Method for removing impurities in diethoxymethylsilane

Abstract

The invention provides a method for removing impurities in diethoxymethylsilane, and belongs to the field of purification. The method provided by the invention comprises the following steps: mixing diethoxymethylsilane with a metal chelating agent, and carrying out chelation reaction to obtain a reaction solution; mixing the reaction liquid, an entrainer and an ether complexing agent, performing complexing-azeotropy-reduced pressure rectification, and removing light components to obtain a reaction system; and heavy components in the reaction system are removed. By adopting the metal chelating agent, double effects can be realized: trace moisture in DEMS is adsorbed, and side reaction caused by the trace moisture is avoided; and various metal ion impurities are removed through efficient chelation. In the complexing-azeotropic-reduced pressure distillation process, an azeotrope agent and a substance with a boiling point close to that of DEMS form an azeotrope, so that the separation difficulty is reduced; the ether complexing agent can specifically capture impurities such as B and P and transfer the impurities into the heavy component; finally, DEMS purification is realized by utilizing the difference of boiling points of the components.

Description

Technical Field

[0001] This invention relates to the field of purification, and more specifically to a method for removing impurities from diethoxymethylsilane. Background Technology

[0002] In the electronics industry, as the linewidth of integrated circuits continues to shrink, lower dielectric constants are required for interlayer dielectrics to reduce interconnect delay. To reduce interconnect delay, transistor resistance-capacitance delay, and interconnect delay, low-dielectric materials are needed. Diethoxymethylsilane (DEMS) has a low dielectric constant and can be used as a precursor for depositing interlayer dielectrics.

[0003] During DEMS deposition, metal contamination, particles, and silicon surface roughness can all affect transistor performance, thus requiring high DEMS purity. Existing DEMS purification processes mainly employ two methods: First, a single atmospheric or vacuum distillation method. This method does not perform DEMS pretreatment, leading to side reactions during distillation, increased impurities, difficulty in removing organic components, and low efficiency in removing metallic / non-metallic impurities, resulting in significant product loss, unsatisfactory yields, and substandard chloride and ethanol levels. Second, the chloride scavenger method. This method adds a chloride scavenger to the purified sample. While it can specifically remove chlorides, it requires precise control of the scavenger dosage, making the operation complex and demanding on process parameters. Furthermore, the presence of chloride scavenger residue increases the difficulty of industrial application. Summary of the Invention

[0004] This invention provides a method for removing impurities from diethoxymethylsilane. The method of this invention solves the problems of side reactions, difficulty in removing impurities, and incomplete removal of organic components in the purification process of the prior art. The product prepared by this method has a purity of 4N5 or higher, the total impurities of metal ions and non-metal ions are less than 1 ppb, the ethanol impurity content is less than 0.005%, and the chloride ion content is less than 0.5 ppm, which meets the requirements of high-end electronic application fields such as semiconductor manufacturing.

[0005] This invention provides a method for removing impurities from diethoxymethylsilane, comprising the following steps: Diethoxymethylsilane was mixed with a metal chelating agent and then subjected to a chelation reaction to obtain a reaction solution; The reaction solution, azeotropic agent and ether complexing agent are mixed and then subjected to complexation-azeotropic-reduced pressure distillation to remove light components and obtain the reaction system. Remove heavy components from the reaction system.

[0006] Preferably, the impurities of the diethoxymethylsilane include, but are not limited to, methanol, ethanol, chlorosilane, ethoxymethylsilane, triethoxymethylsilane, acetal, triethoxymethoxysilane, metal compounds and non-metal compounds; The metallic elements in the metal compound include one or more of Li, Na, Mg, Al, K, Ca, Zn, Fe, Cu, Ag, V, Ti, Mn, Co, Cr, Pb, and Ga; The nonmetallic elements in the nonmetallic compound include one or more of As, B, and P.

