Preparation method of hexaetcycletrisiloxane or triethyl trimethylcyclotrisiloxane

Abstract

The invention discloses a preparation method of hexaetcycletrisiloxane or triethyl trimethylcyclotrisiloxane, comprising the following steps: tetraethyl orthosilicate or methyl triethoxysilane and Grignard reagents which are formed by metallic magnesium and alkyl halide carry out Grignard reaction in solvents, hydrolytie polycondensation is carried out to the reaction mixture in diluted acid solution, the solvents are evaporated out by separation and washing and are heated commonly with concentrated sulfuric acid to carry out molecular rearrangement, and then comonomer of diethyl siloxane or the comonomer of methyl ethylsiloxane is obtained by renew neutralization and drying; the comonomer is cracked and rectified under the catalysis of potassium carbonate catalyzers, thereby obtaining the hexaetcycletrisiloxane or the triethyl trimethylcyclotrisiloxane. The method avoids environment pollution caused by chlorine monomers and prevents from using the solvents such as diethyl and the like in a large scale, thereby reducing the technique difficulty and investment scale and realizing industrial production of products easily; in addition, the process is not only simplified, but also thesafety of process operation is improved.

Description

technical field [0001] The invention relates to a preparation method of cyclosiloxane monomer, in particular to a preparation method of hexaethylcyclotrisiloxane or triethyltrimethylcyclotrisiloxane. Background technique [0002] Hexaethylcyclotrisiloxane and triethyltrimethylcyclotrisiloxane, as one of the cyclosiloxanes, are important organosilicon monomers and are used to synthesize organosilicon polymers containing ethyl groups. main ingreadient. The existing cyclosiloxane is mainly synthesized by hydrolysis of the corresponding chlorosilane, and one of the preparation methods of the ethyl chlorine-containing monomer is to synthesize the ethyl chlorosilane monomer by using the Grignard method. Because the raw materials used in this preparation method are chlorine-containing monomers, and chlorine-containing monomers not only have a low flash point, are flammable and explosive, but also must use a large amount of flammable substances such as diethyl ether or tetrahydrofu...

AI Technical Summary

Problems solved by technology

Because the raw materials used in this preparation method are chlorine-containing monomers, and chlorine-containing monomers not only have a low flash point, are flammable and explosive, but also must use a large amount of flammable substances such as diethyl ether or tetrahydrofuran, which are also dangerous goods, in the reaction process. Explosive solvent, therefore, there is higher risk in this preparation method; And, because the water solubility of ether or tetrahydrofuran solvent is big, volatility is strong, therefore, this preparation method also has solvent reprocessing difficulty, consumption is big, increases Production Cost Disadvantages

Chlorine-containing monomers as raw materials and intermediates will also aggravate environmental pollution during the production process

In addition, due to the presence of chlorine-containing monomers, the reaction between alkyl chloride and metal magnesium cannot be carried out. Therefore, the preparation of the Grignard reagent, that is, the preparation of alkyl magnesium chloride and the Grignard reaction must be carried out separately.