CN114736233B

CN114736233B - Synthesis method of tetramethylsilane

Info

Publication number: CN114736233B
Application number: CN202210647021.7A
Authority: CN
Inventors: 徐聪; 徐浩; 陈琪; 栗鹏伟; 刘冬妮; 孙猛; 孔超
Original assignee: Suzhou Jinhong Gas Co Ltd
Current assignee: Jinhong Gas Co.,Ltd.
Priority date: 2022-06-09
Filing date: 2022-06-09
Publication date: 2022-08-26
Anticipated expiration: 2042-06-09
Also published as: CN114736233A

Abstract

The invention discloses a synthetic method of tetramethylsilane, which comprises the following steps: hexamethyldisiloxane is used as a raw material and reacts in a methyllithium solution to obtain tetramethylsilane. By optimizing the reaction system and the reaction route design, the optimization and improvement in the aspects of raw material cost, reaction conditions, yield and the like are realized, so that the current situation of tetramethylsilane production, popularization and application is effectively improved.

Description

Synthesis method of tetramethylsilane

Technical Field

The invention relates to fine chemical synthesis, in particular to a synthesis method of tetramethylsilane.

Background

4MS, also known as TMS, is an important organic silicon material with the Chinese name of tetramethylsilane, and has wide application in the fields of medicine, aerospace construction, mechanical materials and the like. The ultra-high purity (mass fraction is more than or equal to 99.99 percent) 4MS can be used as a precursor of Chemical Vapor Deposition (CVD) or Plasma Enhanced Chemical Vapor Deposition (PECVD) in the electronic industry and used for preparing high-quality silicon carbide films. TMS is a precursor material for low dielectric constant film deposition in the process of super-large scale integrated circuit, belongs to a new material in the market, and is mainly used as an etching barrier layer and a copper barrier layer in the process of integrated circuit copper chips below 90 nm.

Industrially, methyl chlorosilane is synthesized by methyl chloride and silicon powder in a direct method under the catalysis of copper. In the direct synthesis process, the main product is dimethyldichlorosilane accounting for more than 80% of the total amount, and simultaneously, a large amount of methyl chlorosilane mixtures can be generated, including methyl trichlorosilane, trimethylchlorosilane, methyl dichlorosilane, low-boiling-point silane mixtures (short for low-boiling-point substances, LBR), high-boiling-point silane mixtures (short for high-boiling-point substances, HBR) and the like. The low boiling point substance contains about 40% of 4MS, and the method of enrichment and purification from the low boiling point mixture constitutes the main preparation method of 4MS at present. The method has higher economic value, and if the purification method is adopted for enrichment and purification, the low-boiling-point substance hazardous waste discharge of enterprises can be effectively reduced, and the enterprise benefit can be increased. However, the method has more impurities generated by synthesis, and the impurity isopentane (30 ℃) with the boiling point (26 ℃ -28 ℃) close to that of the target product 4MS exists, and the 4MS and organic impurities such as isopentane, 2-pentene, cyclopropylethane and the like have an azeotropic phenomenon in the rectification process, so that the purification difficulty is high.

In addition to enrichment using LBR, synthetic methods can be used to prepare 4 MS. Tetrachlorosilane or tetraethoxysilane is used as a silicon source, methyl magnesium iodide is used as a methyl source, 4MS with low and medium yield can be realized under the laboratory condition and the low-temperature anhydrous oxygen-free condition, and the method cannot be applied to large-scale industrial production.

The information disclosed in this background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art that is already known to a person skilled in the art.

Disclosure of Invention

The invention aims to provide a tetramethylsilane synthesis method, which uses an easily available raw material hexamethyldisiloxane as a raw material, can realize high yield under room temperature reaction conditions, can obtain a 4MS product with the yield of more than 80 percent through GC-MS tests, and can be directly applied to industrial production under mild conditions.

In order to achieve the above object, an embodiment of the present invention provides a method for synthesizing tetramethylsilane, including: hexamethyldisiloxane is used as a raw material and reacts in a methyllithium solution to obtain tetramethylsilane.

In one or more embodiments of the present invention, the solvent in the methyllithium solution is diethoxymethane.

In one or more embodiments of the present invention, the concentration of methyllithium in the methyllithium solution is: 2.7 mol/L.

In one or more embodiments of the present invention, the charge ratio of hexamethyldisiloxane to methyllithium, in terms of mole ratios, is: hexamethyldisiloxane: methyllithium =1 (1.5-2.0).