[0007] Preferably, the metal chelating agent includes one or more of the following: diethylenetriaminepentaacetic acid, hypozinotriacetic acid, hydroxyethylethylenediaminetriacetic acid, ethylene glycol diethyl ether diaminetetraacetic acid, tetrasodium glutamate diacetate, tetrasodium iminodisuccinate, trisodium methylglycine diacetate, hydroxyethylenediphosphonic acid, sodium gluconate, citric acid, and ethylenediaminedisuccinic acid.

[0008] Preferably, the mass ratio of diethoxymethylsilane to metal chelating agent is 500~2000:1.

[0009] Preferably, the chelation reaction is carried out at a temperature of 25~40℃ for 6 hours; The chelation reaction was carried out under stirring conditions; The chelation reaction further includes: filtering the system obtained from the chelation reaction to obtain the reaction solution; The filtration device used in the filtration process has a micropore diameter of 100~500nm and a filtration accuracy of less than 200nm.

[0010] Preferably, the azeotropic agent includes one or more of n-hexane, pentane, isohexane, 3-methylpentane, neohexane, and n-pentane.

[0011] Preferably, the mass ratio of diethoxymethylsilane to azeotropic agent is 500~1000:1.

[0012] Preferably, the ether complexing agent includes one or more of p-bromoanisole, diphenyl ether, crown ether, azacrown ether, crypt ether, spherical ether, anisole, p-methylanisole, anethole, benzyl ethyl ether, benzyl phenyl ether, benzofuran, and dibenzofuran.

[0013] Preferably, the mass ratio of diethoxymethylsilane to ether complexing agent is 3000~8000:1.

[0014] Preferably, the complexation-azeotropic-reduced pressure distillation is carried out in a light-light-removal column; The temperature of the condensate at the top of the light-weight removal tower is -20~5℃; the temperature at the bottom of the tower is 60~90℃. The reflux ratio of the complexation-azeotropic-reduced pressure distillation is 3~8:1, and the pressure is -95~-20kPa; The temperature of the condensate at the top of the heavy component removal tower is -20~5℃, and the temperature at the bottom of the tower is 60~90℃. The reflux ratio for the removal of the heavy components is 3~10:1, and the pressure is -95~-20Kpa.

[0015] This invention combines the distribution and properties of ionic impurities in DEMS with the use of metal chelating agents, achieving the following dual effects simultaneously: firstly, it adsorbs trace amounts of moisture in DEMS, preventing side reactions; secondly, it efficiently chelates and removes various metal ion impurities. This invention innovatively employs a complexation-azeotropic-reduced pressure distillation process. During reduced pressure distillation, the azeotropic agent forms an azeotrope with substances whose boiling points are close to those of DEMS, thereby reducing the difficulty of separation. Simultaneously, ether-based complexing agents specifically capture impurities such as B and P, forming stable molecular complexes and transferring them to the heavier components. Finally, by utilizing the differences in boiling points between the components, efficient purification of DEMS and deep removal of impurities are achieved. Example results show that the method of this invention can improve the purity of DEMS products to over 99.995% (4N5), control the ionic impurity content to below 1 ppb, the ethanol impurity content to less than 0.005%, and the chloride ion content to less than 0.5 ppm, while maintaining excellent yield, obtaining DEMS products that meet the requirements of high-end electronic applications such as semiconductor manufacturing.

[0016] The method of this invention has a simple process flow, low loss, low impurities, high yield, and no pollution. The resulting DEMS products meet the requirements of high-end electronic applications such as semiconductor manufacturing. Attached Figure Description

[0017] Figure 1 This is an example of an apparatus used to remove impurities from diethoxymethylsilane. Detailed Implementation

[0018] This invention provides a method for removing impurities from diethoxymethylsilane, comprising the following steps: Diethoxymethylsilane was mixed with a metal chelating agent and then subjected to a chelation reaction to obtain a reaction solution; The reaction solution, azeotropic agent and ether complexing agent are mixed and then subjected to complexation-azeotropic-reduced pressure distillation to remove light components and obtain the reaction system. Remove heavy components from the reaction system.

