KR0179735B1 - Method of preparing dimethyldichlorosilane - Google Patents

Abstract

The present invention relates to a method for producing dimethyldichlorosilane, and more particularly, to a method of preparing dimethyldichlorosilane by reacting methyl chloride with silicon, wherein the silicon halide, tin or tin halide By adding a catalyst-based component consisting of a cargo, a zinc or zinc halide, and a cadmium or cadmium halide, greatly reducing the obstacles of the prior art in synthesizing dimethyldichlorosilane and ultimately the target compound. The yield of phosphorus dimethyldichlorosilane can be greatly increased, and it can be applied to more economical and competitive dimethyldichlorosilane production technology.

Description

Method for preparing dimethyldichlorosilane

The present invention relates to a method for producing dimethyldichlorosilane, and more particularly, to a method for producing dimethyldichlorosilane by reacting metal silicon powder with methyl chloride.

In general, the industrial processes for preparing organochlorinated silanes, in particular dimethyldichlorosilanes, are very well known and such processes are clearly described in US Pat. No. 2,380,995.

Organochlorinated silanes are prepared directly according to a synthesis process called Direct Synthesis or Synthesis of Rochow. In particular, the chemical reaction of copper to act as a catalyst to react the metal silicon powder and methyl chloride to obtain dimethyldichlorosilane is as follows.

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However, in the above reaction scheme, not only dimethyl dechlorosilane, which is a target compound, but also monomethyl trlochlorosilane, trimethyl monochlorosilane, dichloromethylsilane, etc. are produced together, and in addition, disilane compounds having high molecular weight and high boiling point are produced.

Of all the products obtained through direct synthesis, dimethyldichlorosilane is the most important compound. By hydrolyzing and polymerizing dimethyldichlorosilane, it is possible to obtain an oil and rubbery silicone polymer which is a basic material for the preparation of silicone. A process for preparing organosiloxane resins using dimethyldichlorosilane as a monomer has been presented in US Pat. No. 2,258,218. Further, US Pat. Nos. 2,469,888 and 2,469,830 disclose methods for preparing organosiloxane oils, and US Pat. No. 2,448,756 provide methods for preparing organosiloxane rubbers, respectively.

The products obtained by the direct synthesis method are separated and purified to obtain a high purity final product for each component. However, it is well known that the biggest obstacle to obtaining dimethyldichlorosilane with high purity is the separation process of monomethyltrichlorosilane and dimethyldichlorosilane, which have the highest yield among the byproducts.

To this end, it has already been proposed to add various additives in addition to copper to increase the production efficiency of dimethylchlorosilane. Additives include zinc or zinc halides (US Pat. No. 2,464,033), aluminum (US Pat. Nos. 2,403,370 and 2,427,605), tin, manganese, nickel and silver (British patent 1,207,466), cobalt (UK Patent 907,161, potassium chloride (USSR 307,650), phosphorus or phosphorus compounds (US Pat. No. 4,602,101), arsenic or arsenic compounds (US Pat. No. 4,762,940), barium and strontium (French Patent No. 85 02549) ), Cadmium or cadmium halides (US Pat. No. 3,446,829), zinc and cadmium (US Pat. No. 3,555,064), tin and antimony (French 950,448), lanthanide compounds (European Patent 0 470 020) , Al), zinc and tin (US Pat. No. 4,500,724).

However, by acting the additives, it was possible to improve the yield of the dimethyldichlorosilane synthesis reaction and the purity of the target compound by the direct synthesis method, but nevertheless the processes exhibited at least one of the following problems;

i) the selectivity of the average weight ratio of the produced monomethyltrichlorosilane and dimethyldichlorosilane (hereinafter referred to as T / D) and the dimethyldichlorosilane evaluated as the water concentration of dimethyldichlorosilane relative to the entire silane compound obtained is insufficient;

ii) reaction induction time and reaction temperature become very high;

iii) The reaction rate, which is defined as the input amount of silicon as the raw material and the weight of methyl chloride silane obtained in the reaction time (in the form of a mixture of the target compound and the byproduct), is lowered and the maximum conversion rate of the silicon is lowered. That is, the average activity of the catalyst system composed of copper and additives is insufficient; And

iv) Many by-products, especially disilane compounds, are produced. Accordingly, an object of the present invention is to solve the problems of the prior art described above and to provide an improved method for preparing dimethyldichlorosilane, which can ultimately increase the yield of dimethyldichlorosilane, which is a target compound.

Method for producing dimethyldichlorosilane of the present invention for achieving the above object, in the method for producing dimethyldichlorosilane by reacting methyl chloride with silicon, the halide of copper or copper, tin or halide of tin, It is characterized by the addition of a catalyst-based component consisting of a halide of zinc or zinc and a halide of cadmium or cadmium.

Hereinafter, the method for preparing dimethyldichlorosilane of the present invention will be described in more detail.

As described above, in the preparation of dimethyldichlorosilane by the direct synthesis method, not only dimethyldichlorosilane, which is a target compound, but also monomethyltrichlorosilane, trimethyl monochlorosilane, dichloromethylsilane, etc. are produced together with high molecular weight and high boiling point. Disilane compounds were produced.

