The CFC-Ozone Issue: Progress on the Development of Alternatives to CFCs

Abstract

Chlorofluorocarbons (CFCs) are now believed to be major contributors to the seasonal ozone depletion over the Antarctic continent. However, because they are so important to many aspects of Modern society, it would be irresponsible to immediately cease their production. The identification of suitable substitutes is difficult when issues such as toxicity, flammability, cost, environmental impact, and physical properties are considered. Several candidates that meet these criteria have been selected by the industry and significant research and development programs are under way to commercialize them. Unlike the simple, fully halogenated CFCs, which can only be made in the single step, there are many potentially viable routes to the alternatives, but these will require significant improvements in catalysis. Many other important issues such as materials compatibility, energy efficiency, the needs of developing countries, and the product life cycle of the alternatives need to be resolved before a timely transition to substitutes can be accomplished.

Designing safer chemicals: predicting the rates of metabolism of halogenated alkanes.

“…oped as replacements for the ozone-depleting chlorofluorocarbons (6). The metabolic fate and toxicity of H(C)FCs have been reviewed.…”

Continued increase of CFC-113a (CCl<sub>3</sub>CF<sub>3</sub>) mixing ratios in the global atmosphere: emissions, occurrence and potential sources

“…There are two main routes for making HFC134a (Manzer, 1990). The first begins with CFC-113 being isomerised to form CFC-113a, which is then fluorinated to produce CFC-114a (CF3CCl2F), the latter is then hydrogenated to produce HFC-134a (Manzer, 1990).…”

“…There are two main routes for making HFC134a (Manzer, 1990). The first begins with CFC-113 being isomerised to form CFC-113a, which is then fluorinated to produce CFC-114a (CF3CCl2F), the latter is then hydrogenated to produce HFC-134a (Manzer, 1990). The other production method involves the reaction of hydrogen fluoride with trichloroethylene to form HCFC-133a and HFC-134a (Manzer, 1990).…”

The kidney as a novel target tissue for protein adduct formation associated with metabolism of halothane and the candidate chlorofluorocarbon replacement 2,2‐dichloro‐1,1,1‐trifluoroethane

“…The data suggest that metabolism and concomitant CF,CO-protein formation of halothane or of candidate CFC replacements like HCFC 123 is not restricted to the liver but also takes place in the kidney. Furthermore, an in vitro system for CF,CO-protein formation has been developed and used to show that protein-centered and glutathione-centered nucleophilic sites compete for intermediates of metabolism of halothane or of HCFC 123.Chlorofluorocarbons (CFCs) have a high ozone-depleting potential [I] and are held responsible for seasonal depleting of stratospheric ozone layers over the Antarctic continent [2]. Ozone destruction leads to an increase of the amount of Correspondence to J. Gut,…”

“…Chlorofluorocarbons (CFCs) have a high ozone-depleting potential [I] and are held responsible for seasonal depleting of stratospheric ozone layers over the Antarctic continent [2]. Ozone destruction leads to an increase of the amount of Correspondence to J. Gut,…”