In one or more embodiments of the present invention, the reaction conditions are not higher than room temperature under a protective atmosphere. Preferably, the reaction conditions are under a protective atmosphere of 0 deg.C (e.g., in an ice water bath). Preferably, stirring is carried out during the reaction.

In one or more embodiments of the invention, the shielding gas of the protective atmosphere is selected from nitrogen, argon, helium.

In one or more embodiments of the present invention, the method further comprises quenching the reaction by adding a quenching agent to the reaction system at the end of the reaction (the end of the reaction means that the reaction is in a sufficient time and the stirring is stopped).

In one or more embodiments of the invention, the quenching agent is selected from a saturated aqueous solution of ammonium chloride.

In one or more embodiments of the invention, the amount of quencher used in the reaction system is 1.0 to 1.5 times the molar equivalent of the charge of methyllithium.

Compared with the prior art, according to the synthetic method of tetramethylsilane, the reaction is prepared by reacting tetrachlorosilane or tetraethoxysilane with methyl magnesium iodide, the synthetic condition is mild, the reaction can be carried out only at room temperature or below, a low-temperature reactor is not needed, side reactions are fewer, and the reaction is carried out almost in a stoichiometric ratio.

Compared with chloromethane and silicon powder which are prepared by reaction in the presence of a copper catalyst, the method has the advantages of low difficulty in subsequent rectification and purification, fewer side reactions, reaction almost in stoichiometric ratio, high yield and suitability for industrial production.

Compared with the method for purifying low-boiling-point substances in the production process of organic silicon, the method has the advantages of low difficulty in subsequent rectification and purification, more material boiling points, simple purification process and no uncontrollable substances in the product, and can meet the production and use requirements of the semiconductor industry for tetramethylsilane.

Detailed Description

The technical solution of the present invention is described in detail below with reference to the specific embodiments of the present invention, but it should be understood that the scope of the present invention is not limited by the specific embodiments.

Throughout the specification and claims, unless explicitly stated otherwise, the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated element or component but not the exclusion of any other element or component.

The reaction equation is as follows:

hexamethyldisiloxane is used as a raw material, diethoxymethane solution of methyllithium is added into the hexamethyldisiloxane, and the reaction can be carried out at room temperature or 0 ℃ to generate lithium oxide precipitate and a tetramethylsilane crude product. Quenching and distilling the reacted product to obtain the tetramethylsilane product with higher purity.

Example 1:

taking 1mol of hexamethyldisiloxane, reacting with 600mL of diethoxymethane solution (2.7 mol/L) of methyl lithium in a 1.5L round-bottom flask under stirring for 12h in an ice-water bath under the protection of nitrogen, stopping the reaction, adding 100mL of saturated ammonium chloride aqueous solution under the condition of the ice-water bath for quenching, and distilling to obtain 120g of a component with the temperature of 26-30 ℃, wherein the yield is 84.0%, and the purity is 93.9% by GC-MS.

Example 2:

taking 1mol of hexamethyldisiloxane, reacting with 700mL of diethoxymethane solution (2.7 mol/L) of methyl lithium in a 1.5L round-bottom flask under stirring for 12h in an ice-water bath under the protection of nitrogen, stopping the reaction, adding 100mL of saturated ammonium chloride aqueous solution under the condition of the ice-water bath for quenching, and distilling to obtain 151g of a component at 26-30 ℃, wherein the yield is 90.6%, and the purity is 94.1% by GC-MS.

Comparative example 1:

1mol of hexamethyldisiloxane and 600mL of a methyl lithium ether solution (3.1 mol/L) are put into a 1.5L round-bottom flask, the reaction is stopped after the hexamethyldisiloxane and the methyl lithium ether solution are stirred and react for 12 hours in an ice-water bath under the protection of nitrogen, 100mL of saturated ammonium chloride aqueous solution is slowly added for quenching under the conditions of minus 10 ℃ to minus 30 ℃ (cold hydrazine or dry ice bath), then the product is distilled to obtain 124g of a component with the temperature of 26-30 ℃, the yield is 75.6%, the GC-MS test purity is 83.1%, and the other main impurities are ether.

Comparative example 2:

taking 1mol of hexamethyldisiloxane, reacting with 1200mL of diethoxymethane solution (1.6 mol/L) of methyl lithium in a 3L round-bottom flask under stirring for 12h in an ice-water bath under the protection of nitrogen, stopping the reaction, adding 100mL of saturated ammonium chloride aqueous solution under the condition of the ice-water bath for quenching, and distilling to obtain 131g of a component at 26-30 ℃, wherein the yield is 77.3%, and the purity is 92.9% by GC-MS test.

