1,1,1,2-Tetrafluoroethane

1,1,1,2-Tetrafluoroethane (also known as norflurane (INN), R-134a, Freon 134a, Forane 134a, Genetron 134a, Florasol 134a, Suva 134a, or HFC-134a) is a hydrofluorocarbon (HFC) and haloalkane refrigerant with thermodynamic properties similar to R-12 (dichlorodifluoromethane) but with insignificant ozone depletion potential and a significantly lower global warming potential (1,430, compared to R-12's GWP of 10,900).[2] 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.[3] Attempts at phasing out its use as a refrigerant with substances that have lower global warming potential, such as HFO-1234yf, are underway.

1,1,1,2-Tetrafluoroethane
Structure
3-D structure
Names
IUPAC name
1,1,1,2-Tetrafluoroethane
Other names
Freon 134a
Dymel 134a
Forane 134a
Genetron 134a
HFA-134a
HFC-134a
R-134a
Suva 134a
Norflurane
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.011.252
EC Number
  • 212-377-0
KEGG
RTECS number
  • KI8842500
UNII
Properties
CF3CH2F[1]
Molar mass 102.03 g/mol
Appearance Colorless gas
Density 0.00425 g/cm3, gas
Melting point −103.3 °C (−153.9 °F; 169.8 K)
Boiling point −26.3 °C (−15.3 °F; 246.8 K)
0.15 wt%
Hazards
Main hazards Asphyxiant
Safety data sheet See: data page
GHS pictograms
GHS Signal word Warning
GHS hazard statements
 H280
P410+403
NFPA 704 (fire diamond)
Flammability code 0: Will not burn. E.g. waterHealth code 1: Exposure would cause irritation but only minor residual injury. E.g. turpentineReactivity code 1: Normally stable, but can become unstable at elevated temperatures and pressures. E.g. calciumSpecial hazards (white): no code
0
1
1
Flash point 250 °C (482 °F; 523 K)
Related compounds
Related refrigerants
 Difluoromethane
Pentafluoroethane
Related compounds
 2-Chloro-
1,1,1,2-tetrafluoroethane
1,1,1-Trichloroethane
Supplementary data page
Refractive index (n),
Dielectric constant (εr), etc.
Thermodynamic
data
 Phase behaviour
solid–liquid–gas
UV, IR, NMR, MS
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Y verify (what is YN ?)
Infobox references

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 and retrofit kits are available to convert units that were originally R-12-equipped. Other uses include plastic foam blowing, as a cleaning solvent, a propellant for the delivery of pharmaceuticals (e.g. bronchodilators), wine cork removers, gas dusters, such as Dust-Off, 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.

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

Aspirational and niche applications

1,1,1,2-Tetrafluoroethane is also being considered as an organic solvent suitable for extraction of flavor and fragrance compounds, as a possible alternative to other organic solvents and supercritical carbon dioxide.[4][5] It can also be used as a solvent in organic chemistry, both in liquid and supercritical fluid.[6] It is used in the resistive plate chamber particle detectors in the Large Hadron Collider.[7][8] It is also used for other types of particle detectors, e.g. some cryogenic particle detectors.[9] It can be used as an alternative to sulfur hexafluoride in magnesium smelting as a shielding gas.[10]

1,1,1,2-Tetrafluoroethane is also being considered as an alternative to sulfur hexafluoride as a dielectric gas.[11] Its arc-quenching properties are poor, but its dielectric properties are fairly good.

Climate change considerations

1,1,1,2-tetrafluoroethane is subject to use restrictions due to its contribution to climate change.[12] It has a global warming potential of 1300.[13]

The Society of Automotive Engineers (SAE) has proposed 1,1,1,2-tetrafluoroethane to be best replaced by a new fluorochemical refrigerant HFO-1234yf (CF3CF=CH2) in automobile air-conditioning systems.[14] California may also prohibit the sale of canned 1,1,1,2-tetrafluoroethane 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]

