Silicon tetrafluoride or Tetrafluorosilane is the chemical compound

Chemical compound

A chemical compound is a pure chemical substance consisting of two or more different chemical elements that can be separated into simpler substances by chemical reactions. Chemical compounds have a unique and defined chemical structure; they consist of a fixed ratio of atoms that are held together...

 with the formula Si

Silicon

Silicon is a chemical element with the symbol Si and atomic number 14. A tetravalent metalloid, it is less reactive than its chemical analog carbon, the nonmetal directly above it in the periodic table, but more reactive than germanium, the metalloid directly below it in the table...

F

Fluorine

Fluorine is the chemical element with atomic number 9, represented by the symbol F. It is the lightest element of the halogen column of the periodic table and has a single stable isotope, fluorine-19. At standard pressure and temperature, fluorine is a pale yellow gas composed of diatomic...

₄. This tetrahedral molecule is notable for having a remarkably narrow liquid range (its boiling point is only 4 °C above its melting point). It was first synthesized by John Davy

John Davy (chemist)

John Davy FRS was a British doctor, amateur chemist, and brother of the noted chemist Sir Humphry Davy, and cousin of Edmund Davy....

 in 1812.

Preparation

SiF₄ is a by-product of the production of phosphate

Phosphate

A phosphate, an inorganic chemical, is a salt of phosphoric acid. In organic chemistry, a phosphate, or organophosphate, is an ester of phosphoric acid. Organic phosphates are important in biochemistry and biogeochemistry or ecology. Inorganic phosphates are mined to obtain phosphorus for use in...

 fertilizer

Fertilizer

Fertilizer is any organic or inorganic material of natural or synthetic origin that is added to a soil to supply one or more plant nutrients essential to the growth of plants. A recent assessment found that about 40 to 60% of crop yields are attributable to commercial fertilizer use...

s, resulting from the attack of HF

Hydrofluoric acid

Hydrofluoric acid is a solution of hydrogen fluoride in water. It is a valued source of fluorine and is the precursor to numerous pharmaceuticals such as fluoxetine and diverse materials such as PTFE ....

 (derived from fluorapatite

Fluorapatite

Fluorapatite, often with the alternate spelling of fluoroapatite, is a mineral with the formula Ca53F . Fluorapatite is a hard crystalline solid. Although samples can have various color , the pure mineral is colorless as expected for a material lacking transition metals...

 protonolysis) on silicate

Silicate

A silicate is a compound containing a silicon bearing anion. The great majority of silicates are oxides, but hexafluorosilicate and other anions are also included. This article focuses mainly on the Si-O anions. Silicates comprise the majority of the earth's crust, as well as the other...

s. In the laboratory, the compound is prepared by heating BaSiF₆ >300 °C, whereupon the solid releases volatile SiF₄, leaving a residue of BaF₂. The required BaSiF₆ is prepared by treating aqueous hexafluorosilicic acid with barium chloride

Barium chloride

Barium chloride is the inorganic compound with the formula BaCl2. It is one of the most common water-soluble salts of barium. Like other barium salts, it is toxic and imparts a yellow-green coloration to a flame. It is also hygroscopic....

. The corresponding GeF₄ is prepared analogously, except that the thermal "cracking" requires 700 °C.

Uses

This volatile

Volatility (chemistry)

In chemistry and physics, volatility is the tendency of a substance to vaporize. Volatility is directly related to a substance's vapor pressure. At a given temperature, a substance with higher vapor pressure vaporizes more readily than a substance with a lower vapor pressure.The term is primarily...

 compound finds limited use in microelectronics and organic synthesis

Organic synthesis

Organic synthesis is a special branch of chemical synthesis and is concerned with the construction of organic compounds via organic reactions. Organic molecules can often contain a higher level of complexity compared to purely inorganic compounds, so the synthesis of organic compounds has...

.

Occurrence

Volcanic plumes contain significant amounts of silicon tetrafluoride, the daily production can reach several tonnes per day. The silicon tetrafluoride is partly hydrolysed and forms hexafluorosilicic acid.