Preparation method of trimethylsilane

Abstract

The invention relates to a preparation method of trimethylsilane, and relates to the technical field of chemical engineering. The method specifically comprises the following steps: S1, carrying out water removal pretreatment on a reaction solvent tetrahydrofuran; s2, respectively preparing a reducing agent solution, a catalyst suspension and a trimethylchlorosilane solution by using the tetrahydrofuran subjected to dehydration pretreatment; s3, synthesis of trimethylsilane: dropwise adding a reducing agent solution and a catalyst suspension into a trimethylchlorosilane solution to construct a liquid-liquid-solid reaction system; adjusting the pressure of the reaction system to a micro-positive pressure state, stirring in the whole process at the temperature of 20-40 DEG C, and carrying out hydrogenation reduction reaction for 1-3 hours; and S4, product collection: collecting generated gas in the reaction process, and carrying out purification treatment to obtain trimethylsilane. The method provided by the invention can effectively reduce the use proportion of a common catalyst, and has the advantages of short reaction time, high yield and cost reduction.

Description

Technical Field

[0001] This invention relates to the field of trimethylsilane synthesis technology, and more specifically to a method for preparing trimethylsilane. Background Technology

[0002] Trimethylsilane (3MS) is an organosilicon compound with the chemical formula (CH3)3SiH. It is a colorless, volatile gas. Although it possesses certain toxicity and hazards, it is widely used in semiconductor manufacturing, chemical synthesis, surface treatment, coatings and inks, and pharmaceuticals. With the rapid development of the semiconductor industry, the market demand for trimethylsilane continues to grow. According to market research reports, its market size will further expand in the coming years.

[0003] Currently, hydrogenation reduction is the mainstream technology for preparing trimethylsilane. This method involves the reaction of hydrogen atoms in the reducing agent with chlorine atoms in trimethylchlorosilane to generate the target product and hydrogen chloride byproduct, offering advantages such as high product purity and good environmental friendliness. However, existing hydrogenation reduction methods have several drawbacks: First, the large amount of reducing agent used leads to high costs. For example, invention patent CN100516074C uses lithium aluminum hydride as a strong reducing agent, resulting in excessive usage and economic burden. Second, the reaction efficiency is low and time-consuming; traditional reactions require 10-15 hours to complete, severely restricting production efficiency. Third, the yield is low, generally only 70%-80%, resulting in significant raw material waste. Fourth, some catalytic systems use expensive catalysts such as iridium-amide complexes, which, while improving reaction efficiency, are too costly and hinder industrial application. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a method for preparing trimethylsilane, which achieves efficient and low-cost synthesis through the synergistic effect of transition metal catalysis and liquid-solid multiphase reaction, combined with micro-positive pressure control.

[0005] The technical solution of this invention: A method for preparing trimethylsilane includes the following steps: S1. The reaction solvent tetrahydrofuran is pretreated to remove water; S2. Using the dehydrated pretreated tetrahydrofuran, a reducing agent solution, a catalyst suspension, and a trimethylchlorosilane solution were prepared respectively. S3. Synthesis of trimethylsilane: A reducing agent solution and a catalyst suspension are added dropwise to a trimethylchlorosilane solution to construct a liquid-liquid-solid reaction system; the pressure of the reaction system is adjusted to a slightly positive pressure, and the system is stirred throughout the process at a temperature of 20-40℃ for 1-3 hours for hydrogenation reduction reaction. S4. Product collection: Collect the gases generated during the reaction.

[0006] Preferably, the specific steps of step S1 are as follows: add a dehydrating agent to tetrahydrofuran, stir for 6-8 hours, filter, and obtain pretreated tetrahydrofuran with a water content ≤100ppm; The dehydrating agent is one or more of anhydrous calcium chloride, molecular sieve and anhydrous magnesium chloride, mixed in any proportion; The water-removing agent has a mass percentage of 1-5%, or the solid-liquid mass ratio of the water-removing agent to tetrahydrofuran is 1-5:95-99.

[0007] Preferably, the preparation process of the reducing agent solution in step S2 is as follows: under nitrogen protection, weigh the reducing agent and add it to the reaction flask, add the dehydrated and pretreated tetrahydrofuran, and stir until completely dissolved; the mass percentage of the reducing agent in the reducing agent solution is 5%-15%; The reducing agent is one or a mixture of lithium aluminum hydride, sodium borohydride, and lithium hydride.

