Method for synthesizing 1,1,1,3,5,5,5-heptamethyltrisiloxane by continuous catalysis of solid phase catalyst

Abstract

The invention relates to a method for synthesizing 1,1,1,3,5,5,5-heptamethyltrisiloxane by continuous catalysis of a solid phase catalyst. Hexamethyldisiloxane and straight chain methyl hydrogen polysiloxane in a molar ratio of 3:1-2:1 are taken as raw materials, strongly acidic ion exchange resin is taken as the solid phase catalyst, the reaction temperature is 40 to 80 DEG C, a fixed bed reactor is adopted, the raw materials pass through the reactor filled with the ion exchange resin at a certain flow rate, the retention period is 5 to 10 hours, the conversion rate of the raw materials is ensured by the retention period of the reaction through controlling the flow rate of the reaction product, the continuous reaction production is realized, and the reaction product is subjected to low fraction and high fraction removal rectification to form the 1,1,1,3,5,5,5-heptamethyltrisiloxane product with the purity of over 99 percent. The method has the advantages of readily available raw materials, no three-waste emission, simple process, continuous production, high-efficiency and stable reaction, simple separation, recyclable catalyst, conversion per pass of the raw material straight chain methyl hydrogen polysiloxane of over 32 percent, good product quality and low production cost.

Description

Technical field [0001] The invention relates to a method and process for continuously catalyzing and synthesizing 1,1,1,3,5,5,5-heptamethyltrisiloxane by using a solid phase catalyst. Background technique [0002] 1,1,1,3,5,5,5-Heptamethyltrisiloxane (MDHM) is an important organosilicon intermediate. Because it contains active silicon-hydrogen bonds, it is used to synthesize polyether and alkyl Modified trisiloxane is the basic raw material and can be widely used in pesticide additives, coating additives and daily chemicals, etc. However, the existing synthetic processes generally have disadvantages such as low yield and complex by-products. Therefore, The improvement of the synthesis process of MDHM and the increase of yield are of great significance. [0003] Patent GB0632954 mentions the use of hexamethyldisiloxane (MM) and methylhydrodichlorosilane (MeSiHC12) hydrolysate through concentrated sulfuric acid for catalytic equilibrium of MDHM method, and the trimethylchlorosilane ...

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Problems solved by technology

The above methods have problems such as long reaction time or difficult separation, chlorine-containing raw materials pollute the environment, and the yield is not too high

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