize electronic-grade methylsilanes. Summary of the Invention

[0005] In view of this, the purpose of this invention is to provide a continuous flow synthesis method for electronic-grade methylsilanes, which solves the problems in the prior art.

[0006] To achieve the above objectives, the present invention provides a continuous flow synthesis method for electronic-grade methylsilanes, comprising the following steps: Step 1: Magnesium shavings are added to the Grignard reactor, and an organic solvent and a halogenated hydrocarbon are introduced using a plunger pump to obtain a methyl magnesium chloride solution; Step 2: A solution of methyl magnesium chloride and chlorosilane is introduced into the tubular reactor using a plunger pump, and the reaction product methyl silane solution is obtained. Step 3: The obtained methylsilane solution is distilled and purified to obtain electronic-grade methylsilane with a purity of 6N. The general chemical formula of methylsilane is Si(CH3). x H 4-x , where X = 1 - 4.

[0007] Preferably, the halogenated hydrocarbon in step one is one of chloromethane, bromomethane, and iodomethane.

[0008] Preferably, the organic solvent in step one is an ether-based organic solvent, which is one of tetrahydrofuran, 2-methyltetrahydrofuran, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, and diethylene glycol dimethyl ether.

[0009] Preferably, the ether solvent is 2-methyltetrahydrofuran or ethylene glycol dimethyl ether.

[0010] Preferably, the reaction temperature of the Grignard reaction in step one is -20 to 60°C, the molar ratio of magnesium shavings to haloalkanes is in the range of 100:1 to 10:1, the mass ratio of haloalkanes to organic solvent is in the range of 1:5 to 1:20, the concentration of the obtained methyl magnesium chloride is in the range of 1 to 3M, and the liquid holding time is in the range of 10 to 120 minutes.

[0011] Preferably, the reaction temperature of the tubular reaction in step two is -20 to 60°C, the molar ratio of methylmagnesium chloride to chlorosilane is 5:1 to 1:1, and the liquid holding time is 10 to 120 minutes.

[0012] Preferably, the dichlorosilane in the step has the common chemical formula Si(CH3). m Cl n H 4-n-m , where m=0-3, n=1-4, m+n=1-4.

[0013] Preferably, the chlorosilane is one of trimethylchlorosilane, dimethylmonochlorosilane, trichlorosilane, and tetrachlorosilane.

[0014] Preferably, the synthesis method is carried out at room temperature under nitrogen protection.

[0015] The beneficial effects of this invention are as follows: The continuous flow synthesis method employed in this invention uses magnesium shavings, halogenated hydrocarbons, and chlorosilanes as raw materials, and utilizes a Grignard reactor and a tubular reactor to continuously produce electronic-grade methylsilanes. The preparation method is simple to operate, produces high-purity products, and improves the inherent safety of the process. After obtaining the Grignard reagent, the alkylation reaction is directly carried out, avoiding the dangers associated with the separation, transportation, and feeding of the Grignard reagent. Furthermore, the use of a tubular reactor for the alkylation reaction not only improves reaction safety but also enhances reaction selectivity.

[0016] The modular continuous flow design, combining a Grignard reactor and a tubular reactor, offers advantages over traditional batch reactions: continuous material delivery and reaction eliminate downtime and waiting during intermittent operation, resulting in higher output per unit time. Precise control of feed rate, holding time (10~120 minutes), and temperature (-20~60℃) via a plunger pump ensures excellent reaction parameter uniformity and minimal batch-to-batch product variation. Continuous flow equipment is easily scaled up, making it suitable for large-scale production of electronic-grade materials.

[0017] A two-step purification process involving distillation and rectification removes solvents, unreacted raw materials, and trace byproducts, ultimately yielding a 6N (99.9999%) purity product, fully meeting the stringent impurity content requirements of semiconductor chip CVD processes; covering Si(CH3). x H4₋ x (x=1~4) A full range of products to meet the needs of different electronic material scenarios.

[0018] High-performance ether solvents such as 2-methyltetrahydrofuran / ethylene glycol dimethyl ether are used to improve the stability of the Grignard reagent, namely methyl magnesium chloride, and reduce polymerization side reactions. The diverse selection of halogenated hydrocarbons and chlorosilanes allows for precise control of the degree of substitution of the target product, making it suitable for different application scenarios.

