Freon, Halon, CFC, and Hydrochlorofluorocarbon and added to Alkyl halide.

Freon is a trade name for a group of chlorofluorocarbons used primarily as a refrigerant. The word Freon is a registered trademark belonging to DuPont. Prior to their implication as a major contributor to ozone depletion (and a minor contributor to the greenhouse effect), freons were also used as aerosol propellants and to foam up polymer materials.

Freon was developed as a safer alternative to toxic gases such as, ammonia (NH₃), methyl chloride (CH₃Cl), and sulfur dioxide (SO₂), that were used as refrigerants prior to the discovery of freon. Despite the controversy, R12 works well and is very safe. Its inventor, Thomas Midgley, actually breathed in a lungful and exhaled over a candle to demonstrate its nontoxicity and nonflammability.

Before CFCs were banned by developed nations, a 12 ounce (340 g) can of freon (R12) cost about $1; following the ban the cost of freon rose dramatically. People now go through considerable trouble to recycle freon from existing sources. As of 2002, freon cost about $85 per lb ($187 per kg). Freon is most frequently sold in 12 ounce (340 g) cans and 30 pound (13.6 kg) canisters.

Freon 12 ® (also known as R-12) was a popular refrigerant before it was banned. The chemical formula is CCl₂F₂ and its proper chemical name is dichlorodifluoromethane. When people refer to freon without specifying a number, it is likely that they mean freon-12.

Suva 134a ® (also known as R-134 or R-134a) is the most common replacement for R-12. Unlike R-12, which is a chlorofluorocarbon, R-134 is a hydrofluorocarbon. The chemical formula is CH₂FCF₃ and the proper chemical name 1,1,1,2-tetrafluoroethane.

	Freon 41	fluoromethane
R-11	CFC-11	trichlorofluoromethane
R-12	CFC-12	dichlorodifluoromethane
R-13	CFC-13	chlorotrifluoromethane
R-22	HCFC-22	chlorodifluoromethane
R-23	HFC-23	trifluoromethane
R-113	CFC-113	trichlorotrifluoroethane
R-114	CFC-114	1,2-dichloro-1,1,2,2-tetrafluoroethane
R-115	CFC-115	1-chloro-1,1,2,2,2-pentafluoroethane
R-116	CFC-116	hexachloroethane
R-134a	HFC-134a	1,1,1,2-tetrafluoroethane
R-227ea	HFC-227ea	1,1,1,2,3,3,3-heptafluoropropane

Freon in copper tubing open to the environment can turn into phosgene gas after coming in contact with extreme heat, such as, while brazing or in a fire situation. Phosgene is a substance that was used as a chemical weapon in World War I. Low exposure can cause irritation, but high levels cause fluid to collect in the lungs, possibly resulting in death.

See also

• Halon
• CFC

External links

• Numbering Scheme for Ozone-Depleting Substances and their Substitutes
• Class I Ozone-Depleting Substances