[0019] In this invention, diethoxymethylsilane is mixed with a metal chelating agent and then subjected to a chelation reaction to obtain a reaction solution.

[0020] In this invention, the mass ratio of diethoxymethylsilane to metal chelating agent is preferably 500-2000:1. In specific embodiments of this invention, it can be 600:1, 700:1, 800:1, 900:1, 1000:1, 1100:1, 1200:1, 1300:1, 1400:1, 1500:1, 1600:1, 1700:1, 1800:1, or 1900:1.

[0021] In this invention, the preferred impurities in the diethoxymethylsilane component include, but are not limited to, methanol, ethanol, chlorosilane, ethoxymethylsilane, triethoxymethylsilane, acetal, triethoxymethoxysilane, metal compounds, and non-metal compounds; the metal elements in the metal compounds include one or more of Li, Na, Mg, Al, K, Ca, Zn, Fe, Cu, Ag, V, Ti, Mn, Co, Cr, Pb, and Ga; the non-metal elements in the non-metal compounds include one or more of As, B, and P.

[0022] In this invention, the metal chelating agent preferably comprises one or more of the following: diethyltriaminepentaacetic acid (DTPA), nitrotriacetic acid (NTA), hydroxyethylethylenediaminetriacetic acid (HEDTA), ethylene glycol diethyl ether diaminetetraacetic acid (EGTA), tetrasodium glutamate diacetate (GLDA), tetrasodium iminodisuccinate (IDS), trisodium methylglycine diacetate (MGDA), hydroxyethylidene diphosphonic acid (HEDP), sodium gluconate, citric acid, and ethylenediaminedisuccinic acid; the purity of the metal chelating agent is ≥99.9%, and the total impurities are ≤50 ppb.

[0023] In this invention, the chelation reaction is preferably carried out at a temperature of 25-40°C and for a time of 6 hours; the chelation reaction is preferably carried out under stirring conditions.

[0024] The mechanism of chelation reactions is mainly based on the efficient capture ability of multiple coordinating atoms (such as O, N, S, etc.) in the chelating agent molecule for metal ions: the coordinating atoms can cooperate with free metal ions (such as Fe) in the solution. 3+ Cu 2+ Ni 2+ Ca 2+ Mg 2+ (e.g., metal ions) coordinate to form stable cyclic chelates. This process not only effectively immobilizes metal impurities but also disrupts the original binding of metal ions with water molecules, thereby inhibiting water-induced side reactions and ultimately achieving the purification goal of simultaneously removing metal ions and trace amounts of water from DEMS.

[0025] After the chelation reaction, the present invention preferably further includes: filtering the system obtained by the chelation reaction to obtain the reaction solution.

[0026] In this invention, the micropore diameter of the filtration device used for filtration is preferably 100~500nm, and the filtration accuracy is less than 200nm. In specific embodiments of this invention, the micropore diameter can be 200, 300 or 400nm; the material of the filtration device preferably includes polytetrafluoroethylene or stainless steel.

[0027] Filtering insoluble precipitates prevents blockage of the pipeline between the chelation reaction unit and the light-weight removal tower, while also allowing for the recovery, activation, and reuse of the chelating agent. Furthermore, filtration enables liquid-solid separation, avoiding the introduction of ionic impurities into the DEMS product. This design significantly improves the reaction selectivity and separation efficiency of the purification process.

[0028] After obtaining the reaction solution, the present invention mixes the reaction solution, azeotropic agent and ether complexing agent and then performs complexation-azeotropic-reduced pressure distillation to remove light components and obtain the reaction system.

