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.
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.[1]
Mixed with perfluorooctane, it is a solvent for polydimethylsiloxane.[2]
CFC-112 can be prepared as a mixture with other hydrochlorofluorocarbons from trichloroethylene and anhydrous hydrogen fluoride when electric current is passed through.[3]
When CFC-11 is packaged with alcohol in a metal container, a free radical reaction can result in production of CFC-112.
Critical properties are critical temperature 278°C, critical pressure 4.83 MPa at a density of 0.754 g/cc.
Tetrachloro-1,2-difluoroethane is not flammable.[4]
Tetrachloro-1,2-difluoroethane, like other chlorofluorocarbon compounds reacts violently with sodium, potassium or barium.[4]
Tetrachloro-1,2-difluoroethane is not very toxic, and the lethal dose is estimated at 25 g/kg. It is not carcinogenic.[4]
Tetrachlorodifluoroethane (mixture of isomers) has been used as a veterinary medicine to treat parasites such as liver fluke in sheep (Fasciola hepatica).[5]
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.[6]
Tetrachlorodifluoroethane can be used as an intermediate in the manufacture of tetrachloroethylene.[7]
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.[8]