Chlorofluorocarbons

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Definition of Chlorofluorocarbons

A chlorofluorocarbon (CFC) is an organic compound that contains only carbon, chlorine, and fluorine, produced as a volatile derivative of methane, ethane, and propane

More About Chlorofluorocarbons

  • Chlorofluorocarbons are also commonly known as Freon
  • The most common representative is dichlorodifluoromethane
  • Many Chlorofluorocarbons have been widely used as refrigerants, propellants (in aerosol applications), and solvents
  • The manufacture of such compounds (Chlorofluorocarbons) has been phased out under the Montreal Protocol, and are being replaced with products such as HFCs, hydrocarbons, and CO2, because Chlorofluorocarbons contribute to ozone depletion in the upper atmosphere
  • As in simpler alkanes, carbon in the Chlorofluorocarbons and the HCFCs is tetrahedral
  • Since the fluorine and chlorine atoms differ greatly in size and effective charge from hydrogen and from each other, the methane-derived Chlorofluorocarbons deviate from perfect tetrahedral symmetry
  • These Chlorofluorocarbons are less volatile
  • The decreased volatility is attributed to the molecular polarity induced by the halides, which induces intermolecular interactions
  • The densities of Chlorofluorocarbons are higher than their corresponding alkanes
  • The use of Chlorofluorocarbons has been heavily regulated because of their destructive effects on the ozone layer
  • Freon is a trade name for a group of Chlorofluorocarbons which are used primarily as refrigerants
  • Chlorofluorocarbons also have uses in fire-fighting and as propellants in aerosol cans
  • Bromomethane is widely used as a fumigant
  • Dichloromethane is a versatile industrial solvent
  • An effective exchange agent was developed to replace chloride in carbon tetrachloride with fluoride to synthesize CFC-11 (CCl3F) and CFC-12 (CCl2F2)
  • Later on Chlorofluorocarbons was used industrially as a refrigerant
  • Since the late 1970s, the use of Chlorofluorocarbons has been heavily regulated because of their destructive effects on the ozone layer
  • The Chlorofluorocarbons diffuse into upper stratosphere
  • Once in the stratosphere, the sun's ultraviolet radiation is strong enough to cause the homolytic cleavage of the C-Cl bond
  • Chlorofluorocarbons react there with the ozone layer and cause its depletion
  • As a result, more ultraviolet rays of sun reach the earth, and cause skin cancer
  • Work on alternatives for chlorofluorocarbons in refrigerants began in the late 1970s after the first warnings of damage to stratospheric ozone were published
  • This anthropogenic compound is also a greenhouse gas, with a much higher potential to enhance the greenhouse effect than CO2
  • The hydro chlorofluorocarbons (HCFCs) are less stable in the lower atmosphere, enabling them to break down before reaching the ozone layer

Applications:

  • Refrigeration & air-conditioning
  • Propellants in medicinal aerosols
  • Blowing agents for foam
  • Solvents, degreasing agents, cleaning agents