FREON® chlorofluorocarbon products

The formed mixture is composed of trichlorofluoromethane (Freon-11) and dichlorodifluoromethane (Freon-12). These compounds are used as aerosols and as refrigerants. Due to the depleting effect of chlorofluorocarbons (CFCs) on the ozone layer, the production of these compounds may be reduced appreciably. 

The chlorine atoms in the upper atmosphere come from the breakdown of CF2 CI2 and other similar chlorofluorocarbons (CFCs), known commercially as Freons. Production of these compounds was more than one million tons in 1988, largely for use in relrigerators and air conditioners. Once released into the atmosphere, CFCs diffuse slowly upward in the atmosphere until they reach the ozone layer. There, ultraviolet light Irom the sun splits off chlorine atoms. These react with ozone, with dramatic results. Annual ozone decreases have exceeded 50% above Antarctica. The background photo shows the Antarctic hole (red-violet) on September 24, 2003. 

Production of freons or chlorofluorocarbons (CFCs) (chlorofluoromethane and chlorofluoroethanes) began in 1930 and the world production reached 2 billion pounds annually by 1974. 

The chlorofluorocarbon compounds of methane and ethane are collectively known as freons. They are extremely stable, unreactlve, non-toxic, non-corrosive and easily liquefiable gases. Freon 12 (CCI2F2) Is one of the most common freons In Industrial use. It Is manufactured from tetrachloromethane by Swarts reaction. These are usually produced for aerosol propellants, refrigeration and air conditioning purposes. By 1974, total freon production In the world was about 2 billion pounds annually. Most freon, even that used In refrigeration, eventually makes Its way Into the atmosphere where It diffuses unchanged Into the stratosphere. In stratosphere, freon Is able to Initiate radical chain reactions that can upset the natural ozone balance (Unit 14, Class XI). 

Freon is a commercial trademark for a series of fluorocarbon products used in refrigeration and air-conditioning equipment, as aerosol propellants, blowing agents, fire extinguishing agents, and cleaning fluids and solvents. Many types contain chlorine as well as fluorine, and should be called chlorofluorocarbons (CFCs) [85,86]. 

A carbon atom can be bonded to as many as four halogen atoms, so an enormous number of organic halides can exist. Completely fluorinated compounds are known as fluorocarbons or sometimes perfluorocarbons. The fluorocarbons are even less reactive than hydrocarbons. Saturated compounds in which all H atoms have been replaced by some combination of Cl and F atoms are called chlorofluorocarbons or sometimes freons. These compounds were widely used as refrigerants and as propellants in aerosol cans. However, the release of chlorofluorocarbons into the atmosphere has been shown to be quite damaging to the earth s ozone layer. Since January 1978, the use of chlorofluorocarbons in aerosol cans in the United States has been banned, and efforts to develop both controls for existing chlorofluorocarbons and suitable replacements continue. The production and sale of freons have been banned in many countries. 

Freon is a DuPont trademark for certain chlorofluorocarbons other companies related products are known by other names. Typical freons are trichlorofluoromethane,... 

Large quantities of dichlorodifluoromethane and other chlorofluorocarbons ( Freons ) are used as aerosol propellants, and it has been calculated that there is a danger of reducing the earth s protective ozone layer following photolysis to produce chlorine atoms in the upper atmosphere.184 Milstein and Rowland185 have now measured quantum yields of unity for CF2C12 dissociation [reaction (36)] and for appearance of photo-oxidation products in oxygen. Studies of the... 

Both the aerosol sprays and the aerosol foam products originally tended to contain chlorofluorocarbons (CFCs) like Freon as the pressurized propellant phase (which in foam applications becomes the dispersed gas phase). With increasing environmental awareness and concerns, formulation practices have changed in... 

A major concern with chlorofluorocarbons is destruction of the ozone layer (mentioned in"Chemical Connections Freons Tn this chapter).The ozone-consuming reactions are thought to occur through a radical chain mechanism. The production of one radical species derived from a CFC can destroy a large number of ozone molecules before any termination steps occur. 

Measurements over the last several decades have indicated a rapid decrease of stratospheric ozone. This decrease has been most drastic over Antarctica, where the ozone layer is now almost completely absent (Figure 11.17). Stratospheric ozone over the rest of the planet has decreased at a rate of about 6% each year. Each year, we are exposed to increasing levels of harmful UV radiation that are linked with skin cancer and other health issues. While many factors contribute to ozone depletion, it is believed that the main culprits are compounds called chlorofluorocarbons (CFCs). CFCs are compounds containing only carbon, chlorine, and fluorine. In the past they were heavily used for a wide variety of commercial applications, including as refrigerants, propellants, in the production of foam insulation, as fire-flghting materials, and many other useful applications. They were sold under the trade name Freons. ... 

Production of chlorofluoromethanes (and of chlorofluo-roethanes) called chlorofluorocarbons (CFCs) or freons began in 1930. These compounds have been used as refrigerants, solvents, and propellants in aerosol cans. 

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