Tetrachloro-1,2-difluoroethane is a chlorofluorocarbon known as Freon 112, CFC-112 or R-112. It has a symmetrical structure CCl2FCCl2F and so can be called symmetrical tetrachlorodifluoroethane. "Symmetrical" may also be abbreviated to "s-" or "sym-". In contrast an asymmetrical isomer has formula CCl3CClF2.
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| Names | |
|---|---|
| IUPAC name 1,1,2,2-tetrachloro-1,2-difluoroethane | |
| Other names 1,1,2,2-Tetrachloro-1,2-difluoroethane; 1,2-Difluorotetrachloroethane; Freon 112; 1,2-Difluoro-1,1,2,2-tetrachloroethane; ; sym-Tetrachlorodifluoroethane; R 112; CFC-112; 1,1,2,2-Tetrachlorodifluoroethane; | |
| Identifiers | |
3D model (JSmol) | |
| ChEMBL | |
| ChemSpider | |
| ECHA InfoCard | 100.000.851 |
| EC Number |
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PubChem CID | |
| RTECS number |
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| UNII | |
| UN number | 1078 |
CompTox Dashboard (EPA) | |
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| Properties | |
| C2Cl4F2 | |
| Molar mass | 203.82 g·mol−1 |
| Appearance | clear liquid or white solid |
| Density | 1.634 g/mL |
| Melting point | 23.8 °C (74.8 °F; 296.9 K)[1] |
| Boiling point | 92.8 °C (199.0 °F; 365.9 K)[1] |
| 0.012% | |
Refractive index (nD) | 1.4130 |
| Hazards | |
| GHS labelling: | |
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| Warning | |
| H315, H320 | |
| P264, P264+P265, P280, P302+P352, P305+P351+P338, P321, P332+P317, P337+P317, P362+P364 | |
| Related compounds | |
Related compounds | CFC-112a |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). | |
Production
CFC-112 can be made in a reaction with hydrogen fluoride with hexachloroethane or tetrachloroethane with extra chlorine. This reaction occurs with an aluminium fluoride catalyst with some extra iron, nickel and chromium at 400°C. With the extra metal in the catalyst yield of the isomer can be 98% compared with the unsymmetrical isomer.[2]
Mixed with perfluorooctane, it is a solvent for polydimethylsiloxane.[3]
CFC-112 can be prepared as a mixture with other hydrochlorofluorocarbons from trichloroethylene and anhydrous hydrogen fluoride when electric current is passed through.[4]
When CFC-11 is packaged with alcohol in a metal container, a free radical reaction can result in production of CFC-112.[5]
Properties
Critical properties are critical temperature 278°C, critical pressure 4.83 MPa at a density of 0.754 g/cc.[1]
Tetrachloro-1,2-difluoroethane is not flammable.[5]
Tetrachloro-1,2-difluoroethane, like other chlorofluorocarbon compounds reacts violently with sodium, potassium or barium.[5]
Tetrachloro-1,2-difluoroethane is not very toxic, and the lethal dose is estimated at 25 g/kg. It is not carcinogenic.[5]
Use
Tetrachlorodifluoroethane (mixture of isomers) has been used as a veterinary medicine to treat parasites such as liver fluke in sheep (Fasciola hepatica).[6]
MIL-C-8638 is a military specification for a cleaning solvent that contained tetrachlorodifluoroethane, trichlorotrifluoroethane, and isopropyl alcohol. It was used to clean aircraft oxygen systems.[7]
Tetrachlorodifluoroethane can be used as an intermediate in the manufacture of tetrachloroethylene.[8]
Atmosphere
In the atmosphere of Earth, anthropogenic tetrachloro-1,2-difluoroethane has been found to occur. Between 2017 and 2020 levels, were about 0.52 parts per trillion (ppt). Levels rose from the 1970s till about 1995.[9]