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Preparation method and application of low-cost liquid polycarbosilane

A polycarbosilane, low-cost technology, applied in the field of preparation of low-cost liquid polycarbosilane, can solve the problems of inability to target products, unfavorable large-scale production, and high requirements for experimental operations, so as to facilitate large-scale production and popularization and application , avoid solvent bumping, improve the effect of reaction efficiency

Active Publication Date: 2022-02-01
AEROSPACE INST OF ADVANCED MATERIALS & PROCESSING TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Although the reducing agent has a strong reducing ability, it can complete many reduction reactions at a lower temperature without a catalyst, and is the most commonly used reducing agent, but its price is expensive, the experimental operation requirements are high, and the production cost is high; Usually need to adopt the ether solvent of low boiling point in the reaction process, so easy to bump in the reaction process, loss is bigger, is unfavorable for large-scale production
NaBH 4 , LiH, NaH, CaH 2 , MgH 2 Reductants such as reductants have lower cost and higher safety, but their reducing ability is weak, and they need special processes such as catalysts or ball milling at higher temperatures to complete the reduction reaction with higher yields, and there are still areas of application. Narrow, poor selectivity, and even unable to target the target product, etc.
Currently, for the preparation of liquid polycarbosilanes, NaBH has not been used 4 , LiH, NaH, CaH 2 , MgH 2 Reports prepared by other reducing agents

Method used

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  • Preparation method and application of low-cost liquid polycarbosilane
  • Preparation method and application of low-cost liquid polycarbosilane

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preparation example Construction

[0026] As mentioned above, the present invention provides a kind of preparation method of low-cost liquid polycarbosilane in the first aspect, it is characterized in that, described method comprises the steps:

[0027] (1) Add the first high-boiling point organic solvent to the magnesium chips, and then add dropwise the first mixed solution comprising halomethylalkoxysilane and the second high-boiling point organic solvent under the condition of heating and stirring. reaction;

[0028] (2) under the condition of heating and stirring, add dropwise the second mixed solution comprising unsaturated halogenated alkanes and the third high-boiling point organic solvent to the first reaction liquid obtained by reacting in step (1) to react;

[0029] (3) adding a reducing agent system to the second reaction solution obtained by the reaction in step (2), and reacting under ultrasonic assistance and stirring;

[0030] (4) adding the reaction solution obtained from the reaction in step (...

Embodiment 1

[0066] Under the protection of nitrogen, add 2 mol of magnesium chips and 4 mol of diethylene glycol dimethyl ether into the reaction kettle equipped with constant pressure dropping funnel, condenser and stirring device in sequence, stir evenly, add 3.2 mol of chloromethyl formazan The first mixed solution of oxydichlorosilane, 16mol chloromethyldimethoxychlorosilane and 0.9mol chloromethyltrimethoxysilane mixture and 2mol diglyme, the temperature is kept at 40 ° C, dropwise After the end, the reaction was continued for 1 hour; then the second mixed solution containing 15 mol vinyl chloride and 4 mol diethylene glycol dimethyl ether was added dropwise, and the temperature was maintained at 60 ° C. After the dropwise addition, the reaction was continued for 1 hour; then 1.4 mol lithium hydride and 0.14mol lithium borohydride, ultrasonic power 100W, stirring rate 100rpm, and maintain the reaction temperature at 50°C for 1 hour; finally, under full stirring, the above reaction sol...

Embodiment 2

[0069] Under the protection of nitrogen, add 2 mol of magnesium chips and 0.2 mol of diethylene glycol dibutyl ether to the reaction kettle equipped with a constant pressure dropping funnel, condenser and stirring device in sequence, stir evenly, dropwise add 0.68 mol of chloromethyl The first mixed solution of ethoxydichlorosilane, 3mol chloromethyldiethoxychlorosilane, 0.27mol chloromethyltriethoxysilane mixture and 0.5mol diethylene glycol dibutyl ether, the temperature is kept at 60°C , continue the reaction for 5 hours after the dropwise addition; then dropwise add the second mixed solution comprising 15mol ethynyl chloride and 0.3mol diethylene glycol dibutyl ether, keep the temperature at 60°C, continue the reaction for 3 hours after the dropwise addition; then Add 1.2mol sodium hydride and 0.08mol lithium borohydride, ultrasonic power 800W, stirring rate 500rpm, maintain the reaction temperature 70°C for 12 hours; finally, under full stirring, add the above reaction sol...

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Abstract

The invention relates to a preparation method and application of low-cost liquid polycarbosilane. Halogenated methyl alkoxy silane and unsaturated halogenated alkane are used as reaction raw materials, a Grignard coupling reaction is performed to obtain a polycarbosilane intermediate, a low-cost reducing agent is added, a reduction reaction is performed to obtain hydrogenated polycarbosilane, and after the reaction is finished, a neutralization reaction and acid liquor washing are performed to obtain liquid polycarbosilane. According to the method disclosed by the invention, expensive lithium aluminum hydride is replaced by reducing agents such as lithium hydride which is low in cost and easy to obtain, so that the cost can be greatly reduced, and the operation safety is also improved; in addition, a high-boiling-point solvent is adopted to replace a traditional volatile ether solvent, solvent volatilization is reduced, meanwhile, solvent recycling is facilitated, and the preparation cost is further reduced. The method is low in cost, high in safety, high in operability and convenient for large-scale production, popularization and application. The obtained polycarbosilane is good in room-temperature fluidity and high in ceramic yield, can be used for preparing a ceramic-based composite material and can also be used for modifying the composite material.

Description

technical field [0001] The invention relates to a preparation method and application of low-cost liquid polycarbosilane, belonging to the field of ceramic precursors and ceramic matrix composite materials. Background technique [0002] In 1975, Professor Yajima of Tohoku University and his research team obtained polycarbosilane through pyrolytic rearrangement of polydimethylsilane, and successfully prepared SiC ceramic fibers through spinning, non-melting treatment, high-temperature cracking and other steps. A new direction for the preparation of high-performance ceramics by precursor conversion method. After more than 30 years of development, the precursor conversion method has now become the main method for preparing SiC ceramics and their composites. [0003] The preparation of SiC ceramic matrix composites by the precursor conversion method first requires a suitable precursor. Currently commonly used precursors are those with [Si(CH 3 ) HCH 2 ] Structure of polycarbo...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C08G77/60C04B35/571
CPCC08G77/60C04B35/571C04B2235/6562C04B2235/6567
Inventor 贺丽娟刘圆圆李文静张昊赵英民
Owner AEROSPACE INST OF ADVANCED MATERIALS & PROCESSING TECH
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