History

1,1,1,2-Tetrafluoroethane first appeared in the early 1990s as a replacement for dichlorodifluoromethane (R-12), which has ozone depleting properties.[18] It has insignificant ozone depletion potential (ozone layer), significant global warming potential (100-yr GWP of 1430)[19] and negligible acidification potential (acid rain). Because of its high GWP, 1,1,1,2-tetrafluoroethane is due to be banned from use in the European Union, starting with cars in 2011 and due to be banned completely by 2030.[20]

Production and reactions

Tetrafluoroethane is typically made by reacting trichloroethylene with hydrogen fluoride:[21]

CHCl=CCl2 + 4 HF → CF3CH2F + 3 HCl

It reacts with butyllithium to give trifluorovinyl lithium:[22]

CF3CH2F + 2 BuLi → CF2=CFLi + LiF + 2 BuH

Safety
R-134a cylinder

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.[23] 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[24], however the decomposition temperature has been reported as above 370 °C, [25]. 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.[26][27] This is what 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.

Medical use

For its medical uses, 1,1,1,2-tetrafluoroethane has the generic name norflurane. It is used as propellant for some metered dose inhalers.[28] It is considered safe for this use.[29][30][31] In combination with pentafluoropropane, it is used as a topical vapocoolant spray for numbing boils before curettage.[32][33] It has also been studied as a potential inhalational anesthetic,[34] but it is nonanaesthetic at doses used in inhalers.[29]

gollark: There are some important considerations here: it should be able to deal with damaged/partial files, encryption would be nice to have (it would probably work to just run it through authenticated AES-whatever when writing), adding new files shouldn't require tons of seeking, and it might be necessary to store backups on FAT32 disks so maybe it needs to be able of using multiple files somehow.
gollark: Hmm, so, designoidal idea:- files have the following metadata: filename, last modified time, maybe permissions (I may not actually need this), size, checksum, flags (in case I need this later; probably just compression format?)- each version of a file in an archive has this metadata in front of it- when all the files in some set of data are archived, a header gets written to the end with all the file metadata plus positions- when backup is rerun, the system™ just checks the last modified time of everything and sees if its local copies are newer, and if so appends them to the end; when it is done a new header is added containing all the files- when a backup needs to be extracted, it just reads the end and decompresses stuff at the right offset
gollark: I don't know what you mean "dofs", data offsets?
gollark: Well, this will of course be rustaceous.
gollark: So that makes sense.