[0008] Preferably, the preparation process of the catalyst suspension in step S2 is as follows: weigh the transition metal catalyst, add tetrahydrofuran after dehydration pretreatment, and stir to form a suspension; The transition metal catalyst is one or more of Pt, Ni, and Cu catalysts; The mass percentage of transition metal catalyst in the catalyst suspension is 5-15%.

[0009] Preferably, the preparation process of the trimethylchlorosilane solution in step S2 is as follows: weigh trimethylchlorosilane and completely dissolve it in tetrahydrofuran after dehydration pretreatment. The volume ratio of tetrahydrofuran after dehydration pretreatment to trimethylchlorosilane is 1:1-1.3:1.

[0010] Preferably, the amount of transition metal catalyst used in step S3 is 0.5%-3% of the molar amount of trimethylchlorosilane; the molar ratio of trimethylchlorosilane to reducing agent is 1:(0.3-0.8).

[0011] Preferably, in step S3, the dropping rate of the reducing agent solution is 3d / s-1d / 5s; and the dropping rate of the catalyst suspension is 1d / s-10d / s.

[0012] Preferably, in step S3, the dropping rate of the reducing agent solution is 3 d / s; and the dropping rate of the catalyst suspension is 1 d / s.

[0013] Preferably, the stirring speed in step S3 is 100-200 r / min.

[0014] Preferably, the pressure in the slightly positive pressure state in step S3 is 0.01-0.05 MPa; the gas collected in step S4 is purified to obtain trimethylsilane.

[0015] This invention uses transition metals as catalysts to prepare trimethylsilane via a liquid-liquid-solid multiphase reaction under micro-positive pressure conditions. Compared with existing technologies, this invention has the following significant advantages: 1. This invention significantly shortens the reaction time: transition metal Pt, Ni, and Cu catalysts can effectively activate Si-Cl bonds and hydride anions, reduce the reaction activation energy, and combined with the increased contact area of ​​the liquid-liquid-solid system, shorten the reaction time from 10-15 hours to 1-3 hours, increasing production efficiency by 4-10 times.

[0016] 2. This invention significantly improves yield: By regulating the reaction equilibrium under micro-positive pressure conditions and combining the inhibitory effect of the catalyst on side reactions, the product yield can reach more than 92%, with a maximum of 98%, which is 15%-25% higher than the existing technology.

[0017] 3. This invention effectively reduces costs: the amount of catalyst used is only 0.5%-3% of the molar amount of the substrate, and it can be recycled and reused. At the same time, the amount of reducing agent is reduced by more than 30%. Combined with the reduction in energy consumption and equipment costs due to the shortened reaction time, the overall production cost is reduced by more than 30%.

[0018] 4. The reaction conditions of this invention are mild and controllable: it is carried out at 20-40℃ and 0.01-0.05MPa, without the need for high temperature and high pressure equipment. With nitrogen protection and precise drip rate control, the operation is highly safe and easy to scale up industrially. Detailed Implementation

[0019] Example 1 Solvent dehydration pretreatment: Take tetrahydrofuran, add it to molecular sieve at a mass percentage of 2%, stir for 7 hours and filter. The water content is 85 ppm. Set aside for later use. Solution preparation: Under nitrogen protection, weigh 4.8 g (0.12 mol) sodium borohydride and dissolve it in 30 mL of dehydrated and pretreated tetrahydrofuran to prepare a reducing agent solution; weigh 0.5 g (0.0026 mol) Pt ​​catalyst and add it to 10 mL of dehydrated and pretreated tetrahydrofuran to prepare a catalyst suspension; weigh 49.5 g (0.456 mol) trimethylchlorosilane and dissolve it in 50 mL of dehydrated and pretreated tetrahydrofuran to prepare a trimethylchlorosilane solution (substrate solution). Synthesis reaction: Two solutions were added dropwise to the substrate solution, with the reducing agent dropping at a rate of 3 d / s and the catalyst dropping at a rate of 1 d / s, and nitrogen was gently purged; the pressure was adjusted to 0.01 MPa, the temperature was controlled at 20℃ and the rotation speed at 100 r / min, and the reaction was carried out for 1 h; Product collection: 28.6 g of trimethylsilane was obtained, with a yield of 92.5%.

