1,1,1,2-Tetrafluoroethane (also known as norflurane (
INN), R-134a, Klea 134a, Freon 134a, Forane 134a, Genetron 134a, Green Gas, Florasol 134a, Suva 134a, HFA-134a, or HFC-134a) is a
hydrofluorocarbon (HFC) and
haloalkanerefrigerant with thermodynamic properties similar to
R-12 (dichlorodifluoromethane) but with insignificant
ozone depletion potential and a lower 100-year
global warming potential (1,430, compared to R-12's GWP of 10,900).[1] It has the formula CF3CH2F and a
boiling point of −26.3 °C (−15.34 °F) at atmospheric pressure. R-134a cylinders are colored
light blue.[2] A phaseout and transition to
HFO-1234yf and other refrigerants, with GWPs similar to CO2, began in 2012 within the automotive market.[3]
Uses
1,1,1,2-Tetrafluoroethane is a
non-flammable gas used primarily as a "high-temperature" refrigerant for domestic
refrigeration and
automobile air conditioners. These devices began using 1,1,1,2-tetrafluoroethane in the early 1990s as a replacement for the more environmentally harmful
R-12. Retrofit kits are available to convert units that were originally R-12-equipped.
Other common uses include plastic foam blowing, as a cleaning solvent, a propellant for the delivery of pharmaceuticals (e.g.
bronchodilators), wine cork removers,
gas dusters ("canned air"), and in air driers for removing the moisture from
compressed air. 1,1,1,2-Tetrafluoroethane has also been used to cool computers in some
overclocking attempts. It is the refrigerant used in plumbing pipe freeze kits. It is also commonly used as a propellant for
airsoft airguns. The gas is often mixed with a silicone-based lubricant.
1,1,1,2-Tetrafluoroethane was introduced in the early 1990s as a replacement for
dichlorodifluoromethane (R-12), which has massive ozone depleting properties.[11] Even though 1,1,1,2-Tetrafluoroethane has insignificant ozone depletion potential (
ozone layer) and negligible acidification potential (
acid rain), it has a 100-year
global warming potential (GWP) of 1430 and an approximate
atmospheric lifetime of 14 years.[1] Its concentration in the atmosphere and contribution to
radiative forcing have been growing since its introduction. Thus it was included in the
IPCC list of greenhouse gases.[12]
R-134a began being phased out from use in the
European Union, starting in the mid 2010s, by a directive of 2006, recommending the replacement of gases in air conditioning systems with a GWP above 100.[13]
1,1,1,2-tetrafluoroethane is subject to use restrictions in the US and other countries as well. The Society of Automotive Engineers (SAE) has proposed that it be best replaced by a new fluorochemical refrigerant
HFO-1234yf (CF3CF=CH2) in automobile air-conditioning systems.[14] By model year 2021, newly manufactured light-duty vehicles in the United States will no longer use R-134a.[3]
California may also prohibit the sale of canned R-134a to individuals to avoid non-professional recharge of air conditioners.[15] A ban had 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 applied only when the chemical was intended to be a refrigerant. However, the ban was lifted in Wisconsin in 2012.[16] During the time that it was active, this Wisconsin-specific ban contained loopholes. For example, it was 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 [16] nor is HFC-134a included in the § 7671a listing of class I and class II substances.[17]
It reacts with butyllithium to give trifluorovinyl lithium:[19]
CF3CH2F + 2 BuLi → CF2=CFLi + LiF + 2 BuH
Safety
Mixtures with air of the gas 1,1,1,2-tetrafluoroethane are not
flammable at atmospheric pressure and temperatures up to 100 °C (212 °F). However, mixtures with high concentrations of air at elevated pressure and/or temperature can be
ignited.[20] 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 fluoride,[21] however the decomposition temperature has been reported as above 370 °C.[22] 1,1,1,2-Tetrafluoroethane itself has an
LD50 of 1,500 g/m3 in rats, making it relatively non-toxic, apart from the dangers inherent to
inhalant abuse. Its gaseous form is denser than air and will displace air in the lungs. This can result in
asphyxiation if excessively inhaled.[23][24] This contributes to most deaths by
inhalant abuse.
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.
^Corr, Stuart (2005). "1,1,1,2-Tetrafluoroethane (R-134a): A Selective Solvent for the Generation of Flavor and Fragrance Ingredients". Natural Flavors and Fragrances. ACS Symposium Series. Vol. 908. p. 41.
doi:
10.1021/bk-2005-0908.ch003.
ISBN0-8412-3904-5.
^Abbott, Andrew P.; Eltringham, Wayne; Hope, Eric G.; Nicola, Mazin (2005). "Solubility of unsaturated carboxylic acids in supercritical 1,1,1,2-tetrafluoroethane (HFC 134a) and a methodology for the separation of ternary mixtures". Green Chemistry. 7 (4): 210.
doi:
10.1039/B412697A.
^Forster, P.; et al. (2007).
"Changes in Atmospheric Constituents and in Radiative Forcing."(PDF). Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change.
Archived(PDF) from the original on 24 July 2010.
^Burdon, James; Coe, Paul L.; Haslock, Iain B.; Powell, Richard L. (1996). "The hydrofluorocarbon 1,1,1,2-tetrafluoroethane (HFC-134a) as a ready source of trifluorovinyllithium". Chemical Communications: 49.
doi:
10.1039/CC9960000049.
^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.