| Chemical Abstract Number (CAS #) |
75718
|
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| CASRN |
75-71-8 |
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| Synonyms | Dichlorodifluoromethane |
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Methane, dichlorodifluoro- | CFC 12 |
| Analytical Methods |
EPA Method 502.2 |
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EPA Method 524.2 |
EPA Method 601 |
EPA Method 8010 |
EPA Method 8021 |
EPA Method 8260 |
| Molecular Formula | CCl2F2 |
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Link to the National Library of Medicine's Hazardous Substances
Database for more details
on this compound. |
| Use | LEAK-DETECTING AGENT; FREEZING OF FOODS BY DIRECT CONTACT; SRP:
FORMER USE CHILLING OF COCKTAIL GLASSES
TO PREPARE FROZEN TISSUE SECTIONS
In manufacture of aerosols for cosmetics, pharmaceuticals, insecticides, paints, adhesives, and
cleaners SRP: Former use/. Use in manufacture of and extensive use as a refrigerant in home
and commercial applications. Used as a blowing agent for cellular polymers, a solvent or
diluent in fumigants for food sterilization, in paints and varnish removers, and in polymerization
processes. Used as a foaming agent in fire extinguishing aerosols, for surfactants. Used in
water purification, copper and aluminum purification, petroleum recovery, and in manufacture of
glass bottles. Used in regulating devices for leak detection, in thermal expansion valves, used in
manufacture of materials for electrical applications as insulators and generator windings. Used in
organic synthesis of Freons and a polymerization catalyst, used as a working fluid for heat
pumps and in hydraulic fluids.
IN VARIOUS "SKIN FREEZES" BY AEROSOL APPLICATION, AS PROPELLANT FOR
ANTIBIOTIC POWDERS, MASTITIS FORMULATIONS, ETC, & FOR ADMIXTURE TO
OTHER GASES SUCH AS ETHYLENE OXIDE TO MAKE THEM NON-FLAMMABLE.
Used in refrigeration systems.
MECHANICAL VAPOR COMPRESSION SYSTEMS USE FLUOROCARBONS FOR
REFRIGERATION & AIR CONDITIONING & ACCOUNT FOR MAJORITY OF
REFRIGERATION CAPABILITY IN US. FLUOROCARBONS ARE USED AS
REFRIGERANTS IN HOME APPLIANCES, MOBILE AIR CONDITIONING UNITS,
RETAIL FOOD REFRIGERATION SYSTEMS & CHILLERS. FLUOROCARBONS
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| Consumption Patterns | Refrigerant (46%), foam blowing agent (20%), solvent (16%), fluoropolymers (7%),
other (4%), export (7%). Solvent use is mainly in the aerospace and electronic industries (1981).
Blowing agent 71%; refrigeration 6%; aerosol 5%; and miscellaneous 18%.
Blowing agent 11%; mobile air-conditioning 37%; retail food refrigeration 4%; chillers 1%; home
refrigerators 2%; aerosol 4%; micellaneous 10%; unallocated 31% (1986).
FREON 12 IS THE MOST WIDELY USED REFRIGERANT WITH TYPICAL USES IN
DOMESTIC, COMMERCIAL AND INDUSTRIAL SYSTEMS AND AUTOMOBILE
AIR-CONDITIONING (1984). FREON 12
REFRIGERANTS, 39%; FOAM BLOWING AGENTS, 17%; SOLVENTS, 14%;
FLUOROPOLYMERS, 14%; STERILANT GAS, 2%; AEROSOL PROPELLANTS, 2%;
FOOD FREEZANT, 1%; OTHER, 8%; EXPORTS, 3% (1985) FLUOROCARBONS (1986)]
Refrigeration/air conditioning, 43%; foam blowing agents, 20%; polymer precursors, 13%;
solvent cleaning, 12% aerosol propellants, 2%; medical equipment sterilization, 3%; other, 7%.
(1991). Estimates are for CFC-11,-12,-113,-114,-115 and HCFC-22 only
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| Apparent Color | COLORLESS GAS ; LIQUEFIED COMPRESSED GAS
|
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| Odor | PRACTICALLY ODORLESS; FAINT, ETHER-LIKE ODOR IN HIGH CONCN
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| Boiling Point | -29.8 DEG C AT 760 MM HG
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| Melting Point | -158 DEG C
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| Molecular Weight | 120.91
|
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| Density | 1.486 AT -29.8 DEG C
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| Environmental Impact | Dichlorodifluoromethane (Freon 12) is produced in large quantities and will be released to
the environment as emissions during its production, storage, transport, and use as a refrigerant,
foam blowing agent, solvent, and chemical intermediate in the production of fluoropolymers. All
of the dichlorodifluoromethane that is produced is eventually lost as emissions and the levels of
this chemical has been building up in the atmosphere. If released on land, dichlorodifluoromethane
will leach into the ground and volatilize from the soil surface. No degradative processes are
known to occur in the soil. Dichlorodifluoromethane is also stable in water and the only removal
process will be volatilization. It can enter water bodies from the atmosphere and the concn of
dichlorodifluoromethane in the surface water rapidly reaches equilibrium with the concn in the air.
