Tetrachlorosilane

Structural formula
General
Surname	Tetrachlorosilane
other names	Silicon tetrachloride
Molecular formula	SiCl 4
Brief description	pungent smelling, colorless liquid
External identifiers / databases
CAS number 10026-04-7 EC number 233-054-0 ECHA InfoCard 100.030.037 PubChem 24816 ChemSpider 23201 Wikidata Q413709
properties
Molar mass	169.90 g mol −1
Physical state	liquid
density	1.48 g cm −3
Melting point	−70 ° C
boiling point	57 ° C
Vapor pressure	260 h Pa (20 ° C)
solubility	reacts violently with water
Refractive index	1.41156 (25 ° C)
safety instructions
GHS hazard labeling from  Regulation (EC) No. 1272/2008 (CLP) , expanded if necessary danger H and P phrases H: 301 + 331-314-335 EUH: 014 P: 261-280-301 + 310-305 + 351 + 338-310
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions . Refractive index: Na-D line , 20 ° C

Tetrachlorosilane (also silicon tetrachloride , silicon tetrachloride ) is the perchlorinated derivative of monosilane . It is a chemical compound from the group of silicon tetrahalides with the empirical formula SiCl ₄ . It is a colorless, volatile liquid that smokes in moist air and consists of the elements silicon and chlorine .

history

Tetrachlorosilane was first produced by Jöns Jacob Berzelius in 1823 . To do this, it passed chlorine gas over heated silicon or a silica / carbon mixture and isolated the resulting tetrachlorosilane in a cooled receiver.

${\displaystyle \mathrm {Si+2\ Cl_{2}{\xrightarrow {\triangle }}\ SiCl_{4}} }$

${\displaystyle \mathrm {SiO_{2}+\ C\ +\ 2\ Cl_{2}{\xrightarrow {\triangle }}\ SiCl_{4}+\ CO_{2}} }$

Extraction and presentation

Tetrachlorosilane is usually obtained through the chemical reaction of chlorine with hot silicon:

${\displaystyle \mathrm {Si+2\ Cl_{2}\rightarrow SiCl_{4}} }$.

Since further processing into silicon dioxide produces hydrogen chloride , this is also used to save raw materials through the composite:

${\displaystyle \mathrm {Si+4\ HCl\rightarrow SiCl_{4}+2\ H_{2}} }$.

The resulting hydrogen can be used for the production of fumed silica .

properties

Tetrachlorosilane is a very reactive compound. Unlike the corresponding carbon compound carbon tetrachloride , tetrachlorosilane reacts violently with water:

${\displaystyle \mathrm {SiCl_{4}+4\ H_{2}O\rightarrow Si(OH)_{4}+4\ HCl} }$

The hydrolysis of tetrachlorosilane takes place via the intermediate stages SiCl ₃ (OH), SiCl ₂ (OH) ₂ and SiCl (OH) ₃ , which can be isolated at lower temperatures. These intermediates can, as with other silanols , with each other with elimination of water z. B. to dimerize or polymerize to linear compounds of the Si _n O _(n-1) Cl _{(2n + 2) type} , the hydrogen chloride formed accelerating the polymerization. The first intermediate, the trichloromonosilanol, dimerizes analogously to other monosilanols, such as trimethylsilanol , with the formation of hexachlorodisiloxane. In any case, the driving force behind the reaction is the formation of the particularly stable Si – O – Si bond.

Oxidizing agents , acids , alcohols , bases , ketones , aldehydes and the like v. a. also react with silicon tetrachloride. It has a strong corrosive effect and is corrosive to the skin, eyes and lungs.

use

In the purification of silicon , silicon tetrachloride is sometimes used as an intermediate. By reaction with butyl lithium in diethyl ether can tetrabutylsilane be made:

${\displaystyle {\ce {SiCl4{}+4LiC4H9->[\mathrm {Et_{2}O} ][]Si(C4H9)4{}+4LiCl}}}$

Web links

• International Chemical Safety Card (ICSC) for tetrachlorosilanes at the National Institute for Occupational Safety and Health (NIOSH).

Individual evidence

1. ↑ ^{a b c d e f g h} Entry on silicon tetrachloride in the GESTIS material database of the IFA , accessed on February 1, 2016(JavaScript required) .
2. ↑ David R. Lide (Ed.): CRC Handbook of Chemistry and Physics . 90th edition. (Internet version: 2010), CRC Press / Taylor and Francis, Boca Raton, FL, Index of Refraction of Inorganic Liquids, pp. 4-140.
3. ↑ Entry on Silicon tetrachloride in the Classification and Labeling Inventory of the European Chemicals Agency (ECHA), accessed on February 1, 2016. Manufacturers or distributors can expand the harmonized classification and labeling .
4. ↑ Gustav Rauter: About silicon tetrachloride . In: Justus Liebig's Annals of Chemistry . tape 270 , no. 1-2 , 1892, pp. 235-266 , doi : 10.1002 / jlac.18922700114 .
5. ↑ Jons Jacob Berzelius: chlorine pebbles . In: Textbook of Chemistry, 5th edition . tape 1 . Arnold-Verlag, Dresden 1856, p. 325–326 ( Digitale-sammlungen.de ).
6. ↑ Joseph Goubeau , Rudolf Warncke: For the hydrolysis of halides. I. The hydrolysis of silicon tetrachloride . In: Journal of Inorganic and General Chemistry . tape 259 , no. 1-4 , October 1949, pp. 109-120 , doi : 10.1002 / zaac.19492590109 .
7. ^ Stephan Pawlenko: Organosilicon Chemistry. Walter de Gruyter, 1986, ISBN 978-3-11-086238-6 , p. 18 ( limited preview in Google book search).