Silicon tetrachloride

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Silicon tetrachloride
IUPAC name Silicon tetrachloride
Other names Tetrachlorosilane, silicon (IV) chloride, silicon chloride, UN 1818
Identifiers
CAS number [10026-04-7]
PubChem 24816
EINECS number 233-054-0
SMILES [Si](Cl)(Cl)(Cl)Cl
InChI 1/Cl4Si/c1-5(2,3)4
Properties
Molecular formula SiCl4
Molar mass 169.90 g/mol
Appearance Colourless liquid
Density 1.483 g cm−3
Melting point

−68.74 °C

Boiling point

57.65 °C

Solubility in water decomp.
Solubility Chlorinated solvents
Vapor pressure 25.9 kPa at 20 °C
Structure
Crystal structure Tetrahedral
Coordination
geometry
4
Hazards
MSDS External MSDS
Main hazards Corrosive (C), Harmful (Xn)
R-phrases R14 R20 R22 R34 R36/37/38
Flash point S7 S8 S26
Supplementary data page
Structure and
properties
n, εr, etc.
Thermodynamic
data
Phase behaviour
Solid, liquid, gas
Spectral data UV, IR, NMR, MS
Except where noted otherwise, data are given for
materials in their standard state
(at 25 °C, 100 kPa)

Infobox disclaimer and references

Silicon tetrachloride is the chemical compound with the formula SiCl4. It was prepared by Jöns Jakob Berzelius in 1823.

[edit] Chemistry

This colourless volatile liquid compound is prepared by the treatment of silicon with chlorine:

Si + 2 Cl2 → SiCl4

It reacts readily with water, in contrast with carbon tetrachloride. The differing rates of hydrolysis are attributed to the greater atomic radius of the silicon atom, whereas carbon has a smaller atomic radius so the chlorine atoms effectively shield the carbon from attack. In water, the following reaction occurs:

SiCl4 + 2 H2O → SiO2 + 4 HCl

With methanol and ethanol it reacts to give tetramethyl orthosilicate and tetraethyl orthosilicate:

SiCl4 + 4 ROH → Si(OR)4 + 4 HCl

At higher temperatures homologues of silicon tetrachloride can be prepared by the reaction:

Si + SiCl4 → Si2Cl6 + homologues

[edit] Uses

Silicon tetrachloride is sometimes used as an intermediate in the manufacture of extremely pure silicon, since it has a boiling point convenient for purification by repeated fractional distillation; it can be reduced to silicon by hydrogen gas, or hydrolysed to SiO2 as a precursor for extremely pure synthetic fused silica. Very pure silicon is used in large amounts in the semiconductor industry, and also in the production of photovoltaic cells.

[edit] External links