[0019] The molar ratio of magnesium shavings to halogenated hydrocarbons (100:1~10:1) ensures complete conversion of raw materials, and the concentration of methyl magnesium chloride (1~3M) balances reaction activity and stability; by-products such as magnesium chloride salts can be easily separated and recovered, improving resource utilization and simplifying subsequent environmental treatment processes.

[0020] In summary, this solution combines high efficiency, stability, high purity, flexibility, and environmental safety, making it the preferred process for the industrial production of electronic-grade methylsilane. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only for this invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a GC-MS detection image of electronic-grade tetramethylsilane from Example 1. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0024] It should be noted that, unless otherwise defined, the technical or scientific terms used in this invention should have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly. Example

[0025] This embodiment provides a continuous flow synthesis method for electronic-grade tetramethylsilane, comprising the following steps: S1. Under nitrogen protection at room temperature, 200g of magnesium shavings with a liquid holdup of 1L are added into the Grignard reactor through the solid feed port at the top of the Grignard reactor. 200ml of 2-methyltetrahydrofuran and 20g of chloromethane gas are introduced using a plunger pump. The feed rates of 2-methyltetrahydrofuran are set to 50mL / min and chloromethane to 5g / min. The mixture is premixed by cooling to -10℃ through a premixing module. The Grignard reaction is carried out to obtain a methyl magnesium chloride solution, which is maintained at 30-40℃. S2. Under room temperature and nitrogen protection conditions, after the initial material inside the Grignard reactor is discharged and the stable discharge is detected, it enters the Grignard reagent temporary storage tank. S3. At room temperature and under nitrogen protection, methyl magnesium chloride solution and trimethylchlorosilane are introduced into a tubular reactor. The feed rates of methyl magnesium chloride solution are set to 36 g / min and trimethylchlorosilane to 4 g / min. The tubular reaction is carried out to obtain tetramethylsilane. After the initial material is discharged from the tubular reactor and the stable discharge is detected, the product is sent to the product storage tank. S4. Tetramethylsilane is passed into a distillation kettle, and the temperature is controlled at 40°C for discharge. The temperature is gradually increased to 60°C, and the fraction is collected. The fraction is crude tetramethylsilane with a yield of 85%. S5. The crude tetramethylsilane is subjected to atmospheric distillation. The fore fraction is removed at 5-10 wt% of the tetramethylsilane content, and the hind fraction is removed at 15-20 wt% of the tetramethylsilane content to obtain the middle fraction, which is electronic grade tetramethylsilane.

[0026] The electronic-grade tetramethylsilane was detected using inductively coupled plasma atomic emission spectrometry (ICP-AES), as shown in Table 1. Table 1. ICP-MS detection results of tetramethylsilane Tetramethylsilane was detected using GC-MS electronic grade, and the test results are as follows: Figure 1 The final distillate obtained is tetramethylsilane, and all inorganic elements in tetramethylsilane are <1ppm, with a purity of 6N.

[0027] Example 2 This embodiment discloses a synthetic route for electronically graded trimethylsilane, including the following steps: S1. Under nitrogen protection at room temperature, 200g of magnesium shavings with a liquid holdup of 1L are added into the Grignard reactor through the solid feed port at the top of the Grignard reactor. 200ml of ethylene glycol dimethyl ether and 40g of bromomethane gas are introduced using a plunger pump. The feed rates of ethylene glycol dimethyl ether are set to 50mL / min and bromomethane to 10g / min. The mixture is premixed by cooling to -10℃ through a premixing module. The Grignard reaction is carried out to obtain a methyl magnesium chloride solution, which is maintained at 30-40℃. S2. Under room temperature and nitrogen protection conditions, after the initial material inside the Grignard reactor is discharged and the stable discharge is detected, it enters the Grignard reagent temporary storage tank. S3. At room temperature and under nitrogen protection, methyl magnesium chloride solution and trichlorosilane are introduced into a tubular reactor. The feed rates of methyl magnesium chloride solution are set to 40 g / min and trichlorosilane to 2 g / min. The tubular reaction is carried out to obtain trimethylsilane. After the tubular reactor stabilizes and discharges, the product is transferred to the product storage tank.

