1,1,1,2-Tetrafluoroethane

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1,1,1,2-Tetrafluoroethane
IUPAC name	1,1,1,2-Tetrafluoroethane
Other names	Genetron 134a HFA-134a HFC-134a R-134a Suva 134a Norflurane
Identifiers
CAS number	811-97-2 Y
EC number	212-377-0
RTECS number	KI8842500
SMILES	FC(F)(F)C(F)
Properties
Molecular formula	C2H2F4
Molar mass	102.03 g/mol
Appearance	Colorless gas
Density	0.00425 g/cm³, 4.25 Kg/m³, gas
Melting point	-103.3°C (169.85 K)
Boiling point	-26.3°C (246.85 K)
Solubility in water	0.15 wt%
Hazards
MSDS	External MSDS
S-phrases	(S2), S23, S24/25, S51
NFPA 704	1 1 1
Flash point	Non-flammable
Related compounds
Related refrigerants	Difluoromethane Pentafluoroethane
Related compounds	1,1,2,2,2-pentafluoroethane 2-Chloro- 1,1,1,2-tetrafluoroethane 1,1,1-Trichloroethane
Supplementary data page
Structure and properties	n, εr, etc.
Thermodynamic data	Phase behaviour Solid, liquid, gas
Spectral data	UV, IR, NMR, MS
Y (what is this?)  (verify) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

1,1,1,2-Tetrafluoroethane, R-134a, Genetron 134a, Suva 134a or HFC-134a, is a haloalkane refrigerant with thermodynamic properties similar to R-12 (dichlorodifluoromethane), but with less ozone depletion potential. It has the formula CH₂FCF₃, and a boiling point of −26.3 °C (−15.34 °F).

[edit] Uses

1,1,1,2-Tetrafluoroethane is an inert gas used primarily as a "high-temperature" refrigerant for domestic refrigeration and automobile air conditioners. Other uses include plastic foam blowing, as a cleaning solvent and as a propellant for the delivery of pharmaceuticals (e.g. bronchodilators), gas dusters, and in air driers, for removing the moisture from compressed air. Moisture present in compressed air has a harmful effect on pneumatic systems. 1,1,1,2-Tetrafluoroethane has also been used to cool computers in some overclocking attempts. It is also commonly used as a propellant for airsoft airguns.

Tetrafluoroethane, when compressed as inside gas duster cans, is a clear liquid which boils when exposed to room temperature (as seen here) and can be extracted from common canned air canisters by simply inverting them during use.

Recently, 1,1,1,2-tetrafluoroethane has been subject to use restrictions due to its contribution to climate change. In the EU, it will be banned as from 2011 in all new cars.^[1] The Society of Automotive Engineers (SAE) has proposed 1,1,1,2-tetrafluoroethane (HFC-134a) to be best replaced by a new fluorochemical refrigerant HFO-1234yf (CF3CF=CH2) in automobile air-conditioning systems.^[2] California may prohibit the sale of canned 1,1,1,2-tetrafluoroethane to individuals to avoid non-professional recharge of air conditioners. A ban has been in place in Wisconsin since October 1994 under ATCP 136 prohibiting sales of container sizes holding less than 15 lbs of 1,1,1,2-tetrafluoroethane, but this restriction applies only when the chemical is intended to be a refrigerant.^[3] It appears, for example, that it is legal for a person to purchase Gas duster containers with any amount of the chemical because in that instance the chemical is neither intended to be a refrigerant ^[3] nor is HFC-134a included in the § 7671a listing of class I and class II substances.^[4] The chemical has also been banned in mobile air conditioners in the state of California. ^[5]

[edit] History

1,1,1,2-Tetrafluoroethane first appeared in the early 1990s as a replacement for dichlorodifluoromethane (R-12), which has supposed ozone depleting properties.^[6] 1,1,1,2-Tetrafluoroethane has been atmospherically modeled for its impact on depleting ozone and as a contributor to global warming. Research suggests that over the past 10 years the concentration of 1,1,1,2-tetrafluoroethane has increased significantly in the Earth's atmosphere, with a recent study revealing a doubling in atmospheric concentration between 2001–2004.^[7] It has insignificant ozone depletion potential (ozone layer), significant global warming potential (GWP = 1300)^[8] and negligible acidification potential (acid rain). 1,1,1,2-Tetrafluoroethane is slowly converted to trifluoroacetic acid through a radical reaction in the upper atmosphere and leads to a detectable amount of several ng/L in acid rain in some models.^[9]

[edit] Safety

Contact of 1,1,1,2-tetrafluoroethane with flames or hot surfaces in excess of 250 °C (482 °F) may cause vapor decomposition and the emission of toxic gases including hydrogen fluoride and carbonyl halides.^[10] 1,1,1,2-Tetrafluoroethane itself has an LD₅₀ (lethal concentration for 50% of subjects) in rats of 1,500 g/m³, making it relatively non-toxic. However, its gaseous form is denser than air, and will displace air in the lungs. This can result in asphyxiation if excessively inhaled.^[11][12]

Aerosol cans containing 1,1,1,2-tetrafluoroethane, when inverted, become effective freeze sprays. Under pressure, 1,1,1,2-tetrafluoroethane is compressed into a liquid, which upon vaporization absorbs a significant amount of thermal energy. As a result, it will greatly lower the temperature of any object it contacts as it evaporates. This can result in frostbite when it contacts skin.

[edit] References

[edit] See also

• 1,1,1,2-Tetrafluoroethane (data page)
• Tetrabromoethane
• Tetrachloroethane

[edit] External links

Wikimedia Commons has media related to: Tetrafluoroethane

• International Chemical Safety Card 1281
• Information about HFCs, European Fluorocarbons Technical Committee (EFCTC)
• MSDS at Oxford University
• Concise International Chemical Assessment Document 11, at inchem.org
• Pressure temperature calculator
• The Coexisting Curve of the Refrigerant HFC 134a: Some Scaling Models
• R134a 2 phase computer cooling