CFCs chlorofluorocarbons

One of the chief uses of chloromethane is as a starting material from which sili cone polymers are made Dichloromethane is widely used as a paint stripper Trichloromethane was once used as an inhalation anesthetic but its toxicity caused it to be replaced by safer materials many years ago Tetrachloromethane is the starting mate rial for the preparation of several chlorofluorocarbons (CFCs) at one time widely used as refrigerant gases Most of the world s industrialized nations have agreed to phase out all uses of CFCs because these compounds have been implicated m atmospheric processes that degrade the Earth s ozone layer... 

Chlorofluorocarbons (CFCs). Prior to 1978 most aerosol products contained chlorofluorocarbon propeUants. Since that time, the use of chlorinated fluorocarbons for aerosols has been seriously curtailed. These compounds have been impHcated in the depeletion of the ozone (qv) layer and are considered to be greenhouse gases (see Airpollution Atmospheric modeling). 

Table 3. Physical Properties of Aliphatic Chlorofluorocarbons (CFCs) ...

A leader in the refrigerants industry, we manufacture and supply customers with economical chlorofluorocarbon (CFC) replacements and non-ozone depleting hydrofluorocarbon (HFC) refrigerants for automotive, home, commercial and transportation uses. In the Americas and Asia, you can find these products under the Genetron name and in Europe and the Middle East under Honeywell Refrigerants. 

The other global environmental problem, stratospheric ozone depletion, was less controversial and more imminent. The U.S. Senate Committee Report supporting the Clean Air Act Amendments of 1990 states, Destruction of the ozone layer is caused primarily by the release into the atmosphere of chlorofluorocarbons (CFCs) and similar manufactured substances—persistent chemicals that rise into the stratosphere where they catalyze the destruction of stratospheric ozone. A decrease in stratospheric ozone will allow more ultraviolet (UV) radiation to reach Earth, resulting in increased rates of disease in humans, including increased incidence of skin cancer, cataracts, and, potentially, suppression of the immune system. Increased UV radiation has also been shown to damage crops and marine resources."... 

As you know, most countries are phasing out certain refrigerants to lessen damage to the ozone layer. The chemicals being phased out are chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs). Replacements are hydrofluorocarbons (HFCs) and certain blends. The DuPont web site (www.dupont.com) gives the handy Table I of recommended replacement refrigerants for various applications. 

Another area of potential interest is in refrigerator liners. The move away from the ozone-layer-damaging chlorofluorocarbons (CFCs) to HCFCs in the USA and pentane/cyclopentane blends in Europe has not been without problems. These newer materials have an adverse effect on ABS whereas the nitrile resin appears satisfactory, if more expensive. 

CHLOROFLUOROCARBONS (cFcs) Ofganie substanees eontaining ehlorine and fluorine whieh were... 

The products are available as tablets, capsules, liquids (in the form of solutions, suspensions, emulsions, gels, or injectables), creams (usually oil-in-water emulsions), ointments (usually water-in-oil emulsions), and aerosols, which contain inhalable products or products suitable for external use. Propellants used in aerosols include chlorofluorocarbons (CFCs), which are being phased out. Recently, butane has been used as a propellant in externally applied products. The major manufactured groups include ... 

Chlorofluorocarbons (CFCs) Aliphatic carbon compounds containing both chlorine and fluorine atoms. 

During the 1980s, it became recognized that chlorofluorocarbons (CFCs), widely used as aerosol propellants, are damaging the ozone layer, and aerosol manufacturers were asked to use other propellants. Some... 

The introduction of the chlorofluorocarbon (CFC) fluids in the early 1930s marked the incepuon of the halofluorocarbon industry. Both in terms of tonnage produced and product value, the CFCs have dominated the organofluorocarbon industry and have provided the feedstocks for the development of other fluorocarbon products such as poly(tetrafluoroethylene). 

F. S. Rowland and M. Molina showed that man-made chlorofluorocarbons, CFCs, could catalytically destroy ozone in the stratosphere (Nobel Prize for Chemistry, with P. Crutzen, 1995). 

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