Method for preparing high-purity high-quality hexamethyldisiloxane

Abstract

The invention discloses a method for preparing high-purity high-quality hexamethyldisiloxane. The preparation method comprises the following steps: (1) dropwise adding trimethylsilyl chloride to a hydrolysis reaction kettle to which water and a condensation catalyst are added in advance, and carrying out heating reflux; (2) layering the product into a demixer after hydrolysis reaction is finished, wherein the condensation catalyst is at the lowest layer and can be separated and recycled; concentrated acid water is at the middle layer, chlorine hydride can be recovered by a hydrochloric acid analysis technology; a hydrolysate at the upper layer is washed with water and neutralized to neutral by using a carbonate solution, an oil phase is separated out of the hydrolysate at the upper layer after the hydrolysate at the upper layer is washed with water for a plurality of times; (3) removing water from the oil phase separated in the step (2) by using a water removal agent, stirring and filtering; (4) fractionating and collecting fraction with the temperature of 99-102 DEG C, so as to obtain the hexamethyldisiloxane of which the purity is greater than 99.9% (mass fraction). The preparation method disclosed by the invention has the advantages that the reaction speed is high, the utilization rate of trimethylsilyl chloride is high and the yield and quanlity of hexamethyldisiloxane are high.

Description

technical field [0001] The invention relates to the technical field of organic compound preparation, in particular to a preparation method of high-purity and high-quality hexamethyldisiloxane. Background technique [0002] Hexamethyldisiloxane plays a very important role in the production of silicone products as the primary raw material of silicone downstream products. It can be used as a head-sealing agent in the production of silicone oil, as a raw material for silazane, and as a cleaning agent for silicone rubber, pharmaceuticals, gas chromatography stationary liquid, analytical reagents, water-repellent agents, and medical electronic components. Hexamethyldisiloxane is mainly obtained through hydrolysis and condensation of trimethylmonochlorosilane. However, due to production and separation reasons, it is difficult to achieve 100% purity of hexamethyldisiloxane products, which often contain A small amount of trimethylsilanol and chloride ions: Trimethylsilanol has stron...

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Problems solved by technology

Hexamethyldisiloxane is mainly obtained through hydrolysis and condensation of trimethylmonochlorosilane. However, due to production and separation reasons, it is difficult to achieve 100% purity of hexamethyldisiloxane products, which often contain A small amount of trimethylsilanol and chloride ions: Trimethylsilanol has strong acidity. Due to its purity, when it is used as an end-capping agent, it often leads to some deviations from the expected experimental results; trimethylsilanol A small amount of difficult-to-react impurities contained in chloro-chlorosilane, the reaction conditions required to replace the chlorine in these impurities are relatively harsh, and it needs to be reacted under a catalyst and an appropriate temperature. Its structural chlorine is difficult to be replaced in the ordinary hydrolysis reaction process , the existence of this kind of chlorine will lead to acid reflux in hexamethyldisiloxane products, and the chloride ion content in the product will exceed the standard. If it is used as a cleaning agent, it will often cause corrosion of the equipment and affect the service life of the equipment

However, the oil-containing solid chloride produced in the preparation process is difficult to recover and purify, and a relatively large amount of carbonate is required to achieve a high utilization rate of trimethylchlorosilane, which increases the production cost in a disguised form

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