Method for synthesizing and purifying electronic-grade tetramethyldisiloxane

Abstract

The invention discloses a synthesis and purification method of electronic-grade tetramethyldisiloxane, which comprises the following steps: depolymerizing by using TMCTS, a methyl Grignard reagent CH3MgX and xylene as reaction raw materials during synthesis, and hydrolyzing by using a hydrochloric acid aqueous solution with solute mass fraction of 10%; in the purification process, a water filtering molecular sieve, a microporous quartz filter and a quartz cation exchange column are adopted for early-stage purification, desolventizing treatment is carried out through a quartz desolventizing tower, and finally rectification is carried out through a quartz rectifying tower by adopting a method that the process parameters are total reflux for 8-12 hours, fractions are collected from the tower top and the temperature is 72 DEG C; and finally, packaging in a quartz container in a vacuum cavity. The method has the characteristics of Grignard reagent substitution and depolymerization, low reaction temperature, high yield, low cost and simple and easy-to-separate impurity components.

Description

Technical Field

[0001] The present invention relates to a high-purity semiconductor dopant, and particularly to a method for synthesizing and purifying electronic-grade tetramethyldisiloxane. Background Art

[0002] Doping of semiconductors is to improve the electrical properties of semiconductor devices, and many electrical characteristics of semiconductors are related to the impurity concentration of doping.

[0003] In the prior art, there are few synthesis methods for electronic-grade tetramethyldisiloxane. There is only one method that can be consulted, and it has very obvious inherent defects: after hydrolysis and alcoholysis of dimethylchlorosilane, rectification and purification are carried out. At present, there are obvious problems of low yield, many by-products, and difficulty in separating impurities during post-treatment.

[0004] In the current prior art, there is no related technology to solve the above problems. At present, a method for synthesizing and purifying electronic-grade tetramethyldisiloxane with Grignard reagent substitution and depolymerization, low reaction temperature, high yield, low cost, and simple impurity components easy to separate is needed. Summary of the Invention

[0005] The present invention aims to provide a method for synthesizing and purifying electronic-grade tetramethyldisiloxane with Grignard reagent substitution and depolymerization, low reaction temperature, high yield, low cost, and simple impurity components easy to separate.

[0006] To achieve the above object, the present invention adopts the following technical solutions: A method for synthesizing and purifying electronic-grade tetramethyldisiloxane, and this process method includes the following stages: S1: Raw material preparation ① Raw material preparation: Prepare sufficient TMCTS, methyl Grignard reagent CH3MgX, sufficient xylene, sufficient hydrochloric acid aqueous solution with a solute mass fraction of 10%, and sufficient nitrogen; ② Tooling and equipment preparation: Prepare a low-temperature constant-temperature reaction device, prepare a filter molecular sieve, a microporous quartz filter with a filtration aperture of 0.01 μm, a quartz cation exchange column, a quartz solvent removal tower with a theoretical plate number of 10 - 100, a quartz rectification column, a vacuum chamber with a vacuum degree of 1×10 -4 Pa - 1×10 -3 Pa, and a quartz encapsulation container; all transmission pipelines of the equipment are made of polytetrafluoroethylene pipes; S2: Synthesis of tetramethyldisiloxane ① Use the xylene prepared in step ① of stage S1 as a solvent to dilute the methyl Grignard reagent CH3MgX, and the mass ratio of the two is (20 - 35):1, and put it into the low-temperature constant-temperature reaction device prepared in step ② of stage S1; ②Adjust the working temperature of the reaction area of the low-temperature constant-temperature reaction device to maintain the temperature range of 1°C to 7°C. Immediately mix TMCTS and xylene evenly according to the molar ratio, and then slowly add them to the low-temperature constant-temperature reaction device. During the addition process, control the stirring rate at 15 rpm to 30 rpm and the reaction time at 80 min to 100 min to complete depolymerization. ③Slowly drop dilute hydrochloric acid into the reaction solution after depolymerization in step ②, control the working temperature of the reaction area to maintain the temperature range of 1°C to 10°C, control the stirring rate at 15 rpm to 30 rpm, and react for 55 min to 70 min to complete hydrolysis. ④Let the reaction mixture after hydrolysis in step ③ stand until it is completely stratified, and separate the upper liquid in the standing state to obtain crude tetramethyldisiloxane. S3: Purification of tetramethyldisiloxane ①Pretreatment before purification: Use the filtered molecular sieve prepared in step ② of stage S1 to filter the crude tetramethyldisiloxane obtained in step ④ of stage S2 to remove water, and obtain dehydrated tetramethyldisiloxane. Immediately pass the dehydrated tetramethyldisiloxane through the microporous quartz filter prepared in step ② of stage S1 for fine filtration to obtain fine-filtered tetramethyldisiloxane. Then, perform ion exchange on the fine-filtered tetramethyldisiloxane using a quartz cation exchange column to obtain pretreated tetramethyldisiloxane. ②Desolventization treatment: Add the pretreated tetramethyldisiloxane obtained in step ① to the quartz desolventization tower prepared in step ② of stage S1. The desolventization process parameters are that the top fraction is received at 66°C to 78°C to separate the solvent and obtain desolventized tetramethyldisiloxane. ③Rectification: Add the desolventized tetramethyldisiloxane obtained in step ② to the quartz rectification tower prepared in step ② of stage S1. The rectification process parameters are full reflux for 8 to 12 hours, and collect the fraction product with a boiling point of 72°C. Rectification obtains rectified tetramethyldisiloxane. S4: Encapsulation ①Encapsulate the rectified tetramethyldisiloxane obtained in step ② of stage S3 in the vacuum chamber prepared in step ② of stage S1 using the quartz encapsulation container prepared in step ② of stage S1. After encapsulation and sealing, obtain the required electronic-grade tetramethyldisiloxane.

