Dichlorodifluoromethane

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Dichlorodifluoromethane
Chemical name	Dichlorodifluoromethane
Other names	R-12 CFC-12 Freon 12 P-12 Propellant 12
Chemical formula	CCl2F2
Molecular mass	120.9135064 g/mol
CAS number	[75-71-8]
Density	1.49 g/cm3 at -30 °C
Melting point	-156 °C
Boiling point	-30 °C
SMILES	ClC(F)(Cl)F
NFPA 704	0 1 0
Disclaimer and references

Dichlorodifluoromethane (R-12), usually sold under the brand name Freon-12, is a chlorofluorocarbon halomethane used as a refrigerant and aerosol spray propellant until its manufacture was discontinued in 1995, due to concerns about damage to the ozone layer. The ozone depletion potential of R-12 is 0.82, which is relatively high.

However, as of 2005, it is still found along with trichloromonofluoromethane in aerosols, for example USP-approved Albuterol.

[edit] Retrofitting

R-12 was primarily used in automobiles produced prior to 1994. For older vehicles retrofits to R-134a (1,1,1,2-tetrafluoroethane) is generally recommended. Retrofits usually include a complete flushing of the air conditioning system to remove the oil. The oils used for R12 and R134a are not generally compatible, although some oils designed for conversion to R134 are advertised as compatible with residual R12. Additionally a new compressor, expansion valve, and dryer may be needed. In some cases, all new rubber hoses are needed. These components are usually aftermarket products which are certified as R-134a compatiable. Some car manufactures offer OEM replacement options for older R-12 air conditioning systems.

[edit] Alternative refrigerants

Below is a list of known "drop in" alternatives to R-12.

• Freeze12
• R-416a
• R-414B
• R-406
• HC-12a

[edit] External links

• Overview of Freon-12 and some of its environmental problems
• Links to external chemical sources.

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