Method for preparing dimethyl hydrochlorosilane through homogeneous disproportionation reaction

Abstract

The invention relates to a preparation method of dimethyl hydrochlorosilane, and particularly relates to a method for preparing dimethyl hydrochlorosilane through homogeneous disproportionation reaction. The preparation method comprises the steps of adding trimethylchlorosilane, methyl hydrogen dichlorosilane, a composite catalyst and a solvent into a disproportionation reaction kettle according to a ratio, wherein the molar ratio of trimethylchlorosilane to methyl hydrogen dichlorosilane is 1: 0.1 to 1: 10, the adding amount of the solvent is 10%-100% of the mass sum of the trimethylchlorosilane and the methyl hydrogen dichlorosilane, and the adding amount of the composite catalyst is 1%-10% of the mass sum of trimethylchlorosilane and monomethyldichlorosilane; controlling the reaction temperature to be 120-160 DEG C and the reaction pressure to be 0.3-0.8 MPa, conducting a stirring reaction for 1-3 h, obtaining a mixed monomer containing dimethyl hydrochlorosilane, enabling the mixed monomer to be subjected to rectification separation, and obtaining dimethyl hydrochlorosilane with the purity greater than 98%. The reaction efficiency and the selectivity of preparing the dimethyl hydrochlorosilane through the disproportionation reaction are improved, and the generation of by-products is reduced.

Description

technical field [0001] The invention relates to a method for preparing dimethylhydrochlorosilane in the technical field of methylchlorosilane monomer production; in particular, a method for preparing dimethylhydrochlorosilane by homogeneous disproportionation reaction. Background technique [0002] Dimethylhydrochlorosilane is an important chlorosilane monomer, mainly used in the production of tetramethyldihydrosiloxane, tetramethyldivinylsiloxane, and widely used in modified silicone oil, addition silicone In the production process of rubber, it is a very important organosilicon chemical raw material. [0003] At present, the Rochow method is mostly used in China to directly synthesize methylchlorosilane. During the production process, about 0.5%∽1% of dimethylhydrochlorosilane is produced by-product, and dimethylhydrochlorosilane exists in organic silicon low boilers. Therefore, some organosilicon enterprises extract dimethyl hydrochlorosilane from the by-product low boil...

AI Technical Summary

Problems solved by technology

Therefore, some organosilicon enterprises extract dimethyl hydrochlorosilane from the by-product low boilers. The advantage is that the by-product low boilers are cheap, and the disadvantage is that the low boilers have complex components, similar boiling points, and difficult separation. The obtained dimethyl hydrogen Chlorosilane has low purity, large amount of by-products, and cannot be properly disposed of, causing certain pollution to the environment

[0004] Chinese Patent CN97195464.X and U.S. Patent USP6245926 disclose a method for preparing dimethylhydrochlorosilane with trimethylchlorosilane and methylhydrogendichlorosilane as raw materials. The method uses Lewis acids such as aluminum trichloride as catalysts. , in the later stage of the redistribution reaction, it is necessary to add linear or cyclic polydimethylsiloxane as an inhibitor, the content of dimethylhydrochlorosilane in the obtained product is low, and the catalyst cannot be recycled and regenerated, resulting in a certain waste of resources and Environmental issues

The single-pass conversion rate of this reaction is not high, and there are many types of by-products, which are not easy to separate

[0007] In summary, the preparation of dimethylhydrochlorosilane by the catalytic hydrogenation process of dimethyldichlorosilane has the characteristics of low conversion rate per pass and many types of by-products.

And the reaction that adopts aluminum trichloride solid-state catalyst to prepare dimethyl hydrochlorosilane, mostly is heterogeneous phase reaction such as gas-solid phase, liquid-solid phase reaction, exists reaction temperature height, by-product is many, primary conversion rate is low, reaction process Requires multiple fractional distillation and refining