Tetrachloro-1,2-difluoroethane

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.

Tetrachloro-1,2-difluoroethane

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
CAS Number	76-12-0
3D model (JSmol)	Interactive image
ChEMBL	ChEMBL3186694
ChemSpider	6187
ECHA InfoCard	100.000.851
EC Number	200-935-6
PubChem CID	6427
RTECS number	KI1420000
UNII	H155PU1V8F
UN number	1078
CompTox Dashboard (EPA)	DTXSID5026091
InChI InChI=1S/C2Cl4F2/c3-1(4,7)2(5,6)8 Key: UGCSPKPEHQEOSR-UHFFFAOYSA-N
SMILES C(C(F)(Cl)Cl)(F)(Cl)Cl
Properties
Chemical formula	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]
Solubility in water	0.012%
Refractive index (nD)	1.4130
Hazards
GHS labelling:
Pictograms
Signal word	Warning
Hazard statements	H315, H320
Precautionary statements	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). Infobox references

Production

CFC-112 can be made in a reaction of hexachloroethane or tetrachloroethane with hydrogen fluoride and extra chlorine. This reaction is catalysed by aluminium fluoride with some extra iron, nickel and chromium at 400°C. The extra metal in the catalyst yields 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 until about 1995.^[9]