The invention relates to a method for cleaving silicon-silicon bindings and/or silicon-chlorine bindings in monosilanes, polysilanes, and/or oligosilanes. According to the invention, the monosilane, polysilane, and/or oligosilane is dissolved or suspended in an ether or in an ether-hydrochloric acid solution. Said method is used for example for preparing halogenated oligosilanes from halogenated polysilanes and for preparing siloxanes from organochlorosilanes and chlorinated monosilanes. Said method is particularly simple to carry out and as a result is economical.

Chlorosilanes of the general formula H.sub.nSiCl.sub.4-n and/or H.sub.mCl.sub.6-mSi.sub.2, where n=1-4 and m=0-4, are produced in a fluidized bed reactor by reaction of a hydrogen chloride-containing reaction gas with a silicon contact mass granulation mixture composed of a coarse grain fraction and a fine grain fraction, wherein the average particle size of the fine grain fraction d.sub.50,fine is smaller than the average particle size of the coarse grain fraction d.sub.50,coarse.

Chlorosilanes of the general formula H.sub.nSiCl.sub.4-n and/or H.sub.mCl.sub.6-mSi.sub.2, where n=1-4 and m=0-4, are produced in a fluidized bed reactor by reaction of a hydrogen chloride-containing reaction gas with a silicon contact mass granulation mixture composed of a coarse grain fraction and a fine grain fraction, wherein the average particle size of the fine grain fraction d.sub.50,fine is smaller than the average particle size of the coarse grain fraction d.sub.50,coarse.

Metallurgical silicon containing impurities of carbon and/or carbon-containing compounds is classified and subsequently used selectively for chlorosilane production. The process comprises the steps of: a) determining the free carbon proportion which reacts with oxygen up to a temperature of 700 C., b) directing metallurgical silicon in which the free carbon proportion is 150 ppmw to a process for producing chlorosilanes and/or directing metallurgical silicon in which the free carbon proportion is >150 ppmw to a process for producing methylchlorosilanes.

As a result of the process, metallurgical silicon having a total carbon content of up to 2500 ppmw can be used for producing chlorosilanes.

Generally unusable or difficultly useable dusts of ultrahigh purity silicon can be used to produce chlorosilanes under reasonable reaction conditions by employing a catalyst containing one or more of Co, Mo, W. The process may be incorporated into an integral plant for the production of polycrystalline silicon.

Chlorosilanes are produced in exalted yield in a fluidized bed process when the reactor hydraulic diameter, Sauter particle diameter, and superficial gas velocity are used to define a parameter space as a function of Reynolds number and Archimedes number.

The content of boron compounds in a composition containing at least one halosilane is reduced by bringing the composition into contact with at least one phenylsilane and removing the at least one halosilane. The invention further relates to the use of phenylsilanes for removing boron compounds from halosilane-containing compositions.

The present disclosure relates to a process for producing chlorosilanes in a fluidized bed reactor by reaction of a hydrogen and silicon tetrachloride-containing reaction gas with a particulate contact mass containing silicon and a catalyst. The chlorosilanes have the general formula H.sub.nSiCl.sub.4-n and/or H.sub.mCl.sub.6-mSi.sub.2. The reactor design is described by an index K1, the constitution of the contact mass is described by an index K2 and the reaction conditions are described by an index K3.

The present disclosure relates to a process for producing chlorosilanes in a fluidized bed reactor by reacting a hydrogen chloride-containing reaction gas with a particulate contact mass containing silicon and optionally a catalyst. The chlorosilanes have the general formula H.sub.nSiCl.sub.4-n and/or H.sub.mCl.sub.6-mSi.sub.2. The reactor design is described by an index K1, the constitution of the contact mass without catalyst is described by an index K2.sub.uncat, the constitution of the contact mass with catalyst is described by an index K2.sub.cat, and the reaction conditions are described by an index K3.

The invention relates to a method for cleaving silicon-silicon bindings and/or silicon-chlorine bindings in monosilanes, polysilanes, and/or oligosilanes. According to the invention, the monosilane, polysilane, and/or oligosilane is dissolved or suspended in an ether or in an ether-hydrochloric acid solution. Said method is used for example for preparing halogenated oligosilanes from halogenated polysilanes and for preparing siloxanes from organochlorosilanes and chlorinated monosilanes. Said method is particularly simple to carry out and as a result is economical.