Among them, the biggest obstacle was the separation of monomethyltrichlorosilane, which is the most produced in the by-products, and dimethyldichlorosilane, the target compound. To this end, various additives in addition to copper are added to increase the production efficiency of dimethyldichlorosilane. What has already been proposed. However, problems such as insufficient selectivity of dimethyldichlorosilane, prolongation of reaction time, and rise of reaction temperature are caused.

The present inventors first aimed at obtaining the following in order to present a process that can avoid or minimize the problems of the prior art as described above, a catalyst-based material and a method for preparing the same:

i) an increase in average selectivity to dimethyldichlorosilane;

ii) the increased initial selectivity at the beginning of the reaction is maintained until the catalyst component is finally deactivated;

iii) maximize the conversion of the raw material silicon; And

iv) Ultimately maximize yield for dimethyldichlorosilane.

Therefore, as a result of extensive research aimed at acquiring the above-mentioned matters in order to solve the problems of the prior art shown in the direct synthesis method of the above scheme, the type and amount of additives constituting the catalyst system have a high degree of selectivity and yield. Recognizing that these factors are key factors and conducting a series of studies based on these results, the addition of cadmium or cadmium halide to the proposed three-way catalyst system using copper, zinc and tin increases the selectivity and yield of dimethyldichlorosilane. Figured out.

Briefly, the method for producing dimethyldichlorosilane of the present invention is a method for producing dimethyldichlorosilane by reacting methyl chloride with silicon, wherein the silicon halide, tin or tin halide, zinc or zinc It is characterized by the addition of a halide of and a catalyst-based constituent consisting of cadmium or a halide of cadmium.

Meanwhile, the process for preparing dimethyldichlorosilane by reacting methyl chloride with silicon is as follows.

First, the raw material silicon is added to the organic solvent acetone or ether by adding a catalyst component consisting of copper or copper halides, tin or tin halides, zinc or zinc halides, and cadmium or cadmium halides. After mixing, the organic solvent is removed by drying at a predetermined temperature and pressure. When acetone is volatilized, it is possible to obtain silicon in which copper and additives are uniformly deposited. The reason for using the organic solvent acetone or ether is to uniformly mix the copper component, zinc component, tin component, cadmium components of the catalyst system with the raw material silicon.

On the other hand, the catalyst component may be selectively added to each of the raw material silicon.

In the case of copper or copper halides, the content of pure copper in copper or copper halides is preferably about 1 to 20 parts by weight relative to the content of silicon. The content of pure tin in the tin or halide of tin is preferably about 50 to 2000 ppm with respect to the content of pure copper. The content of pure cadmium in cadmium or cadmium halide is preferably about 0.0001 to 2.0 parts by weight based on the content of pure copper. As for the content of pure zinc in zinc or a halide of zinc, 0.1-20 weight part is preferable with respect to content of pure copper.

This silicon is placed in a reactor, and the raw material is dried at a predetermined temperature and a nitrogen atmosphere. Then, silicon tetrachloride is produced by reacting copper chloride and silicon at a predetermined temperature. Upon completion of this reaction, the catalyst is heated to a predetermined temperature to activate the catalyst and reacted with methyl chloride gas at a temperature of about 250 to 350 ° C. to terminate the dimethyldichlorosilane manufacturing process. In this case, the synthesis of dimethyldichlorosilane is preferably carried out in a stirred reactor, a comparative semi-fluidized bed reactor, a fixed bed reactor or a batch reactor.

Therefore, the present invention is a new and advanced method for obtaining high purity dimethyldichlorosilane by the direct synthesis method of the above scheme, and can be sufficiently applied to the economic production technology of dimethyldichlorosilane, which is the basic raw material of the most widely used silicon industry. .

Hereinafter, the present invention will be described in more detail with reference to examples of the present invention and comparative examples of the related art, but this does not limit the scope of the present invention.

Example 1

50 g of silicon, 3.9 g of copper (I) chloride (the net content of copper is 5 parts by weight for silicon), 0.502 g of zinc chloride (10 parts by weight for copper), 0.OO3 g of tin (1200 ppm for copper), chloride 0.025 g of cadmium (0.6 parts by weight of copper) was added to 50 ml of acetone and mixed well, followed by drying at 120 ° C. and 5 torr to remove acetone. When acetone is volatilized, it is possible to obtain silicon in which copper and additives are uniformly deposited. The silicon was placed in a tubular fluidized bed reactor having an inner diameter of 3.5 cm and a length of 60 cm equipped with a triple stirring vane, flowing nitrogen at 230 ° C., and dried. When tetrachloride was reacted with silicon at 310 ° C, silane tetrachloride was generated. Upon completion of this reaction, the catalyst was heated to 380 ° C. to activate the catalyst for 4 hours and reacted with methyl chloride gas at 300 ° C.

The injection flow rate of methyl chloride gas was 90 ml / min, and the total reaction time was 40 hours. The purity (measured by gas chromatography) of large methyldichlorosilane in the obtained silane was 92.0%, and the production ratio T / D of trichloromethylsilane and dimethyldichlorosilane was 0.03. In addition, the conversion of silicon was 92% based on the amount of silicon remaining, and the yield of dimethyldichlorosilane was 85%.