[0029] In this invention, the mass ratio of diethoxymethylsilane to the azeotropic agent is preferably 500-1000:1, and in specific embodiments, it can be 600:1, 700:1, 800:1, 900:1, or 1000:1. The azeotropic agent preferably includes one or more of n-hexane, pentane, isohexane, 3-methylpentane, neohexane, and n-pentane. The purity of the azeotropic agent is preferably greater than 99%, and the total impurities are preferably less than 50 ppb. The mechanism of action of DEMS and the azeotropic agent is mainly to solve the problem that during the DEMS distillation and purification process, ethanol easily forms azeotropic compounds with temperatures close to DEMS, such as diethoxydimethylsilane, 1,1-dimethoxyethane, 1,1-diethoxyethane, ethoxymethoxymethane, and diethoxymethane, making it difficult to separate the component impurities. The azeotrope formed by ethanol and alkanes has a boiling point much lower than that of DEMS, making it easy to separate and reducing the difficulty of DEMS purification.

[0030] In this invention, the mass ratio of diethoxymethylsilane to ether complexing agent is preferably 3000-8000:1, and in specific embodiments of this invention, it can be 3500:1, 4000:1, 4500:1, 5000:1, 5500:1, 6000:1, 6500:1, 7000:1, or 7500:1; the ether complexing agent preferably includes one or more of p-bromoanisole, diphenyl ether, crown ether, azacrown ether, cryptane, spherical ether, anisole, p-methylanisole, anethole, benzyl ethyl ether, benzyl phenyl ether, benzofuran, and dibenzofuran.

[0031] In this invention, the complexation-azeotropic-reduced pressure distillation is carried out in a light-light-removal column; the preferred temperature of the condensate at the top of the light-light-removal column is -20~5℃, and in specific embodiments of this invention, it can be -15℃, -10℃, -5℃ or 0℃; the preferred temperature of the column bottom is 60~90℃, and in specific embodiments of this invention, it can be 65℃, 70℃, 75℃, 80℃ or 85℃. In this invention, the reflux ratio of the complexation-azeotropic-reduced pressure distillation is preferably 3 to 8:1, and the pressure is preferably -95 to -20 kPa. In specific embodiments of this invention, the reflux ratio for the removal of light components can be 4:1, 5:1, 6:1, or 7:1, and the pressure can be -90 kPa, -80 kPa, -70 kPa, -60 kPa, -50 kPa, -40 kPa, -30 kPa, or -20 kPa.

[0032] The complexation between DEMS and ether complexing agents has three major advantages: First, the boron anion forms a BO coordinate bond with the lone pair electrons of the oxygen atom in the ether molecule, thereby achieving selective removal of boron; second, the ether complexing agent itself has a specific cavity structure, which can capture ionic impurities such as boron and phosphorus through the size matching effect; and third, the boiling point of the ether complexing agent is much higher than that of DEMS, avoiding the presence of unremoved ether substances in the DEMS product.

[0033] The light component removal process achieves the removal of low-boiling components and impurities such as methanol, ethanol, ethanol-alkane azeotropes, C3, and chlorides.

[0034] In this invention, the temperature of the condensate at the top of the de-heavy component removal tower is preferably -20~5℃, and the temperature at the bottom of the tower is preferably 60~90℃. In specific embodiments of this invention, it can be 65℃, 70℃, 75℃, 80℃ or 85℃. After obtaining the reaction system, the present invention removes heavy components and impurities from the reaction system.

[0035] In this invention, the reflux ratio for removing the heavy components is 3 to 10:1, and the pressure is -95 to -20 kPa. In specific embodiments of this invention, the reflux ratio can be 4:1, 5:1, 6:1, 7:1, 8:1, or 9:1, and the pressure can be -90 kPa, -80 kPa, -70 kPa, -60 kPa, -50 kPa, -40 kPa, -30 kPa, or -20 kPa.

[0036] The heavy component removal process removes high-boiling components such as acetal, triethoxymethoxysilane, triethoxymethylsilane, and ether complexing agents. The electronic-grade DEMS product is output from the top of the tower and stored in a stainless steel storage tank via pipeline.