Ocean currents also carry the chemical long distances and many kilometers below the surface.
Dichlorodifluoromethane is extremely stable in the troposphere and will disperse over the globe
and diffuse slowly into the stratosphere where it will be lost by photolysis. In this process,
chlorine atoms are released that attack ozone. The realization that certain chlorofluorocarbons can
accumulate in the upper atmosphere and deplete the earth's ozone layer has resulted in restrictions
on the uses of these chemicals. This is particularly true in the case of dichlorodifluoromethane
since it is used in such large quantities and is so stable and effective in destroying ozone. General
population exposure occurs by inhalation of dichlorofluoromethane in ambient air. Occupational
exposure may occur via inhalation or dermal contact.
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| Environmental Fate | Due to the high vapor pressure of dichlorodifluoromethane, volatilization to the
atmosphere is quite rapid. It does not react readily with hydroxyl radicals, nor does it
photodissociate in the troposphere since it exhibits no absorption of light greater than 200 nm.
In the stratosphere, dichlorodifluoromethane is broken down by the absorption of higher energy,
shorter wavelength ultraviolet light.
TERRESTRIAL FATE: If released on land, dichlorodifluoromethane will leach into the ground
and volatilize from the soil surface. No degradative processes are known to occur in the soil.
AQUATIC FATE: Dichlorodifluoromethane is persistent in natural waters . It primarily enters
bodies of water from the atmosphere. Since it is extremely stable in the water as well as in the
atmosphere and does not adsorb appreciably to sediment, the only removal process will be
volatilization. The concn of dichlorodifluoromethane in surface water would be expected to reach
solubility equilibrium with the atmosphere relatively rapidly . Ocean surface water
measurements in the Eastern Pacific show that a rough equilibrium with air concn exists .
Accordingly, the chemical has been used as a tracer for ocean circulation and mixing. Model
calculations have resulted in the time scale for deep convection mixing in the Greenland and
Norwegian Seas to be about 40 years and the lateral mixing between the depths of these seas as
20-30 yr .
ATMOSPHERIC FATE: Dichlorodifluoromethane is extremely stable in the troposphere and will
disperse over the globe and diffuse slowly into the stratosphere where it will be photolyzed by the
short wavelength UV radiation. It will also be removed from the atmosphere by dry deposition.
This can be estimated assuming a deposition velocity of 0.1 cm/s to be 0.76 million lbs/year on the
U.S.(1,SRC). However, the chemical does not degrade in water or soil and the chemical will
volatilize back into the atmosphere. The combined stability, deposition, and volatilization will
result in a more or less equal distribution of dichlorodifluoromethane in bodies of water all over
the earth as well as in the atmosphere.
ATMOSPHERIC FATE: THEIR USE FOR AEROSOL SPRAYS WAS PROHIBITED
BECAUSE OF THEIR DEPLETING EFFECT ON STRATOSPHERIC OZONE.
/CHLOROFLUOROCARBONS
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| Drinking Water Impact | GROUNDWATER: Dichlorodifluoromethane was detected, but not quantified in
groundwater under 6 of 13 municipal landfills in Minnesota with suspected leakage but not in the
groundwater under 7 other municipal landfills .
SURFACE WATER: Of the 696 stations reporting dichlorodifluoromethane in ambient waters in
EPA's STORET database, 1.0% contained detectable levels of the chemical .
Dichlorodifluoromethane was detected, but not quantified, in the open waters of Lake Erie .
The average concn of dichlorodifluoromethane in surface water at two stations in the Greenland
and Norwegian Sea was 218 and 187 pbb, respectively . The concn decreased with depth over
many km in the Greenland Sea and was relatively constant in the upper 0.4 km in the Norwegian
Sea before decreasing . The deep water concns of dichlorodifluoromethane in these seas were
37 and 18 ppb .
EFFL: Of the 1,144 stations reporting dichlorodifluoromethane in effluents in EPA's STORET
database, 1.6% contained detectable levels of the chemical . No dichlorodifluoromethane was
found in the effluent of a large community septic tank (detection limit 0.7 ppb) . In the National
Urban Runoff Program in which samples of runoff were collected from 19 cities (51 catchments)
in the U.S., no dichlorodifluoromethane was found in any samples . Leachate from 2 of 6
municipal landfills tested in Minnesota had detectable quantities of dichlorodifluoromethane .
Leachate from 1 out of 5 landfills in Wisconsin contained 180 ppb of the chemical .
Dichlorodifluoromethane was emitted from a simulated landfill composed of municipal refuse and
wastewater sludges .
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