Example 2

In the same manner as described in Example 1, 50 g of silicon, 3.9 g of copper (I) chloride (net content of copper is 5 parts by weight for silicon), 0.502 g of zinc chloride (10 parts by weight of copper), tin 0.003 g (which is 1600 ppm for copper) and 0.025 g of cadmium chloride (0.6 parts by weight for copper) were mixed and dried in acetone 60 ml solvent to obtain silicon with copper and additives deposited uniformly. This was placed in a reactor, and nitrogen was supplied at 230 ° C. to dry the raw materials. After copper chloride and silicon were reacted at 310 ° C., the catalyst was activated at 380 ° C. for 2 hours and reacted with methyl chloride gas at 300 ° C. The injection flow rate of methyl chloride gas was 90 ml / min, and the total reaction time was 34 hours.

The purity (measured by gas chromatography) of dimethyldichlorosilane in the obtained silane was 92.5%, and the production ratio T / D of trichloromethylsilane and dimethyldichlorosilane was 0.03. The conversion of silicone was 86% and the yield of dimethyldichlorosilane was 80.0%.

Example 3

In the same manner as described in Example 1, 75 g of silicon, 6.5 g of copper (I) (the net content of copper is 6 parts by weight for silicon), 0.7 g of zinc chloride (8 parts by weight of copper), tin 0.005 g (1000 ppm for copper) and 0.03 g of cadmium chloride (0.4 parts by weight for copper) were mixed and dried in 100 ml of acetone to obtain silicon with copper and additives deposited uniformly.

It was put in a reactor and flowed nitrogen at 230 ℃ conditions to dry the raw material. After copper chloride and silicon were reacted at 310 ° C., the catalyst was activated for 7 hours at a high temperature of 400 ° C., and reacted with methyl chloride gas at 300 ° C. The injection flow rate of methyl chloride gas was 120 ml / min, and the total reaction time was 23.5 hours. The purity of the dimethyldichlorosilane in the obtained silane (measured by gas chromatography) was 93.6%, and the production ratio T / D of trichloromethylsilane and dimethyldichlorosilane was 0.02. The conversion of silicon was 93% and the yield of dimethyldichlorosilane was 87.0%.

Comparative Example 1

[European Patent 0470 020, A1]

Into a 6 mm cylindrical fluidized bed reactor equipped with a metal stirrer and a gas distributor was placed a powdered mixture consisting of the following components:

-CuCl: 16.3g (5 parts by weight of pure copper relative to silicon)

-Bronze with 10% Sn content: 0.38g

-ZnCl ₂ : 1.6g (the content of pure zinc relative to silicon is 0.37 parts by weight)

Cs ₃ LaCl ₆ : 1.58 g (synthesized from CsCI and LaCl ₃ )

The reactor was heated to 315 ° C while flowing nitrogen, and then reacted by injecting methyl chloride gas. The purity of dimethyldichlorosilane in the obtained silane was 94.3%, and the production ratio T / D of trichloromethylsilane and dimethyldichlorosilane silicon was 0.03. The conversion of silicone was 59% and the yield of dimethyldichlorosilane was 55%.

Therefore, the present invention can greatly reduce the obstacles of the prior art in synthesizing dimethyldichlorosilane and ultimately increase the yield of dimethyldichlorosilane, which is a target compound. Therefore, it is possible to apply to more economical and competitive dimethyldichlorosilane production technology.

Claims (8)

A method for preparing dimethyldichlorosilane by reacting methyl chloride with silicon, the method comprising: a silicon halide of copper or copper, a halide of tin or tin, a halide of zinc or zinc, and a halide of cadmium or cadmium A process for preparing dimethyldichlorosilane, characterized by adding a catalyst component. The method for producing dimethyldichlorosilane according to claim 1, wherein the content of pure copper in the halide of copper or copper in the catalyst component is 1-20 parts by weight based on the content of silicon. The method for preparing dimethyldichlorosilane according to claim 1, wherein the content of pure tin in the halide of tin or tin in the catalyst component is 50 to 2000 ppm with respect to the content of pure copper. The method for producing dimethyldichlorosilane according to claim 1, wherein the content of pure zinc in the halide of zinc or zinc in the catalyst component is 0.1-20 parts by weight based on the content of pure copper. The method for preparing dimethyldichlorosilane according to claim 1, wherein the content of pure cadmium in cadmium or cadmium halide in the catalyst component is 0.0001 to 2.0 parts by weight based on the content of pure copper. The process for preparing dimethyldichlorosilane according to claim 1, wherein the process for preparing dimethyldichlorosilane is performed in one reactor selected from the group consisting of a stirred fluidized bed reactor, a comparative semifluidized fluidized bed reactor, a fixed bed reactor and a batch reactor. The method for producing dimethyldichlorosilane according to claim 1, wherein the synthesis temperature of dimethyldichlorosilane is 250 to 350 ° C. The method of claim 1, wherein the catalyst component is used as an organic solvent of acetone or ether to uniformly mix the main component with silicon as the main raw material.