HFC-134a

1,1,1,2-Tetrafluoroethane

IUPAC name	1,1,1,2-Tetrafluoroethane
Other names	Genetron 134a HFC-134a R-134a Suva 134a Norflurane
Identifiers
CAS number	811-97-2
EINECS 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, 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
Main hazards	Asphyxiant
NFPA 704	1 1 1
S-phrases	(S2), S23, S24/25, S51
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, ε_r, etc.
Thermodynamic data	Phase behaviour Solid, liquid, gas
Spectral data	UV, IR, NMR, MS
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, also called simply tetrafluoroethane, R-134a, Genetron 134a, Suva 134a or HFC-134a, is a haloalkane refrigerant with thermodynamic properties similar to R-12 (dichlorodifluoromethane), but without its ozone depletion potential. It has the formula CH₂FCF₃, and a boiling point of −26.3 °C (−15.34 °F).

1 Uses
2 History
3 Safety
4 References
5 See also
6 External links

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. 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, R-134a has been subject to use restrictions due to its theorized contribution to climate change. In the EU, it will be banned as from 2011 in all new cars^[1]. SAE (International, an auto engineers association) has proposed 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 HFC-134a to individuals to avoid non-professional recharge of air conditioners. A ban has been in place in Wisconsin since Oct 1994 under ATCP 136 prohibiting sales of container sizes holding less than 15 lbs of refrigerant.^[3]

History

R-134a first appeared in the early 1990s as a replacement for Dichlorodifluoromethane (R-12), which has significant ozone depleting properties.^[4] R-134a 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.^[5] It has insignificant ozone depletion potential (ozone layer), significant global warming potential (GWP₁₀₀ = 1300) and negligible acidification potential (acid rain). In fact the top climate scientist at NASA, James Hansen, has advanced an alternative view of global warming wherein he argues the 0.74±0.18°C rise in average global temperatures over the last 100 years has been driven mainly by greenhouse gases other than carbon dioxide.^[6] 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.^[7]

Safety

Contact of 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.^[8] Tetrafluoroethane itself has an LC₅₀ (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.^[9]^[10]

Aerosol cans containing tetrafluoroethane, when inverted, become effective freeze sprays. Under pressure, 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.

References

^ European Directive 2006/40/EC relating to emissions from air-conditioning systems in motor vehicles
^ [http://refrigerants.dupont.com/Suva/en_US/pdf/DP_HW_2nd_European_Workshop_MAC.pdf HFO-1234yf A Low GWP Refrigerant For MAC Honeywell / DuPont Joint Collaboration]
^ Early Action Measure California: Use ban of canned HFC-134a
^ Franklin J (1993). "The Atmospheric Degradation and Impact of 1,1,1,2-Tetrafluorethane (Hydrofluorocarbon 134a)". Chemosphere 27: 1565–1601. doi:10.1016/0045-6535(93)90251-Y.
^ "Greenhouse gas monitoring at the Zeppelin station - Annual report 2004 (TA-2110/2005)". Norwegian Institute for Air Research. Retrieved on 2006-01-19.
^ http://www.pnas.org/cgi/content/full/97/18/9875
^ von Sydow L, Grimvall AB, Borén HB, Laniewski K, Nielsen AT (2000). "Natural Background Levels of Trifluoroacetate in Rain and Snow". Enviro Sci Technol 34: 3115–3118. doi:10.1021/es9913683.
^ Honeywell International (December 2005). MSDS # GTRN-0047 For Genetron 134aUV.
^ Alexander D. J, Libretto S. E. (1995). "An overview of the toxicology of HFA-134a (1,1,1,2-tetrafluoroethane)". Hum. Exp. Toxicol. 14: 715–20.
^ G. E. Millward, E. Tschuikow-Roux (1972). "Kinetic analysis of the shock wave decomposition of 1,1,1,2-tetrafluoroethane". The Journal of Physical Chemistry 76 (3): 292–298. doi:10.1021/j100647a002.