Freons are poly-chlorofluorinated derivatives of methane and ethane.

• Most common member: Freon-12 ($CC{l}_2{F}_2$).
• Properties: Extremely stable, non-toxic, non-corrosive, and easily liquefiable. This made them ideal for refrigeration, air conditioning, and as aerosol propellants.
• Environmental Issue: They migrate to the stratosphere, where they are dissociated by UV rays to release Chlorine free radicals ($C{l}^{.}$). These radicals act as catalysts to destroy the Ozone Layer.