1-Chloro-1,1-difluoroethane
| Names | |
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| Preferred IUPAC name
1-Chloro-1,1-difluoroethane | |
| Other names
Freon 142b; R-142b; HCFC-142b; Chlorodifluoroethane
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| Identifiers | |
3D model (JSmol)
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PubChem CID
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| UNII | |
CompTox Dashboard (EPA)
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| Properties | |
| C2H3ClF2 | |
| Molar mass | 100.49 g·mol−1 |
| Appearance | Colorless gas[1] |
| Melting point | −130.8 °C (−203.4 °F; 142.3 K)[1] |
| Boiling point | −9.6 °C (14.7 °F; 263.5 K)[1] |
| Slight[1] | |
| Hazards | |
| Occupational safety and health (OHS/OSH): | |
Main hazards
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Asphyxiant |
| 632 °C (1,170 °F; 905 K)[1] | |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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1-Chloro-1,1-difluoroethane (HCFC-142b) is a haloalkane with the chemical formula CH3CClF2. It belongs to the hydrochlorofluorocarbon (HCFC) family of man-made compounds that contribute significantly to both ozone depletion and global warming when released into the environment. It is primarily used as a refrigerant where it is also known as R-142b and by trade names including Freon-142b.[2]
Physiochemical properties
[edit | edit source]1-Chloro-1,1-difluoroethane is a highly flammable, colorless gas under most atmospheric conditions. It has a boiling point of −10 °C.[1][3] Its critical temperature is near 137 °C.[4]
Applications
[edit | edit source]HCFC-142b is used as a refrigerant, as a blowing agent for foam plastics production, and as feedstock to make polyvinylidene fluoride (PVDF).[5] It was introduced to replace the chlorofluorocarbons (CFCs) that were initially undergoing a phase-out per the Montreal Protocol, but HCFCs still have a significant ozone-depletion ability. As of year 2020, HCFC's are replaced by non ozone depleting HFCs within many applications.[6]
In the United States, the EPA stated that HCFCs could be used in "processes that result in the transformation or destruction of the HCFCs", such as using HCFC-142b as a feedstock to make PVDF. HCFCs could also be used in equipment that was manufactured before January 1, 2010.[7] The point of these new regulations was to phase-out HCFCs in much the same way that CFCs were phased out. HCFC-142b production in non article 5 countries like the United States was banned on January 1, 2020, under the Montreal Protocol.[6]
Production history
[edit | edit source]According to the Alternative Fluorocarbons Environmental Acceptability Study (AFEAS), in 2006 global production (excluding India and China who did not report production data) of HCFC-142b was 33,779 metric tons and an increase in production from 2006 to 2007 of 34%.[8]
For the most part, concentrations of HCFCs in the atmosphere match the emission rates that were reported by industries. The exception to this is HCFC-142b which had a higher concentration than the emission rates suggest it should.[9]
Environmental effects
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The concentration of HCFC-142b in the atmosphere grew to over 20 parts per trillion by year 2010.[10] It has an ozone depletion potential (ODP) of 0.07.[11] This is low compared to the ODP=1 of trichlorofluoromethane (CFC-11, R-11), which also grew about ten times more abundant in the atmosphere by year 1985 (prior to introduction of HCFC-142b and the Montreal Protocol).
HCFC-142b is also a minor but potent greenhouse gas. It has an estimated lifetime of about 17 years and a 100-year global warming potential ranging 2300 to 5000.[12][13] This compares to the GWP=1 of carbon dioxide, which had a much greater atmospheric concentration near 400 parts per million in year 2020.
See also
[edit | edit source]References
[edit | edit source]- ^ a b c d e f Record in the GESTIS Substance Database of the Institute for Occupational Safety and Health
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- ^ U.S. Government Publishing Office Federal Register 2005 November 4, Protection of Stratospheric Ozone: Notice of Data Availability; Information Concerning the Current and Predicted Use of HCFC-22 and HCFC-142b Pages 67172 - 67174 [FR DOC # 05-22036].
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