1,1-Difluoroethane

From Wikipedia, the free encyclopedia
Jump to: navigation, search
1,1-Difluoroethane[1]
Difluoroethane Difluoroethane
Difluoroethane
Identifiers
CAS number 75-37-6 YesY
PubChem 6368
ChemSpider 6128 YesY
UNII 0B1U8K2ME0 YesY
ChEMBL CHEMBL325493 YesY
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 (−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
MSDS MSDS for 1,1-difluoroethane
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
 YesY (verify) (what is: YesY/N?)
Infobox references

1,1-Difluoroethane, also 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.[citation needed]

Production[edit]

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[edit]

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[edit]

The practice of deliberately inhaling or “huffing” canned air can be extremely dangerous or 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] Due to inhalant abuse, a bitterant is added to consumer canned air products.

In a Du Pont 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 heart-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[edit]

References[edit]

  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.