SU435241A1 - METHOD OF OBTAINING TETRAKIS (DIMETHILSILOXY) SILAN - Google Patents

Description

one

The invention relates to a process for the preparation of tetrakis (dimethylsiloxy) silane, a valuable monomer for the production of a variety of organosilicon polymeric materials, in particular polysiloxanes with an ordered structure.

A method of producing compounds of this type by hydrolysis of silicon tetrachloride and dimethylchlorosilane is known. The disadvantages of this method are the complexity of the process, the use of a large excess of deficient dimethylchlorosilane, the formation of a large number of by-products and a low yield of the target product.

In order to eliminate these drawbacks, it has been proposed to use tetramethyldisiloxane or alkoxymethylsilane as organosilicon silicon compounds and to conduct the process in the presence of electrophilic catalysts, for example iron, aluminum, zinc halides.

The interaction of alkoxymethylsilanes or tetramethyldisiloxane with silicon tetrachloride proceeds according to the scheme:

CH5

CHs (HSiOl4Si-RCl

Catalyst

Sicb

Si-OR I

sn. I

Shl

where R is lower alkyl or the group H51 (CH3) 2.

The catalyst is better to take in the amount of 0.5-10 wt.%.

As alkoxysilane, it is desirable to take second-alkoxysilanes with 3-4 carbon atoms in the radical. The interaction with silicon tetrachloride can also be subjected to intermediate formation, i.e., in the reaction of the compound, it can have the formula

ten

HlCHjjjSiOJ S

Volatile products as they form

removed from the reaction.

Example 1. In a flask equipped with an nozzle for adiabatic distillation, connected to a descending cooler, aloge and receiver, zash, ish, chlorine calcium chloride

67.2 g of tetramethyldisiloxane, 17 g of silicon tetrachloride and 0.8 g of anhydrous ferric chloride. The mixture is heated to boiling for 18-48 hours, gradually forming a distillate, icy dimethylchlorosilane.

After termination of the distillation, the reaction mixture is transferred to a distillation apparatus and, at atmospheric pressure, unreacted tetramethyl disiloxane is distilled off to a bottom temperature of 120 ° C. The residue is distilled in vacuum, collecting fractions boiling at atmospheric pressure at 120-185 ° C — a mixture of intermediate products containing 2-4 silicon atoms and a chlorine atom in a molecule, and at 185-195 ° C. Tetrakis (dimethylxyloxy) silane was separated from the last fraction by repeated distillation at 188-150 ° C.

Exit 72% (entered into the reaction tetramethyldisiloxane).

Found,%: SiH 1.224, 1.225; C1 traces.

Si5C8H28O4.

Calculated,%: SiH 1,226.

Example 2. The 120-185 ° C fraction obtained by distilling the reaction mixture of Example 1 is subjected to -interaction under the conditions of Example 1 with a calculated amount of tetramethyldisiloxane taken with an excess of 5-50% of Necessary, in the presence of 1% anhydrous ferric chloride. The yield of tetrakis (dimethylsiloxy) silane is 78%.

Example 3. Under the conditions of Example 1, 118.3 g of isopropoxydimethylsilane are reacted with 34 g of silicon tetrachloride and 1.5 g of anhydrous ferric chloride. It releases 56.2 g (89%) of isopropyl chloride. The yield of tetrakis (dimethylsiloxy) silane is 69%.

Subject invention

Claims (2)

1. A method of producing tetrakis (dimethylsiloxy) silane by reacting tetrachloride silicon with organic silicon compounds, characterized in that, in order to simplify the process and increase the yield of the target product, tetramethyl disiloxap or alkoxydimethylsil is used as organic silicon compounds , such as iron halide salts. 2. A method according to claim 1, characterized in that the catalyst is taken in an amount of 0.5 to 10 wt.%.