1,1-Difluoroethane

1,1-Difluoroethane^[1]

Names
IUPAC name 1,1-Difluoroethane
Other names difluoroethane Freon 152a ethylidene difluoride ethylidene fluoride HFC-152a R-152a DFE
Identifiers
CAS Number	75-37-6
ChEMBL	ChEMBL325493
ChemSpider	6128
Jmol interactive 3D	Image
PubChem	6368
RTECS number	KI1410000
UNII	0B1U8K2ME0
InChI InChI=1S/C2H4F2/c1-2(3)4/h2H,1H3 Key: NPNPZTNLOVBDOC-UHFFFAOYSA-N InChI=1/C2H4F2/c1-2(3)4/h2H,1H3 Key: NPNPZTNLOVBDOC-UHFFFAOYAM
SMILES FC(F)C
Properties
Chemical formula	C2H4F2
Molar mass	66.05 g/mol
Density	2.7014 g/L @ 25 °C
Melting point	−117 °C (−179 °F; 156 K)
Boiling point	−25 °C (−13 °F; 248 K)
Solubility in water	0.54% @ 0 °C
Vapor pressure	4020 mmHg/536 kPa @ 21.1 °C 5.1 bar/510 kPa @ 20 °C
Viscosity	0.00887 cP (8.87 µPa·s) @ 25 °C
Hazards
Safety data sheet	MSDS for 1,1-difluoroethane
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

1,1-Difluoroethane, or DFE, is an organofluorine compound with the chemical formula C₂H₄F₂. This colorless gas is used as a refrigerant, where it is often listed as R-152a (refrigerant-152a) or HFC-152a (hydrofluorocarbon-152a). As an alternative to chlorofluorocarbons, it has an ozone depletion potential of zero, a lower global warming potential (120) and a shorter atmospheric lifetime (1.4 years).^[2] It has recently been approved for use in automobile applications as an alternative to R-134a.

Production

1,1-Difluoroethane is produced by the mercury-catalyzed addition of hydrogen fluoride to acetylene:^[3]

HCCH + 2 HF → CH₃CHF₂

The intermediate in this process is vinyl fluoride, the monomeric precursor to polyvinyl fluoride.

Uses

In addition to serving as a refrigerant, 1,1-difluoroethane is also commonly used in gas duster (commonly thought of as "canned air") and many consumer aerosol products, especially those subject to stringent VOC requirements.

The molecular weight of difluoroethane is 66, making it useful and convenient tool for detecting vacuum leaks in GC-MS systems.

Safety

The practice of deliberately inhaling or “huffing” canned air is extremely dangerous and can be fatal. It caused a fatal cardiac arrhythmia in a 42-year-old man.^[4] Several reports of fatal car crashes have been linked to drivers huffing 1,1-difluoroethane.^[5][6][7] Because of inhalant abuse, a bitterant is added to consumer canned air products.

In a DuPont study, rats were exposed to up to 25,000 ppm (67,485 mg m⁻³) for six hours daily, five days a week for two years. This has become the no-observed-adverse-effect level for this substance. Prolonged exposure to 1,1-difluoroethane has been linked in humans to the development of coronary disease and angina.^[8]

Though not extremely flammable in gaseous form, 1,1-difluoroethane can burn under some conditions. As such, there is also a warning label present on some gas dusters. When inverted to spray liquid, the boiling fluorocarbon aerosol is easily ignitable, producing a very large blast of flame and extremely toxic gases such as hydrogen fluoride and carbonyl fluoride as combustion products.

See also

• List of refrigerants
• Canned air

References

1. 1,1-Difluoroethane at Sigma-Aldrich
2. "Global Warming Potentials of ODS Substitutes". U.S. Environmental Protection Agency. 2010. Archived from the original on 16 October 2010. Retrieved 20 September 2010.
3. Siegemund, Günter; Schwertfeger, Werner; Feiring, Andrew; Smart, Bruce; Behr, Fred; Vogel, Herward; McKusick, Blaine (2010). "Fluorine Compounds, Organic". In Bohnet, Matthias; Bellussi, Giuseppe; Bus, James; et al. Ullmann's Encyclopedia of Industrial Chemistry. John Wiley & Sons. doi:10.1002/14356007.a11_349.
4. Avella J, Wilson JC, Lehrer M (March 2006). "Fatal cardiac arrhythmia after repeated exposure to 1,1-difluoroethane (DFE)". The American Journal of Forensic Medicine and Pathology 27 (1): 58–60. doi:10.1097/01.paf.0000202715.71009.0e. PMID 16501351.
5. Broussard LA, Brustowicz T, Pittman T, Atkins KD, Presley L (November 1997). "Two traffic fatalities related to the use of difluoroethane". Journal of Forensic Sciences 42 (6): 1186–7. PMID 9397568.
6. Hahn T, Avella J, Lehrer M (October 2006). "A motor vehicle accident fatality involving the inhalation of 1,1-difluoroethane". Journal of Analytical Toxicology 30 (8): 638–42. doi:10.1093/jat/30.8.638. PMID 17132266. Retrieved 6 June 2010.
7. "Autopsy: man in crash died from inhaling computer cleaner". The Times News. 10 March 2012.
8. "1,1-Difluoroethane". National Library of Medicine HSDB Database. 1994. Retrieved 8 June 2010.