Tetrafluoromethane, also known as carbon tetrafluoride or R-14, is the simplest

perfluorocarbon Fluorocarbons are chemical compounds with carbon-fluorine bonds. Compounds that contain many C-F bonds often have distinctive properties, e.g., enhanced stability, volatility, and hydrophobicity. Several fluorocarbons and their derivatives are ...

( C F₄). As its IUPAC name indicates, tetrafluoromethane is the perfluorinated counterpart to the hydrocarbon

methane Methane ( , ) is a chemical compound with the chemical formula (one carbon atom bonded to four hydrogen atoms). It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas. The abundance of methane on Earth makes ...

. It can also be classified as a

haloalkane The haloalkanes (also known as halogenoalkanes or alkyl halides) are alkanes containing one or more halogen substituents of hydrogen atom. They are a subset of the general class of halocarbons, although the distinction is not often made. Haloalka ...

halomethane Halomethane compounds are derivatives of methane () with one or more of the hydrogen atoms replaced with halogen atoms (Fluorine, F, Chlorine, Cl, Bromine, Br, or Iodine, I). Halomethanes are both naturally occurring, especially in marine environm ...

. Tetrafluoromethane is a useful

refrigerant A refrigerant is a working fluid used in the cooling, heating, or reverse cooling/heating cycles of air conditioning systems and heat pumps, where they undergo a repeated phase transition from a liquid to a gas and back again. Refrigerants are ...

but also a potent

greenhouse gas Greenhouse gases (GHGs) are the gases in the atmosphere that raise the surface temperature of planets such as the Earth. Unlike other gases, greenhouse gases absorb the radiations that a planet emits, resulting in the greenhouse effect. T ...

. It has a very high bond strength due to the nature of the

carbon–fluorine bond The carbon–fluorine bond is a polar covalent bond between carbon and fluorine that is a component of all organofluorine compounds. It is one of the strongest single bonds in chemistry (after the B–F single bond, Si–F single bond, and H–F ...

Bonding

Because of the multiple carbon–fluorine bonds, and the high

electronegativity Electronegativity, symbolized as , is the tendency for an atom of a given chemical element to attract shared electrons (or electron density) when forming a chemical bond. An atom's electronegativity is affected by both its atomic number and the ...

fluorine Fluorine is a chemical element; it has Chemical symbol, symbol F and atomic number 9. It is the lightest halogen and exists at Standard temperature and pressure, standard conditions as pale yellow Diatomic molecule, diatomic gas. Fluorine is extre ...

, the carbon in tetrafluoromethane has a significant positive

partial charge In atomic physics, a partial charge (or net atomic charge) is a non-integer charge value when measured in elementary charge units. It is represented by the Greek lowercase delta (𝛿), namely 𝛿− or 𝛿+. Partial charges are created due to ...

which strengthens and shortens the four carbon–fluorine bonds by providing additional ionic character. Carbon–fluorine bonds are the strongest single bonds in

organic chemistry Organic chemistry is a subdiscipline within chemistry involving the science, scientific study of the structure, properties, and reactions of organic compounds and organic matter, organic materials, i.e., matter in its various forms that contain ...

. Additionally, they strengthen as more carbon–fluorine bonds are added to the same carbon atom. In the one-carbon organofluorine compounds represented by molecules of

fluoromethane Fluoromethane, also known as methyl fluoride, Freon 41, Halocarbon-41 and HFC-41, is a non-toxic, liquefiable, and flammable gas at standard temperature and pressure. It is made of carbon, hydrogen, and fluorine. The name stems from the fact that ...

, difluoromethane, trifluoromethane, and tetrafluoromethane, the carbon–fluorine bonds are strongest in tetrafluoromethane. This effect is due to the increased coulombic attractions between the fluorine atoms and the carbon because the carbon has a positive

of 0.76.

Preparation

Tetrafluoromethane is the product when any carbon compound, including carbon itself, is burned in an atmosphere of fluorine. With hydrocarbons,

hydrogen fluoride Hydrogen fluoride (fluorane) is an Inorganic chemistry, inorganic compound with chemical formula . It is a very poisonous, colorless gas or liquid that dissolves in water to yield hydrofluoric acid. It is the principal industrial source of fluori ...

is a coproduct. It was first reported in 1926. It can also be prepared by the

fluorination In chemistry, halogenation is a chemical reaction which introduces one or more halogens into a chemical compound. Halide-containing compounds are pervasive, making this type of transformation important, e.g. in the production of polymers, drugs. ...

