1,1-Difluoroethane

1,1-Difluoroethane[1]
IUPAC name

1,1-Difluoroethane
Other names

difluoroethane
Freon 152a
ethylidene difluoride
ethylidene fluoride
HFC-152a
R-152a
Identifiers
CAS number 75-37-6 Y
PubChem 6368
ChemSpider 6128 Y
UNII 0B1U8K2ME0 Y
ChEMBL CHEMBL325493 Y
RTECS number KI1410000
Jmol-3D images Image 1
Properties
Molecular formula C2H4F2
Molar mass 66.05 g/mol
Density 2.7014 g/L @ 25 °C
Melting point

-117 °C, 156 K, -179 °F
Boiling point

-25 °C, 248 K, -13 °F
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
MSDS MSDS for 1,1-difluoroethane
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Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

1,1-Difluoroethane 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 or HFC-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.

Contents

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 percursor 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.

Safety

The practice of huffing canned air can be extremely dangerous or fatal. The intentional inhalation of 1,1-difluoroethane 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]

In a Du Pont study, rats were exposed to up to 25,000ppm (67,485 mg/m3) for six hours daily, five days a week for two years. This has become the NOAEL for this substance. Prolonged exposure to difluoroethane has been linked in humans to the development of coronary heart-disease and angina.[7]

See also

References

  1. ^ 1,1-Difluoroethane at Sigma-Aldrich
  2. ^ "Global Warming Potentials of ODS Substitutes". U.S. Environmental Protection Agency. 2010. http://www.epa.gov/ozone/geninfo/gwps.html. 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. PMID 17132266. http://openurl.ingenta.com/content/nlm?genre=article&issn=0146-4760&volume=30&issue=8&spage=638&aulast=Hahn. 
  7. ^ "1,1-Difluoroethane". National Library of Medicine HSDB Database. 1994. http://toxnet.nlm.nih.gov/cgi-bin/sis/search/r?dbs+hsdb:@term+@rn+75-37-6. Retrieved 8 June 2010.