[0007] Compared with the prior art, the present invention has the following advantages due to the adoption of the above technical solutions: (1) The method of the present invention is different from the method for synthesizing electronic-grade tetramethyldisiloxane in the prior art, that is, dimethylchlorosilane is hydrolyzed and alcoholyzed and then purified by rectification. The method in the prior art currently has obvious problems of low yield, more by-products, and difficulty in separating impurities during post-treatment. The present invention uses methyl Grignard reagent to replace and depolymerize, and then adds dilute hydrochloric acid for hydrolysis. The reaction reliability, stability and controllability are all better than those of the hydrolysis and alcoholysis of dimethylchlorosilane in the prior art. In addition, the reaction temperature of the present invention is low, only normal temperature or lower than normal temperature is required during the reaction stage, with good safety and low cost, which is conducive to industrial application; the yield of the present invention is at least 80%, which is higher than that of the prior art; most of the impurities in the present invention are water, organic solvents, etc., which can be simply separated by rectification or multiple distillations, and the product purity is high.

[0008] Therefore, the present invention has the characteristics of Grignard reagent substitution and depolymerization, low reaction temperature, high yield, low cost, and simple impurity components and easy separation. Specific embodiments Examples

[0009] A method for synthesizing and purifying electronic-grade tetramethyldisiloxane, which process method includes the following stages: S1: Raw material preparation ① Raw material preparation: Prepare sufficient TMCTS, methyl Grignard reagent CH3MgX, sufficient xylene, sufficient hydrochloric acid aqueous solution with a solute mass fraction of 10%, and sufficient nitrogen; ② Tooling and equipment preparation: Prepare a low-temperature constant-temperature reaction device, prepare a filter molecular sieve, a microporous quartz filter with a filtration pore diameter of 0.01μm, a quartz cation exchange column, a quartz desolventization tower with a theoretical plate number of 10-100, a quartz rectification tower, a vacuum chamber with a vacuum degree of 1×10 -4 Pa~1×10 -3 Pa, and a quartz encapsulation container; all the transmission pipelines of the equipment are made of polytetrafluoroethylene pipes; S2: Synthesis of tetramethyldisiloxane ① Use the xylene prepared in step ① of stage S1 as a solvent to dilute the methyl Grignard reagent CH3MgX, and the mass ratio of the two is (20-35):1, and put it into the low-temperature constant-temperature reaction device prepared in step ② of stage S1; ② Adjust the working temperature of the reaction area of the low-temperature constant-temperature reaction device to keep the temperature range at 1°C~7°C, and then mix TMCTS and xylene evenly in a molar ratio, and then slowly add them to the low-temperature constant-temperature reaction device; control the stirring rate at 15rpm~30rpm during the addition process, and the reaction time is 80min~100min to complete the depolymerization; ③ Slowly drop dilute hydrochloric acid into the reaction solution that has completed depolymerization in step ②, control the working temperature of the reaction area, maintain the temperature range of 1°C to 10°C, control the stirring rate at 15 rpm to 30 rpm, and complete hydrolysis after reacting for 55 min to 70 min; ④ Let the reaction mixture that has completed hydrolysis in step ③ stand until it is completely stratified, and separate the upper liquid therein in a static state to obtain crude tetramethyldisiloxane; S3: Purification of tetramethyldisiloxane ① Pretreatment before purification: Use the filtered molecular sieve prepared in step ② of stage S1 to filter the crude tetramethyldisiloxane obtained in step ④ of stage S2 to remove water. After filtering out the water, obtain dehydrated tetramethyldisiloxane; Immediately pass the dehydrated tetramethyldisiloxane through the microporous quartz filter prepared in step ② of stage S1 for fine filtration to obtain fine-filtered tetramethyldisiloxane; Then perform ion exchange on the fine-filtered tetramethyldisiloxane using a quartz cation exchange column to obtain pretreated tetramethyldisiloxane; ② Desolventization treatment: Add the pretreated tetramethyldisiloxane obtained in step ① to the quartz desolventization tower prepared in step ② of stage S1. The desolventization process parameters are that the distillate received at the top of the tower is 66°C to 78°C, separate the solvent, and obtain desolventized tetramethyldisiloxane; ③ Rectification: Add the desolventized tetramethyldisiloxane obtained in step ② to the quartz rectification tower prepared in step ② of stage S1. The rectification process parameters are total reflux for 8 to 12 hours, and collect the fraction product with a boiling point of 72°C; Rectification obtains rectified tetramethyldisiloxane; S4: Encapsulation ① Encapsulate the rectified tetramethyldisiloxane obtained in step ② of stage S3 in the vacuum chamber prepared in step ② of stage S1 using the quartz encapsulation container prepared in step ② of stage S1. After encapsulation and sealing, obtain the required electronic-grade tetramethyldisiloxane.