[0028] S4. Trimethylsilane is introduced into the distillation vessel, and the pressure of the distillation vessel is controlled at 300 kPa and the temperature at 30°C. Stir for 6 hours. After stirring, the pressure is restored to normal pressure to distill off the trimethylsilane and collect it in the crude product receiving tank. Finally, it is transferred to the bottom of the distillation vessel. S5. Distillation is carried out at a pressure of 200 kPa and a temperature of 25-30°C in the bottom distillation vessel. Light components are removed at a ratio of 5%, and the fraction at around 25°C is collected in the product tank, which is the trimethylsilane product. The trimethylsilane was detected using inductively coupled plasma atomic emission spectrometry (ICP-AES), as shown in Table 2. The test results show that the final prepared middle fraction is trimethylsilane, and all inorganic elements in the trimethylsilane are <1 ppm, with a purity of 6N.

[0029] Table 2. ICP-MS detection results of trimethylsilane Examples 1 and 2 demonstrate that the electronic-grade trimethylsilane and tetramethylsilane obtained using the synthesis method of this invention can achieve a content of 99.9999%. The preparation method is simple to operate, produces high-purity products, and simultaneously improves the inherent safety of the process.

[0030] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention is limited to these examples; within the framework of the invention, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and many other variations of different aspects of the invention as described above exist, which are not provided in detail for the sake of brevity. Any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the invention should be included within the scope of protection of the invention.

Claims

1. A continuous flow synthesis method for electronic-grade methylsilanes, characterized in that, Includes the following steps: Step 1: Magnesium shavings are added to the Grignard reactor, and an organic solvent and a halogenated hydrocarbon are introduced using a plunger pump to obtain a methyl magnesium chloride solution; Step 2: A solution of methyl magnesium chloride and chlorosilane is introduced into the tubular reactor using a plunger pump, and the reaction product methyl silane solution is obtained. Step 3: The obtained methylsilane solution is distilled and purified to obtain electronic-grade methylsilane with a purity of 6N. The general chemical formula of methylsilane is Si(CH3). x H 4-x , where X = 1 - 4.

2. The continuous flow synthesis method for electronic-grade methylsilane according to claim 1, characterized in that, The halogenated hydrocarbon in step one is one of chloromethane, bromomethane, and iodomethane.

3. The continuous flow synthesis method for electronic-grade methylsilane according to claim 1, characterized in that, The organic solvent in step one is an ether-based organic solvent, which is one of tetrahydrofuran, 2-methyltetrahydrofuran, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, and diethylene glycol dimethyl ether.

4. The continuous flow synthesis method for electronic-grade methylsilane according to claim 3, characterized in that, The ether-based organic solvent is 2-methyltetrahydrofuran or ethylene glycol dimethyl ether.

5. The continuous flow synthesis method for electronic-grade methylsilane according to claim 1, characterized in that, The reaction temperature of the Grignard reaction in step one is -20 to 60°C, the molar ratio of magnesium shavings to haloalkanes is 100:1 to 10:1, the mass ratio of haloalkanes to organic solvent is 1:5 to 1:20, the concentration of the obtained methylmagnesium chloride is 1 to 3M, and the liquid holding time is 10 to 120 minutes.

6. The continuous flow synthesis method for electronic-grade methylsilane according to claim 1, characterized in that, The reaction temperature of the tubular reaction in step two is -20 to 60°C, the molar ratio of methylmagnesium chloride to chlorosilane is 5:1 to 1:1, and the liquid holding time is 10 to 120 minutes.

7. The continuous flow synthesis method for electronic-grade methylsilane according to claim 6, characterized in that, The dichlorosilane mentioned in the step has the general chemical formula Si(CH3). m Cl n H 4-n-m , where m=0-3, n=1-4, m+n=1-4.

8. The continuous flow synthesis method for electronic-grade methylsilane according to claim 7, characterized in that, The chlorosilane is one of trimethylchlorosilane, dimethylmonochlorosilane, trichlorosilane, and tetrachlorosilane.

9. The continuous flow synthesis method for electronic-grade methylsilane according to claim 1, characterized in that, The synthesis method is carried out at room temperature under nitrogen protection.

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