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Structural formula
Structure of dichlorofluoromethane
Surname Dichlorofluoromethane
other names
  • R-21
  • Monofluorodichloromethane
  • Freon 21
  • Fluorodichloromethane
  • Dichloromonofluoromethane
Molecular formula CHCl 2 F
Brief description

colorless gas with an ethereal odor

External identifiers / databases
CAS number 75-43-4
EC number 200-869-8
ECHA InfoCard 100,000,791
PubChem 6370
Wikidata Q418163
Molar mass 102.92 g mol −1
Physical state



4.41 g cm −3 (15 ° C, 1 hPa)

Melting point

−135 ° C

boiling point

8.9 ° C

Vapor pressure

153 k Pa (20 ° C)


heavy in water (9.42 g l −1 )

safety instructions
GHS labeling of hazardous substances
04 - gas bottle 07 - Warning


H and P phrases H: 280-420
P: 410 + 403

Switzerland: 10 ml m −3 or 40 mg m −3

Global warming potential

179 (based on 100 years)

As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Dichlorofluoromethane is a chemical compound from the group of aliphatic, saturated fluorochlorohydrocarbons . It is a refrigerant and propellant that came to be known as Freon 21 , among other things .


The density of the liquid phase of dichlorofluoromethane at the boiling point is 1.4048 kg / l at 1 bar and 15 ° C. The critical temperature is 178.5 ° C, the critical pressure is 51.7 bar, the critical density is 0.522 g / cm 3 , the triple point is at a temperature of −135 ° C (melting temperature). Dichlorofluoromethane is listed on the Montreal Protocol and its ozone depletion potential is 0.040. In addition, dichlorofluoromethane is a greenhouse gas with an average lifetime in the atmosphere of 1.7 years and a global warming potential of 148 over a century.


Dichlorofluoromethane was used in cooling technology as a refrigerant and as an inert propellant for aerosols and foams . Today its use is prohibited because of the ozone depletion potential.

Web links

Individual evidence

  1. a b c d e f g Entry on dichlorofluoromethane in the GESTIS substance database of the IFA , accessed on February 1, 2016(JavaScript required) .
  2. Data sheet Dichlorofluoromethane from Sigma-Aldrich , accessed on May 7, 2015 ( PDF ).
  3. Swiss Accident Insurance Fund (Suva): Limit values ​​- current MAK and BAT values (search for 75-43-4 or dichlorofluoromethane ), accessed on November 2, 2015.
  4. G. Myhre, D. Shindell et al .: Climate Change 2013: The Physical Science Basis . Working Group I contribution to the IPCC Fifth Assessment Report. Ed .: Intergovernmental Panel on Climate Change . 2013, Chapter 8: Anthropogenic and Natural Radiative Forcing, pp. 24-39; Table 8.SM.16 ( PDF ).
  5. G. Myhre, D. Shindell, F.-M. Bréon, W. Collins, J. Fuglestvedt, J. Huang, D. Koch, J.-F. Lamarque, D. Lee, B. Mendoza, T. Nakajima, A. Robock, G. Stephens, T. Takemura, H. Zhang: Anthropogenic and Natural Radiative Forcing . In: Thomas F. Stocker, D. Qin, G.-K. Plattner, M. Tignor, SK Allen, J. Boschung, A. Nauels, Y. Xia, V. Bex, PM Midgley (eds.): Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press, Cambridge / New York 2013, ISBN 978-1-107-66182-0 , Table 8.A.1.