[0010] The electronic-grade tetramethyldisiloxane obtained according to this embodiment has the characteristics of Grignard reagent substitution and depolymerization, low reaction temperature, high yield, low cost, and simple impurity components and easy separation.

[0011] The above description of the disclosed embodiments is only to enable those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art. The general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for synthesizing and purifying electronic grade tetramethyldisiloxane, characterized in that: The process The following phases are included: S1: Raw material preparation ① Raw material preparation: prepare sufficient TMCTS, methyl Grignard reagent CH3MgX, sufficient xylene, sufficient hydrochloric acid aqueous solution with a solute mass fraction of 10%, and sufficient nitrogen; ② Preparation of tools and equipment: low-temperature constant temperature reaction device, water filter molecular sieve, microporous quartz filter with a pore size of 0.01 μm, quartz cation exchange column, quartz desolventizing tower with a theoretical plate number of 10 to 100, quartz distillation tower, vacuum degree 1×10 -4 Pa~1×10 -3 Pa vacuum chamber, quartz packaging container; all equipment transmission pipelines are made of polytetrafluoroethylene tubes; S2: Tetramethyldisiloxane Synthesis ① Use the xylene prepared in step ① of stage S1 as solvent to dilute the methyl Grignard reagent CH3MgX, the mass ratio of the two is (20-35): 1, and put it into the low-temperature constant temperature reaction device prepared in step ② of stage S1; ② Adjust the working temperature of the reaction area of ​​the low-temperature constant temperature reaction device to maintain the temperature range of 1°C~7°C, then mix TMCTS and xylene evenly in molar ratio, and then slowly add them into the low-temperature constant temperature reaction device; during the addition process, control the stirring rate to 15rpm~30rpm, the reaction time to 80min~100min, and complete the depolymerization; ③ Slowly add dilute hydrochloric acid to the reaction solution after depolymerization in step ②, control the working temperature of the reaction area, maintain the temperature range of 1°C~10°C, control the stirring rate to 15rpm~30rpm, and react for 55min~70min to complete the hydrolysis; ④ The reaction mixture after the hydrolysis in step ③ is allowed to stand until the layers are completely separated, and the upper layer of liquid is separated under standing condition to obtain crude tetramethyldisiloxane; S3: Tetramethyldisiloxane purification ① Purification pretreatment: the crude tetramethyldisiloxane obtained in step ④ of step S2 is filtered and dehydrated using the water-filtering molecular sieve prepared in step ② of step S1 to obtain dehydrated tetramethyldisiloxane after filtering out the water; the dehydrated tetramethyldisiloxane is then finely filtered through the microporous quartz filter prepared in step ② of step S1 to obtain finely filtered tetramethyldisiloxane; the finely filtered tetramethyldisiloxane is then ion exchanged using a quartz cation exchange column to obtain pretreated tetramethyldisiloxane; ② Desolventization treatment: the pre-treated tetramethyldisiloxane obtained in step ① is added into the quartz desolventization tower prepared in step ② of stage S1, and the desolventization process parameters are that the top of the tower receives the fraction at 66°C to 78°C, and the solvent is separated to obtain desolventized tetramethyldisiloxane; ③ Distillation: Add the desolventized tetramethyldisiloxane obtained in step ② into the quartz distillation tower prepared in step ② of stage S1, and the distillation process parameters are total reflux for 8 to 12 hours, and collect the fraction product with a boiling point of 72°C; Rectification to obtain rectified tetramethyldisiloxane; S4: Encapsulation ① The distilled tetramethyldisiloxane obtained in step ② of stage S3 is packaged in the vacuum chamber prepared in step ② of stage S1 using the quartz packaging container prepared in step ② of stage S1. After the packaging is completed and sealed, the required electronic grade tetramethyldisiloxane is obtained.