Trichlorosilane


Trichlorosilane is an inorganic compound with the formula HCl3Si. It is a colourless, volatile liquid. Purified trichlorosilane is the principal precursor to 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

Trichlorosilane is produced by treating powdered metallurgical grade silicon with blowing hydrogen chloride at 300 °C. Hydrogen is also produced, as described in the chemical equation:
Yields of 80-90% can be achieved. The main byproducts are silicon tetrachloride, hexachlorodisilane and dichlorosilane, from which trichlorosilane can be separated by distillation.
It is also produced from silicon tetrachloride:

Applications

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

Ingredient in hydrosilylation

Via hydrosilylation, trichlorosilane is a precursor to other useful organosilicon compounds:
Some useful products of this or similar reactions include octadecyltrichlorosilane, perfluoroctyltrichlorosilane, and perfluorodecyltrichlorosilane. These reagents used in surface science and nanotechnology to form Self-assembled monolayers. Such layers containing fluorine decrease surface energy and reduce sticking. This effect is usually exploited as coating for MEMS and microfabricated stamps for a nanoimprint lithography and in injection molding tools.

Organic synthesis

Trichlorosilane is a reagent in the conversion of benzoic acids to toluene derivatives. In the first step of a two-pot reaction, the carboxylic acid is first converted to the trichlosilylbenzyl compound. In the second step, the benzylic silyl derivative is converted to the toluene derivative with base.