[0020] Example 2 Solvent dehydration pretreatment: Take tetrahydrofuran, add anhydrous calcium chloride at 1% by mass, stir for 6 hours, filter, water content 99ppm, and set aside. Solution preparation: Under nitrogen protection, weigh 15.2 g (0.4 mol) of lithium aluminum hydride and dissolve it in 40 mL of dehydrated and pretreated tetrahydrofuran to prepare a reducing agent solution; weigh 2.0 g (0.034 mol) of Ni catalyst and dissolve it in 15 mL of dehydrated and pretreated tetrahydrofuran to prepare a catalyst suspension; weigh 79.2 g (0.73 mol) of trimethylchlorosilane and dissolve it in 80 mL of dehydrated and pretreated tetrahydrofuran to prepare a trimethylchlorosilane solution; Synthesis reaction: reducing agent dropping rate 2d / s, catalyst dropping rate 5d / s, nitrogen light scavenging; pressure adjusted to 0.03MPa, temperature 30℃, rotation speed 150r / min, reaction time 2h; Product collection: 47.2 g of trimethylsilane was obtained, with a yield of 95.8%.

[0021] Example 3 Solvent dehydration pretreatment: Take tetrahydrofuran, add anhydrous magnesium chloride at 3% by mass, stir for 8 hours, filter, water content 82ppm, and set aside. Solution preparation: Under nitrogen protection, weigh 6.8 g (0.85 mol) of lithium hydride and dissolve it in 35 mL of dehydrated and pretreated tetrahydrofuran to prepare a reducing agent solution; weigh 1.2 g (0.02 mol) of Cu catalyst and dissolve it in 12 mL of dehydrated and pretreated tetrahydrofuran to prepare a catalyst suspension; weigh 59.4 g (0.547 mol) of trimethylchlorosilane and dissolve it in 60 mL of dehydrated and pretreated tetrahydrofuran to prepare a trimethylchlorosilane solution; Synthesis reaction: reducing agent dropping rate 1d / 2s, catalyst dropping rate 1d / s, nitrogen light scavenging; pressure adjusted to 0.05MPa, temperature 40℃, rotation speed 120r / min, reaction time 1.5h; Product collection: 34.5 g of trimethylsilane was obtained, with a yield of 94.1%.

[0022] Example 4 Water solvent pretreatment: Take tetrahydrofuran, add it to molecular sieve at a mass percentage of 5%, stir for 6.5 h, filter, water content 78 ppm, and set aside. Solution preparation: Under nitrogen protection, weigh 7.2 g (0.18 mol) sodium borohydride and 9.5 g (0.25 mol) lithium aluminum hydride, add 50 mL of dehydrated and pretreated tetrahydrofuran to dissolve and prepare a reducing agent solution; weigh 1.8 g (0.0094 mol Pt + 0.017 mol Ni) Pt-Ni composite catalyst, add 18 mL of dehydrated and pretreated tetrahydrofuran to prepare a catalyst suspension; weigh 99 g (0.912 mol) trimethylchlorosilane, dissolve in 100 mL of dehydrated and pretreated tetrahydrofuran to prepare a trimethylchlorosilane solution; Synthesis reaction: Reducing agent dropping rate 3d / s, catalyst dropping rate 3d / s, nitrogen light scavenging; pressure adjusted to 0.02MPa, temperature 25℃, rotation speed 180r / min, reaction time 2.5h; Product collection: 59.8 g of trimethylsilane was obtained, with a yield of 97.4%.

[0023] Example 5 Solvent dehydration pretreatment: Take tetrahydrofuran, add molecular sieve and anhydrous calcium chloride (1:1) at a mass percentage of 4%, stir for 7 hours and filter. The water content is 81 ppm. Set aside for later use. Solution preparation: Under nitrogen protection, weigh 4.0 g (0.1 mol) sodium borohydride and 3.4 g (0.425 mol) lithium hydride, add 25 mL of dehydrated and pretreated tetrahydrofuran to dissolve and prepare a reducing agent solution; weigh 0.9 g (0.0047 mol Pt + 0.01 mol Cu) Pt-Cu composite catalyst, add 10 mL of dehydrated and pretreated tetrahydrofuran to prepare a catalyst suspension; weigh 49.5 g (0.456 mol) trimethylchlorosilane, dissolve in 50 mL of dehydrated and pretreated tetrahydrofuran to prepare a trimethylchlorosilane solution; Synthesis reaction: reducing agent dropping rate 2d / s, catalyst dropping rate 1d / s, nitrogen light scavenging; pressure adjusted to 0.04MPa, temperature 35℃, rotation speed 200r / min, reaction time 1.5h; Product collection: 29.7 g of trimethylsilane was obtained, with a yield of 96.8%.