[0037] In this invention, the apparatus used in the method preferably includes a reactor for carrying out the chelation reaction; the top of the reactor is preferably provided with multiple reserved ports, including a nitrogen port, a thermometer port, a pressure gauge port, a sight glass port and a solid feeder port; The stirring device in the reactor is preferably made of 316L material; A filtration device connected to the reactor; A light-light residue removal tower connected to the filtration device; a mechanical pump is preferably provided between the filtration device and the light-light residue removal tower; and an ether complexing agent / azeotropic agent feed pump connected to the dehydrogenation tower. The heavy removal tower connected to the light removal tower.

[0038] The material of the heavy removal tower and the light removal tower is preferably 316L, and the pressure range is preferably -0.1~0.8Mpa. The heavy removal tower and the light removal tower are preferably also equipped with a high and low temperature integrated unit, a condensation device and a vacuum device. The heavy removal tower and the light removal tower preferably include a plate tower, a packed tower or a plate-packed composite tower.

[0039] The following detailed description of the method for removing impurities from diethoxymethylsilane provided by the present invention, with reference to specific embodiments, is not intended to limit the scope of protection of the present invention.

[0040] Figure 1 This is an example of an apparatus used to remove impurities from diethoxymethylsilane.

[0041] The crude DEMS in the examples and comparative examples contained 95% DEMS by mass. Impurities included methanol, ethanol, chlorosilane, ethoxymethylsilane, triethoxymethylsilane, acetal, triethoxymethoxysilane, Li, Na, Mg, Al, K, Ca, Zn, Fe, Cu, Ag, V, Ti, Mn, Co, Cr, Pb, Ga and other metal compounds and B, P, As and other non-metal compounds.

[0042] Example 1 First, DTPA was added to crude DEMS for a chelation reaction, with a mass ratio of crude DEMS to DTPA of 1000:1. After stirring at room temperature for 6 hours, the mixture was filtered through a small filter (micropore diameter 200 nm, filtration precision 100 nm). Some metal impurities were adsorbed by DTPA, achieving a metal impurity removal rate of 85%. Subsequently, the filtrate was pumped into a light-light removal tower using a mechanical pump. Simultaneously, a mixture of silane and n-hexane was added to the bottom of the light-light removal tower using a mechanical pump, with a mass ratio of crude DEMS to silane of 5000:1 and a mass ratio of crude DEMS to n-hexane of 500:1. The pressure in the light-light removal tower was maintained at -80 kPa, the bottom temperature at 60°C, the reflux ratio at 4:1, and the cold water temperature at -5°C. Except for 10% low-boiling components, low-boiling components such as ethanol, chlorosilanes, and ethoxymethylsilanes were carried out. Some of the low-boiling impurities were captured by pore ethers, and some were carried out by the low-boiling components. The removal rate of low-boiling components and low-boiling impurities reached 99.99%. Finally, the product from the bottom of the light component removal tower was pumped into the heavy component removal tower by a mechanical pump. The pressure in the heavy component removal tower was maintained at -80 kPa, the bottom temperature at 60°C, the reflux ratio at 6:1, and the cold water temperature at -5°C. The product was collected from the top of the tower. The removal rate of heavy components reached 100%, and the removal rate of high-boiling impurities reached 99.99%. The mass fraction of DEMS in the obtained DEMS product was 99.999%, the impurity content of the DEMS product was 0.532 ppb, the mass fraction of ethanol was 0.001%, and the chloride ion content was less than 0.23 ppm, which met the process requirements.