Example 3:

taking 1mol of hexamethyldisiloxane and 600mL of diethoxymethane solution (2.7 mol/L) of methyllithium in a 1.5L round-bottom flask, stirring and reacting for 12h in an ice-water bath under the protection of argon, stopping the reaction, adding 200mL of 75% ethanol aqueous solution under the condition of the ice-water bath for quenching, and distilling to obtain 119g of a component at 26-30 ℃, wherein the yield is 83.3%, and the purity is 90.1% by GC-MS test.

Comparative example 3:

taking 1mol of hexamethyldisiloxane and 741mL of diethoxymethane solution (2.7 mol/L) of methyllithium in a 1.5L round-bottom flask, stirring and reacting for 2h in an ice-water bath under the protection of helium, stopping the reaction, adding 100mL of saturated ammonium chloride aqueous solution under the condition of the ice-water bath for quenching, and distilling to obtain 45g of components at 26-30 ℃, wherein the yield is 31.5%, and the purity is 87.9% by GC-MS test.

Example 4:

taking 1mol of hexamethyldisiloxane and 600mL of diethoxymethane solution (2.7 mol/L) of methyllithium in a 1.5L round-bottom flask, stirring and reacting for 6h in an ice-water bath under the protection of helium, stopping the reaction, adding 100mL of saturated ammonium chloride aqueous solution under the condition of the ice-water bath for quenching, and distilling to obtain 107g of a component with the temperature of 26-30 ℃, wherein the yield is 74.9%, and the purity is 92.0% by GC-MS test.

Example 5:

taking 1mol of hexamethyldisiloxane, reacting with 600mL of diethoxymethane solution (2.7 mol/L) of methyllithium in a 1.5L round-bottom flask under the protection of argon in an ice-water bath for 24 hours under stirring, stopping the reaction, adding 100mL of saturated ammonium chloride aqueous solution under the condition of the ice-water bath for quenching, and distilling to obtain 131g of a component at 26-30 ℃, wherein the yield is 91.7%, and the purity is 93.7% by GC-MS test.

Comparative example 5:

taking 1mol of hexamethyldisiloxane and 600mL of diethoxymethane solution (2.7 mol/L) of methyllithium in a 1.5L round-bottom flask, stirring and reacting for 24h in an ice-water bath under the protection of argon, stopping the reaction, slowly dropwise adding 100mL of 75% ethanol water solution under the condition of the ice-water bath for quenching, and strictly controlling the dropwise adding speed in the quenching process. After quenching was complete, distillation gave 131g of 26-30 ℃ fraction in 91.7% yield and 87.1% purity by GC-MS with about 2% ethanol as impurity.

The foregoing descriptions of specific exemplary embodiments of the present invention have been presented for purposes of illustration and description. It is not intended to limit the invention to the precise form disclosed, and obviously many modifications and variations are possible in light of the above teaching. The exemplary embodiments were chosen and described in order to explain certain principles of the invention and its practical application to enable one skilled in the art to make and use various exemplary embodiments of the invention and various alternatives and modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims and their equivalents.

Claims

1. A method for synthesizing tetramethylsilane is characterized by comprising the following steps: hexamethyldisiloxane is used as a raw material, the hexamethyldisiloxane reacts in a methyllithium solution, a quenching agent is added into a reaction system at the end point of the reaction for quenching, and tetramethylsilane is obtained, wherein a solvent in the methyllithium solution is diethoxymethane, and the concentration of methyllithium in the methyllithium solution is as follows: 2.7mol/L, the charging ratio of hexamethyldisiloxane to methyllithium, and the molar ratio: hexamethyldisiloxane: and (2) methyllithium =1, (1.5-2.0), the reaction is carried out under the condition of not higher than room temperature in a protective atmosphere, the quenching agent is selected from saturated aqueous solution of ammonium chloride, and the dosage of the quenching agent in the reaction system is 1.0-1.5 times of the feeding amount of the methyllithium.

2. The method for synthesizing tetramethylsilane according to claim 1, wherein the reaction is carried out under a protective atmosphere at 0 ℃.

3. The method for synthesizing tetramethylsilane according to claim 2, wherein the protective gas of the protective atmosphere is selected from nitrogen, argon, helium.