Translation of "Silicon tetrafluoride" in German

In particular, the boron trifluoride used should contain less than 0.01 percent by volume of silicon tetrafluoride.

The hexafluorosilicate can then be processed further in a simple manner to form pure silicon tetrafluoride.

This pressure is maintained by pumping out the silicon tetrafluoride as it is obtained.

Unlike silicon tetrachloride, silicon tetrafluoride is gaseous at room temperature.

Particular preference is given to using silicon tetrafluoride-free boron trifluoride for the catalyst preparation.

Silicon tetrafluoride-free boron trifluoride is particularly preferably used for the preparation of the catalyst.

Silicon Tetrafluoride, SiF4, is a colourless, poisonous acid gas.

These gases predominantly contain silicon tetrafluoride, but may also contain hexafluorosiloxane, fluorosilicic acids and hydrofluoric acid.

The dried hexafluorosilicates are decomposed thermally to form silicon tetrafluoride and metal fluoride, maintaining a corresponding underpressure.

We have found that this object is achieved, according to the invention, by a process wherein a boron trifluoride catalyst which contains less than 0.3 percent by volume of silicon tetrafluoride is used, and the solvent is recycled not less than twice during the continuous polymerization.

V. Topciev: "Borfluorid und seine Verbindungen als Katalysatoren in der Chemie", VEB-Verlag Berlin, 1962, pages 3-8) is accompanied by the formation of a number of by-products, such as steam, hydrogen, fluoride, sulfur trioxide, sulfur dioxide and silicon tetrafluoride, which constitute foreign constituents in the product.

In the process according to the invention, a boron trifluoride which contains less than 0.3 percent by volume of silicon tetrafluoride is used, and the solvent is recycled not less than twice during the continuous polymerization.

The acid filtrate has yellow phosphorus dispersed in it which in the process of this invention is precipitated without difficulty obviously in view of the fact that hydrolysis products of silicon tetrafluoride which promote the emulsification of phosphorus in the waste water are retained in the filter residue on the centrifugal filter.

The invention relates to a process for producing pure silicon tetrafluoride from gases containing silicon fluorine as obtained, for example, during the wet extraction of raw phosphates or when glass bodies are pickled with a mixture of hydrofluoric and sulfuric acids.

This solution is decomposed at 100° to 110° C. in reactors made of nickel alloys with concentrated sulfuric acid to form silicon tetrafluoride which is volatile under these conditions.

The problem on which the invention is based is to provide a process for producing pure silicon tetrafluoride without the simultaneous formation of byproducts which are hardly capable of being used.

The hexafluosilicate is separated, dried and then decomposed thermally, whereby pure silicon tetrafluoride is obtained and the metal fluoride used is recovered and may be returned to the process.

The process is ecologically useful because it allows for pure silicon tetrafluoride to be obtained from waste gases, all necessary adjuvants being conducted in a cyclic process.

The present invention relates to a process for producing silane, SiH4, by reacting silicon tetrafluoride, SiF4, with magnesium hydride, MgH2.

Examples are: silicon tetrachloride, silicon tetrafluoride, organosilanes, e.g. tetramethylsilane, trimethylchlorosilane, dimethyldichlorosilane, methyltrichlorosilane, particularly however, silicon tetrachloride.

A process for producing silane, whereby silicon tetrafluoride is reacted with magnesium hydride in a melt of alkali or alkaline earth halides under a hydrogen partial pressure which is greater than the dissociation pressure of the magnesium hydride at the temperature of the melt.

The problem on which the invention is based is to provide a process for producing pure silane from the raw materials silicon tetrafluoride and magnesium hydride, which are available on an industrial scale.

Moreover, it is known that a portion of these polymers can be reduced by additives (inhibitors), such as, mineral acids, acetyl or benzoyl chloride, silicon tetrachloride, or sulfuryl chloride (German PS 700,218), or also by boron trifluoride, silicon tetrafluoride, tin(II) chloride, chloroacetic acid or p-toluene-sulfonic acid in the dimerization in a solvent (German PS 1,240,847).