See also

References
  1. Global Warming Potentials of ODS Substitutes Ozone Layer Protection US EPA. Epa.gov (28 June 2006). Retrieved 21 August 2011.
  2. "Table 2.14 (Errata). Lifetimes, radiative efficiencies and direct (except for CH4) GWPs relative to CO2". Archived from the original on 6 July 2017. Retrieved 11 July 2017.
  3. "Example image of a 30 lbs R134a bottle". budgetheating.com. Retrieved 26 March 2018.
  4. 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. 908. p. 41. doi:10.1021/bk-2005-0908.ch003. ISBN 0-8412-3904-5.
  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.
  6. Abbott, Andrew P.; Eltringham, Wayne; Hope, Eric G.; Nicola, Mazin (2005). "Hydrogenation in supercritical 1,1,1,2 tetrafluoroethane (HFC 134a)" (PDF). Green Chemistry. 7 (10): 721. doi:10.1039/B507554H. hdl:2381/604.
  7. Anushree Ghosh STUDY OF GLASS RESISTIVE PLATE CHAMBERS (RPC) AND CALCULATION OF EFFICIENCY Archived 7 August 2011 at the Wayback Machine. INO Graduate Training Programme DHEP, TIFR, Mumbai.
  8. M. Capeans, I. Glushkov, R. Guida, F. Hahn, S. Haider (CERN, Switzerland) RPC operation at the LHC experiments in an optimized closed loop gas system. Medical Imaging Conference. 25–31 October 2009.
  9. Norbeck, E.; Olson, J. E.; Moeller, A.; Onel, Y. (2006). "Rad Hard Active Media For Calorimeters" (PDF). AIP Conference Proceedings. 867: 84. Bibcode:2006AIPC..867...84N. doi:10.1063/1.2396941. Archived from the original (PDF) on 23 March 2012.
  10. Magnesium recycling in the United States in 1998. (PDF). USGS. Retrieved 21 August 2011.
  11. Gaseous dielectrics with low global warming potentials – US Patent Application 20080135817 Description Archived 13 October 2012 at the Wayback Machine. Patentstorm.us (12 December 2006). Retrieved 21 August 2011.
  12. European Directive 2006/40/EC relating to emissions from air-conditioning systems in motor vehicles. (PDF). Retrieved 21 August 2011.
  13. Compressed air dusters and environmental concerns. (PDF). Retrieved 26 May 2015.
  14. HFO-1234yf A Low GWP Refrigerant For MAC Archived 27 February 2009 at the Wayback Machine. Refrigerants.dupont.com (17 August 2011). Retrieved 21 August 2011.
  15. California restricts use of HFC-134a in cars. 27 June 2007. R744.com. Retrieved 21 August 2011.
  16. Chapter ATCP 136. MOBILE AIR CONDITIONERS; RECLAIMING OR RECYCLING REFRIGERANT. State.wi.us. (PDF). Retrieved 21 August 2011.
  17. Class I Ozone-depleting Substances. EPA.gov. Retrieved 21 August 2011.
  18. Franklin J (1993). "The Atmospheric Degradation and Impact of 1,1,1,2-Tetrafluorethane (Hydrofluorocarbon 134a)". Chemosphere. 27 (8): 1565–1601. Bibcode:1993Chmsp..27.1565F. doi:10.1016/0045-6535(93)90251-Y.
  19. 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.
  20. "Refrigerant 1234YF's Potential Impact in Automotive Applications" (PDF). Archived (PDF) from the original on 13 July 2013. Retrieved 10 July 2013.
  21. http://www.solvay.us/en/binaries/PSS-Tetrafluoroethane-164368.pdf
  22. 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.
  23. DuPont (2004). DuPont HFC-134a— Properties, Uses, Storage, and Handling (PDF) (Report). Retrieved 5 August 2016.
  24. Honeywell International (December 2005). "MSDS # GTRN-0047 For Genetron 134aUV".
  25. "SAFETY DATA SHEET according to Regulation (EU) 2015/8301/7 Harp® 134a" (PDF).
  26. Alexander D. J; Libretto S. E. (1995). "An overview of the toxicology of HFA-134a (1,1,1,2-tetrafluoroethane)". Hum. Exp. Toxicol. 14 (9): 715–20. doi:10.1177/096032719501400903. PMID 8579881. S2CID 19669317.
  27. 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.
  28. Sellers, William F. S (2017). "Asthma pressurised metered dose inhaler performance: Propellant effect studies in delivery systems". Allergy, Asthma & Clinical Immunology. 13: 30. doi:10.1186/s13223-017-0202-0. PMC 5492461. PMID 28670327.
  29. Shah, S. B; Hariharan, U; Bhargava, A. K (2015). "Anaesthetic in the garb of a propellant". Indian Journal of Anaesthesia. 59 (4): 258–260. doi:10.4103/0019-5049.155011. PMC 4408662. PMID 25937660. This propellant has been shown to be safe and nonanaesthetic in standard inhaler doses
  30. Huchon, G; Hofbauer, P; Cannizzaro, G; Iacono, P; Wald, F (2000). "Comparison of the safety of drug delivery via HFA- and CFC-metered dose inhalers in CAO". The European Respiratory Journal. 15 (4): 663–9. doi:10.1034/j.1399-3003.2000.15d07.x. PMID 10780756.
  31. "1,1,1,2-Tetrafluoroethane". Occupational Safety & Health Administration.
  32. "Norflurane". DrugBank.
  33. "Norflurane-Pentafluoropropane Aerosol, Spray". WebMD.
  34. Shulman M, Sadove MS (1967). "1,1,1,2-tetrafluoroethane: an inhalational agent of intermediate potency". Anesthesia and Analgesia. 46 (5): 629–635. doi:10.1213/00000539-196709000-00029.
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