[0043] Example 2 First, citric acid was added to crude DEMS for a chelation reaction, with a mass ratio of crude DEMS to citric acid of 1000:1. After stirring at room temperature for 6 hours, the mixture was filtered through a small filter (micropore diameter 200 nm, filtration precision 100 nm). Some metal impurities were adsorbed by the citric acid, achieving a metal impurity removal rate of 80%. Subsequently, the filtrate was pumped into the light impurity removal tower via a mechanical pump. Simultaneously, a mixture of anisole and n-pentane was added to the bottom of the light impurity removal tower via a mechanical pump, with a mass ratio of crude DEMS to anisole of 5000:1 and a mass ratio of crude DEMS to n-pentane of 500:1. The pressure in the light impurity removal tower was maintained at -80 kPa, the bottom temperature at 60 °C, the reflux ratio at 4:1, and the cold water temperature at -5 °C. After 10% low-boiling point, low-boiling components such as ethanol, chlorosilane, and ethoxymethylsilane are carried out. Some of the low-boiling impurities are captured by anisole, and some are carried out by the low-boiling components. The removal rate of low-boiling components and low-boiling impurities reaches 99.95%. The product from the bottom of the light component removal tower is pumped into the heavy component removal tower by a mechanical pump. The pressure in the heavy component removal tower is maintained at -80 kPa, the bottom temperature is maintained at 60°C, the reflux ratio is 6:1, and the cold water temperature is -5°C. The product is collected from the top of the tower. The removal rate of heavy components reaches 100%, and the removal rate of high-boiling impurities reaches 99.98%. The mass fraction of DEMS in the obtained DEMS product is 99.996%, the impurity content of the DEMS product is 0.889 ppb, the ethanol content is 0.004%, and the chloride ion content is less than 0.34 ppm, which meets the process requirements.

[0044] Example 3 First, HEDTA was added to crude DEMS for a chelation reaction, with a mass ratio of crude DEMS to HEDTA of 1000:1. After stirring at room temperature for 6 hours, the mixture was filtered through a small filter (micropore diameter of 200 nm, filtration precision of 100 nm). Some metal impurities were adsorbed by HEDTA, achieving a metal impurity removal rate of 90%. Subsequently, the filtrate was pumped into the light-light removal tower via a mechanical pump. Simultaneously, a mixture of diphenyl ether and n-hexane was added to the bottom of the light-light removal tower via a mechanical pump, with a mass ratio of crude DEMS to diphenyl ether of 5000:1 and a mass ratio of crude DEMS to n-hexane of 500:1. The pressure in the light-light removal tower was maintained at -80 kPa, the bottom temperature at 60 °C, the reflux ratio at 4:1, and the cold water temperature at -5 °C. After removing 10% of low-boiling components at ℃, low-boiling components such as ethanol, chlorosilane, and ethoxymethylsilane were carried out. Some of the low-boiling impurities were captured by anisole, and some were carried out by the low-boiling components. The removal rate of low-boiling components and low-boiling impurities reached 99.98%. The product from the bottom of the light component removal tower was pumped into the heavy component removal tower by a mechanical pump. The pressure in the heavy component removal tower was maintained at -80 kPa, the bottom temperature was maintained at 60℃, the reflux ratio was 6:1, and the cold water temperature was -5℃. The product was collected from the top of the tower. The removal rate of heavy components reached 100%, and the removal rate of high-boiling impurities reached 99.99%. The mass fraction of DEMS in the obtained DEMS was 99.999%, the impurity content of the DEMS product was 0.486 ppb, the mass fraction of ethanol was 0.001%, and the chloride ion content was less than 0.3 ppm, which met the process requirements.

[0045] Comparative Example 1 The reaction was carried out without the participation of metal chelating agents, azeotropic agents, or complexing agents. The product was purified by atmospheric distillation (boiler temperature 100℃, reflux ratio 6:1, cold water temperature -5℃). The DEMS purity reached 99%, the impurity was 753.8 ppb, the ethanol mass fraction was 0.58%, the mass fraction of other components was 0.42%, and the chloride ion content reached 36 ppm. The composition and impurities did not meet the process requirements.

