A kind of preparation method of high-purity high-quality hexamethyldisiloxane

Abstract

The invention discloses a method for preparing high-purity and high-quality hexamethyldisiloxane. The preparation method includes the following steps: (1) adding trimethylmonochlorosilane dropwise to the pre-added water and condensation catalyst In the hydrolysis reaction kettle, the temperature is raised to reflux; (2) After the hydrolysis reaction is complete, the product is transferred to the stratifier for stratification. The lowest layer is the condensation catalyst, which can be separated and reused. The middle layer is concentrated acid water, which can be separated by hydrochloric acid. Hydrogen chloride is recovered, the hydrolyzate in the upper layer is washed with water, the carbonate solution is neutralized to neutral, and the oil phase is separated after repeated washing; (3) The oil phase separated in step (2) is dewatered with a water remover , Stir and filter; (4) Fractional distillation, collect the fraction at 99-102°C to obtain hexamethyldisiloxane with a purity greater than 99.9% (mass fraction). The preparation method of the invention has fast reaction speed, high utilization rate of trimethylmonochlorosilane, high yield of hexamethyldisiloxane and superior quality.

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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