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Trichlorosilane

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Trichlorosilane
Names
IUPAC name
trichlorosilane
Other names
silyl trichloride, silicochloroform
Identifiers
3D model (JSmol)
ECHA InfoCard 100.030.026 Edit this at Wikidata
EC Number
  • 233-042-5
RTECS number
  • VV5950000
UN number 1295
  • [H][Si](Cl)(Cl)Cl
Properties
HCl3Si
Molar mass 135.45 g/mol
Appearance colourless liquid
Density 1.342×103 kg/m3
Melting point −126.6 °C
Boiling point 31.8 °C
hydrolysis
Hazards
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 3: Short exposure could cause serious temporary or residual injury. E.g. chlorine gasFlammability 4: Will rapidly or completely vaporize at normal atmospheric pressure and temperature, or is readily dispersed in air and will burn readily. Flash point below 23 °C (73 °F). E.g. propaneInstability 2: Undergoes violent chemical change at elevated temperatures and pressures, reacts violently with water, or may form explosive mixtures with water. E.g. white phosphorusSpecial hazard W: Reacts with water in an unusual or dangerous manner. E.g. sodium, sulfuric acid
3
4
2
Flash point −27 °C
Explosive limits 1.2–90.5%
Related compounds
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Trichlorosilane is a chemical compound containing silicon, hydrogen, and chlorine. At high temperatures, it decomposes to produce silicon, and therefore purified trichlorosilane is the principal source of ultrapure silicon in the semiconductor industry. In water, it rapidly decomposes to produce a silicone polymer while giving off hydrochloric acid. Because of its reactivity and wide availability, it is frequently used in the synthesis of silicon-containing organic compounds.

Production

Industrially, trichlorosilane is produced by blowing hydrogen chloride through a bed of silicon powder at 300°C. There, they combine to make trichlorosilane and hydrogen according to the chemical equation

Si + 3 HCl → HSiCl3 + H2

A properly designed reactor can achieve a yield of 80-90% trichlorosilane. The major byproducts are silicon tetrachloride (chemical formula SiCl4), hexachlorodisilane (Si2Cl6), and dichlorosilane (H2SiCl2), from which trichlorosilane can be separated by distillation.

The reverse process is used in the production of silicon of higher purity.

Application

Trichlorosilane is the basic ingredient used in the production of purified polysilicons.

References