carbon dioxide Carbon dioxide is a chemical compound with the chemical formula . It is made up of molecules that each have one carbon atom covalent bond, covalently double bonded to two oxygen atoms. It is found in a gas state at room temperature and at norma ...

carbon monoxide Carbon monoxide (chemical formula CO) is a poisonous, flammable gas that is colorless, odorless, tasteless, and slightly less dense than air. Carbon monoxide consists of one carbon atom and one oxygen atom connected by a triple bond. It is the si ...

phosgene Phosgene is an organic chemical compound with the formula . It is a toxic, colorless gas; in low concentrations, its musty odor resembles that of freshly cut hay or grass. It can be thought of chemically as the double acyl chloride analog of ...

with sulfur tetrafluoride. Commercially it is manufactured by the reaction of

with

dichlorodifluoromethane Dichlorodifluoromethane (R-12) is a colorless gas popularly known by the genericized brand name Freon (as Freon-12). It is a chlorofluorocarbon halomethane (CFC) used as a refrigerant and aerosol spray propellant. In compliance with the Montreal ...

or chlorotrifluoromethane; it is also produced during the

electrolysis In chemistry and manufacturing, electrolysis is a technique that uses Direct current, direct electric current (DC) to drive an otherwise non-spontaneous chemical reaction. Electrolysis is commercially important as a stage in the separation of c ...

of metal

fluoride Fluoride (). According to this source, is a possible pronunciation in British English. is an Inorganic chemistry, inorganic, Monatomic ion, monatomic Ion#Anions and cations, anion of fluorine, with the chemical formula (also written ), whose ...

s MF, MF₂ using a carbon electrode. Although it can be made from a myriad of precursors and fluorine, elemental fluorine is expensive and difficult to handle. Consequently, is prepared on an industrial scale using

: :CCl₂F₂ + 2 HF → CF₄ + 2 HCl

Laboratory synthesis

Tetrafluoromethane and

silicon tetrafluoride Silicon tetrafluoride or tetrafluorosilane is a chemical compound with the formula Si F4. This colorless gas is notable for having a narrow liquid range: its boiling point is only 4 °C above its melting point. It was first prepared in 1771 ...

can be prepared in the laboratory by the reaction of

silicon carbide Silicon carbide (SiC), also known as carborundum (), is a hard chemical compound containing silicon and carbon. A wide bandgap semiconductor, it occurs in nature as the extremely rare mineral moissanite, but has been mass-produced as a powder a ...

with fluorine. : SiC + 4 F₂ → CF₄ + SiF₄

Reactions

Tetrafluoromethane, like other fluorocarbons, is very stable due to the strength of its carbon–fluorine bonds. The bonds in tetrafluoromethane have a bonding energy of 515 kJ⋅mol⁻¹. As a result, it is inert to acids and hydroxides. However, it reacts explosively with

alkali metal The alkali metals consist of the chemical elements lithium (Li), sodium (Na), potassium (K),The symbols Na and K for sodium and potassium are derived from their Latin names, ''natrium'' and ''kalium''; these are still the origins of the names ...

Thermal decomposition Thermal decomposition, or thermolysis, is a chemical decomposition of a substance caused by heat. The decomposition temperature of a substance is the temperature at which the substance chemically decomposes. The reaction is usually endothermic ...

or combustion of CF₄ produces toxic gases (

carbonyl fluoride Carbonyl fluoride is a chemical compound with the formula . It is a carbon oxohalide. This gas, like its analog phosgene, is colourless and highly toxic. The molecule is planar with ''C''2v symmetry, bond lengths of 1.174 Å (C=O) and 1.312 Å ( ...

and

) and in the presence of water will also yield

. It is very slightly soluble in water (about 20 mg⋅L⁻¹), but miscible with organic solvents.

Uses

Tetrafluoromethane is sometimes used as a low temperature

(R-14). It is used in

electronics Electronics is a scientific and engineering discipline that studies and applies the principles of physics to design, create, and operate devices that manipulate electrons and other Electric charge, electrically charged particles. It is a subfield ...

microfabrication Microfabrication is the process of fabricating miniature structures of micrometre scales and smaller. Historically, the earliest microfabrication processes were used for integrated circuit fabrication, also known as "semiconductor manufacturing" ...

alone or in combination with

oxygen Oxygen is a chemical element; it has chemical symbol, symbol O and atomic number 8. It is a member of the chalcogen group (periodic table), group in the periodic table, a highly reactivity (chemistry), reactive nonmetal (chemistry), non ...

as a plasma etchant for

silicon Silicon is a chemical element; it has symbol Si and atomic number 14. It is a hard, brittle crystalline solid with a blue-grey metallic lustre, and is a tetravalent metalloid (sometimes considered a non-metal) and semiconductor. It is a membe ...

silicon dioxide Silicon dioxide, also known as silica, is an oxide of silicon with the chemical formula , commonly found in nature as quartz. In many parts of the world, silica is the major constituent of sand. Silica is one of the most complex and abundan ...