[0046] Comparative Example 2 Without the participation of metal chelating agents, azeotropic agents, or complexing agents in the reaction, purification was carried out solely through vacuum distillation at -80 kPa (boiler temperature 60°C, reflux ratio 6:1, and cold water temperature -5°C). The DEMS purity reached 99.5%, with impurities of 685.4 ppb, an ethanol mass fraction of 0.35%, other component mass fractions of 0.25%, and chloride ion content of 28 ppm. The composition and impurities did not meet the process requirements.

[0047] Table 1. Changes in DEMS composition and impurities under different process conditions.

[0048] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for removing impurities from diethoxymethylsilane, characterized in that, Includes the following steps: Diethoxymethylsilane was mixed with a metal chelating agent and then subjected to a chelation reaction to obtain a reaction solution; The reaction solution, azeotropic agent and ether complexing agent are mixed and then subjected to complexation-azeotropic-reduced pressure distillation to remove light components and obtain the reaction system. Remove heavy components from the reaction system.

2. The method according to claim 1, characterized in that, The impurities of the diethoxymethylsilane include, but are not limited to, methanol, ethanol, chlorosilane, ethoxymethylsilane, triethoxymethylsilane, acetal, triethoxymethoxysilane, metal compounds and non-metal compounds; The metallic elements in the metal compound include one or more of Li, Na, Mg, Al, K, Ca, Zn, Fe, Cu, Ag, V, Ti, Mn, Co, Cr, Pb, and Ga; The nonmetallic elements in the nonmetallic compound include one or more of As, B, and P.

3. The method according to claim 1, characterized in that, The metal chelating agent includes one or more of the following: diethylenetriaminepentaacetic acid, hypozinotriacetic acid, hydroxyethylethylenediaminetriacetic acid, ethylene glycol diethyl ether diaminetetraacetic acid, tetrasodium glutamate diacetate, tetrasodium iminodisuccinate, trisodium methylglycine diacetate, hydroxyethylenediphosphonic acid, sodium gluconate, citric acid, and ethylenediaminedisuccinate.

4. The method according to claim 1 or 3, characterized in that, The mass ratio of diethoxymethylsilane to metal chelating agent is 500~2000:

1.

5. The method according to claim 1, characterized in that, The chelation reaction was carried out at a temperature of 25-40°C for 6 hours. The chelation reaction was carried out under stirring conditions; The chelation reaction further includes: filtering the system obtained from the chelation reaction to obtain the reaction solution; The filtration device used in the filtration process has a micropore diameter of 100~500nm and a filtration accuracy of less than 200nm.

6. The method according to claim 1, characterized in that, The azeotropic agent includes one or more of n-hexane, pentane, isohexane, 3-methylpentane, neohexane, and n-pentane.

7. The method according to claim 1 or 6, characterized in that, The mass ratio of diethoxymethylsilane to azeotropic agent is 500~1000:

1.

8. The method according to claim 1, characterized in that, The ether complexing agents include one or more of p-bromoanisole, diphenyl ether, crown ether, azacrown ether, crypt ether, spherical ether, anisole, p-methylanisole, anethole, benzyl ethyl ether, benzyl phenyl ether, benzofuran, and dibenzofuran.

9. The method according to claim 1 or 8, characterized in that, The mass ratio of diethoxymethylsilane to ether complexing agent is 3000~8000:

1.

10. The method according to claim 1, characterized in that, The complexation-azeotropic-reduced pressure distillation is carried out in a light-light-removal column; The temperature of the condensate at the top of the light-weight removal tower is -20~5℃; the temperature at the bottom of the tower is 60~90℃. The reflux ratio of the complexation-azeotropic-reduced pressure distillation is 3~8:1, and the pressure is -95~-20kPa; The temperature of the condensate at the top of the heavy component removal tower is -20~5℃, and the temperature at the bottom of the tower is 60~90℃. The reflux ratio for the removal of the heavy components is 3~10:1, and the pressure is -95~-20Kpa.

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