[0024] Comparative Example 1 The difference between this comparative example and Example 1 is that the preparation process of the reducing agent solution in step S2 is as follows: there is no nitrogen protection during the weighing and addition of the reducing agent to the reaction flask.

[0025] Product collection: 18.41 g of trimethylsilane was obtained, with a yield of 60%.

[0026] Comparative Example 2 The difference between this comparative example and Example 1 is that step S1, which involves dehydration pretreatment of the reaction solvent tetrahydrofuran, is missing. Product collection: 17.18 g of trimethylsilane was obtained, with a yield of 56%.

[0027] Comparative Example 3 The difference between this comparative example and Example 1 is that the reducing agent solution and the catalyst suspension are added at the same time.

[0028] Product collection: 25.47 g of trimethylsilane was obtained, with a yield of 83%.

[0029] In summary, the above are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing trimethylsilane, characterized in that, Includes the following steps: S1. The reaction solvent tetrahydrofuran is pretreated to remove water; S2. Using the dehydrated pretreated tetrahydrofuran, a reducing agent solution, a catalyst suspension, and a trimethylchlorosilane solution were prepared respectively. S3. Synthesis of trimethylsilane: A reducing agent solution and a catalyst suspension are added dropwise to a trimethylchlorosilane solution to construct a liquid-liquid-solid reaction system; the pressure of the reaction system is adjusted to a slightly positive pressure, and the system is stirred throughout the process at a temperature of 20-40℃ for 1-3 hours for hydrogenation reduction reaction. S4. Product collection: Collect the gases generated during the reaction.

2. The method for preparing trimethylsilane according to claim 1, characterized in that, The specific steps of step S1 are as follows: add a dehydrating agent to tetrahydrofuran, stir for 6-8 hours, filter, and obtain pretreated tetrahydrofuran with a water content ≤100ppm; The dehydrating agent is one or more of anhydrous calcium chloride, molecular sieve and anhydrous magnesium chloride, mixed in any proportion; The water-removing agent has a mass percentage content of 1-5%.

3. The method for preparing trimethylsilane according to claim 1, characterized in that, The preparation process of the reducing agent solution in step S2 is as follows: Under nitrogen protection, weigh the reducing agent and add it to the reaction flask, add the dehydrated and pretreated tetrahydrofuran, and stir until completely dissolved; the mass percentage of the reducing agent in the reducing agent solution is 5%-15%; The reducing agent is one or a mixture of lithium aluminum hydride, sodium borohydride, and lithium hydride.

4. The method for preparing trimethylsilane according to claim 1, characterized in that, The preparation process of the catalyst suspension in step S2 is as follows: weigh the transition metal catalyst, add tetrahydrofuran after dehydration pretreatment, and stir to form a suspension; The transition metal catalyst is one or more of Pt, Ni, and Cu catalysts; The mass percentage of transition metal catalyst in the catalyst suspension is 5-15%.

5. The method for preparing trimethylsilane according to claim 1, characterized in that, The preparation process of the trimethylchlorosilane solution in step S2 is as follows: weigh trimethylchlorosilane and completely dissolve it in tetrahydrofuran after dehydration pretreatment. The volume ratio of tetrahydrofuran after dehydration pretreatment to trimethylchlorosilane is 1:1-1.3:

1.

6. The method for preparing trimethylsilane according to claim 4, characterized in that, The amount of transition metal catalyst used in step S3 is 0.5%-3% of the molar amount of trimethylchlorosilane; the molar ratio of trimethylchlorosilane to reducing agent is 1:(0.3-0.8).

7. The method for preparing trimethylsilane according to claim 1, characterized in that, In step S3, the dropping rate of the reducing agent solution is 3d / s-1d / 5s; the dropping rate of the catalyst suspension is 1d / s-10d / s.

8. The method for preparing trimethylsilane according to claim 7, characterized in that, In step S3, the dropping rate of the reducing agent solution is 3 d / s; the dropping rate of the catalyst suspension is 1 d / s.

9. The method for preparing trimethylsilane according to claim 1, characterized in that, In step S3, the stirring speed is 100-200 r / min.

10. The method for preparing trimethylsilane according to claim 1, characterized in that, The pressure in the slightly positive pressure state in step S3 is 0.01-0.05 MPa; the gas collected in step S4 is purified to obtain trimethylsilane.