, and

silicon nitride Silicon nitride is a chemical compound of the elements silicon and nitrogen. (''Trisilicon tetranitride'') is the most thermodynamically stable and commercially important of the silicon nitrides, and the term ″''Silicon nitride''″ commonly re ...

.K. Williams, K. Gupta, M. Wasilik. ''Etch Rates for Micromachining Processing – Part II'' J. Microelectromech. Syst., vol. 12, pp. 761–777, December 2003. It also has uses in neutron detectors.

Environmental effects

Tetrafluoromethane is a potent

that contributes to the

greenhouse effect The greenhouse effect occurs when greenhouse gases in a planet's atmosphere insulate the planet from losing heat to space, raising its surface temperature. Surface heating can happen from an internal heat source (as in the case of Jupiter) or ...

. It is very stable, has an

atmospheric lifetime Greenhouse gases (GHGs) are the gases in the atmosphere that raise the surface temperature of planets such as the Earth. Unlike other gases, greenhouse gases absorb the radiations that a planet emits, resulting in the greenhouse effect. T ...

of 50,000 years, and a high greenhouse warming potential 6,500 times that of CO₂. Tetrafluoromethane is the most abundant

in the atmosphere, where it is designated as PFC-14. Its atmospheric concentration is growing: its preindustrial concentration produced via radioactive oxidation of

fluorite Fluorite (also called fluorspar) is the mineral form of calcium fluoride, CaF2. It belongs to the halide minerals. It crystallizes in isometric cubic habit, although octahedral and more complex isometric forms are not uncommon. The Mohs scal ...

and reaction with organic molecules was less than 40 parts per trillion. As of 2019, the man-made gases CFC-11 and CFC-12 continue to contribute a stronger

radiative forcing Radiative forcing (or climate forcing) is a concept used to quantify a change to the balance of energy flowing through a planetary atmosphere. Various factors contribute to this change in energy balance, such as concentrations of greenhouse gases ...

than PFC-14. Although structurally similar to

chlorofluorocarbons Chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) are fully or partly halogenated hydrocarbons that contain carbon (C), hydrogen (H), chlorine (Cl), and fluorine (F). They are produced as volatile derivatives of methane, ethane, ...

(CFCs), tetrafluoromethane does not deplete the ozone layer because the carbon–fluorine bond is much stronger than that between carbon and chlorine. Main industrial emissions of tetrafluoromethane besides

hexafluoroethane Hexafluoroethane is an organofluorine compound with the chemical formula . It is a non-flammable colorless odorless gas negligibly soluble in water and slightly soluble in methanol. Its structure is . It is an extremely potent and long-lived green ...

are produced during production of

aluminium Aluminium (or aluminum in North American English) is a chemical element; it has chemical symbol, symbol Al and atomic number 13. It has a density lower than that of other common metals, about one-third that of steel. Aluminium has ...

using Hall-Héroult process. CF₄ also is produced as product of the breakdown of more complex compounds such as

halocarbon Halocarbon compounds are chemical compounds in which one or more carbon atoms are linked by covalent bonds with one or more halogen atoms (fluorine, chlorine, bromine or iodine – ) resulting in the formation of organofluorine compounds, or ...

Health risks

Due to its density, tetrafluoromethane can displace air, creating an

asphyxiation Asphyxia or asphyxiation is a condition of deficient supply of oxygen to the body which arises from abnormal breathing. Asphyxia causes generalized hypoxia, which affects all the tissues and organs, some more rapidly than others. There are ...

hazard in inadequately ventilated areas. Otherwise, it is normally harmless due to its stability.

Notes

References

External links

*
National Pollutant Inventory – Fluoride and compounds fact sheetData from Air Liquide

Vapor pressure graph at Air LiquideProtocol for measurement of tetrafluoromethane and hexafluoroethane from primary aluminium productionChemical and physical properties table

WebBook page for CF4
{{Authority control Nonmetal halides 1 Halomethanes Refrigerants Greenhouse gases