Silicon tetrachloride can be prepared by passing dry chlorine over an intimate mixture of silica and carbon by heating to 1675 K in a porcelain tube
SiO2 + 2C + 2Cl2 → SiCl4 + 2CO
On commercial scale, reaction of silicon with hydrogen chloride gas occurs above 600 K
Si + 4HCl → SiCl4 + 2H2
Silicon tetrachloride is a colourless fuming liquid and it freezes at -70 ⁰C
In moist air, silicon tetrachloride is hydrolysed with water to give silica and hydrochloric acid.
SiCl4 + 4H2O → 4HCl + Si(OH)4
When silicon tetrachloride is hydrolysed with moist ether, linear perchloro siloxanes are formed [Cl-(Si Cl2O)nSiCl3 where n=1-6.
The chloride ion in silicon tetrachloride can be substituted by nucleophile such as OH, OR, etc.. using suitable reagents. For example, it forms silicic esters with alcohols.
SiCl4 + C2H5OH → 4HCl + Si(OC2H5)4 Tetraethoxy silane
Similarly silicon tetrachloride undergoes ammonialysis to form chlorosilazanes.
· Silicon tetrachloride is used in the production of semiconducting silicon.
· It is used as a starting material in the synthesis of silica gel, silicic esters, a binder for ceramic materials.
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