1,1,2-Trichloro-1,2,2-trifluoroethane
1,1,2-Trichloro-1,2,2-trifluoroethane, also called trichlorotrifluoroethane (often abbreviated as TCTFE) or CFC-113, is a chlorofluorocarbon. It has the formula Cl2FC−CClF2. This colorless, volatile liquid is a versatile solvent.[5]
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| Names | |||
|---|---|---|---|
| Preferred IUPAC name 1,1,2-Trichloro-1,2,2-trifluoroethane | |||
| Other names Arklone P CFC-113 Freon 113 Frigen 113 TR Freon TF Valclene 1,1,2-trichlorotrifluoroethane TCTFE Solvent 113 | |||
| Identifiers | |||
3D model (JSmol) | |||
| ChEMBL | |||
| ChemSpider | |||
| ECHA InfoCard | 100.000.852 | ||
PubChem CID | |||
| UNII | |||
CompTox Dashboard (EPA) | |||
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| Properties | |||
| CClF2CCl2F | |||
| Molar mass | 187.37 g·mol−1 | ||
| Appearance | Colorless liquid | ||
| Odor | like carbon tetrachloride[1] | ||
| Density | 1.56 g/mL | ||
| Melting point | −35 °C (−31 °F; 238 K) | ||
| Boiling point | 47.7 °C (117.9 °F; 320.8 K) | ||
| 170 mg/L | |||
| Vapor pressure | 285 mmHg (20 °C)[1] | ||
| Thermal conductivity | 0.0729 W m−1 K−1 (300 K)[2] | ||
| Hazards | |||
| Lethal dose or concentration (LD, LC): | |||
LCLo (lowest published) | 250,000 ppm (mouse, 1.5 hr) 87,000 (rat, 6 hr)[3] | ||
| NIOSH (US health exposure limits): | |||
PEL (Permissible) | TWA 1000 ppm (7600 mg/m3)[1] | ||
REL (Recommended) | TWA 1000 ppm (7600 mg/m3) ST 1250 ppm (9500 mg/m3)[1] | ||
IDLH (Immediate danger) | 2000 ppm[1] | ||
| Hazards | |||
| GHS labelling:[4] | |||
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| Warning | |||
| NFPA 704 (fire diamond) | |||
| Safety data sheet (SDS) | https://datasheets.scbt.com/sc-251541.pdf | ||
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). | |||
Production
CFC-113 can be prepared from hexachloroethane and hydrofluoric acid:[6]
This reaction may require catalysts such as antimony, chromium, iron and alumina at high temperatures.[7]
Another synthesis method uses HF on tetrachloroethylene instead.[8]
Atmospheric reactions
CFC-113 is a very unreactive chlorofluorocarbon. It remains in the atmosphere about 90 years,[9] sufficiently long that it will cycle out of the troposphere and into the stratosphere. In the stratosphere, CFC-113 can be broken up by ultraviolet radiation (where sunlight in the 190-225 nm (UV) range), generating chlorine radicals (Cl•), which initiate degradation of ozone requiring only a few minutes:[10][11]
- CClF2CCl2F → C2F3Cl2 + Cl•
- Cl• + O3 → ClO• + O2
This reaction is followed by:
- ClO• + O → Cl• + O2
The process regenerates Cl• to destroy more O3. The Cl• will destroy an average of 100,000 O3 molecules during its atmospheric lifetime of 1–2 years. In some parts of the world, these reactions have significantly thinned the Earth's natural stratospheric ozone layer that shields the biosphere against solar UV radiation; increased UV levels at the surface can cause skin cancer or even blindness.[12]
Uses
CFC-113 was one of the most heavily produced CFCs. In 1989, an estimated 250,000 tons were produced.[5] It has been used as a cleaning agent for electrical and electronic components.[12] CFC-113’s low flammability and low toxicity made it ideal for use as a cleaner for delicate electrical equipment, fabrics, and metals. It would not harm the product it was cleaning, ignite with a spark or react with other chemicals.[13] It was used as a dry-cleaning solvent, introduced by Du Pont in March 1961 as "Valclene"[14] and was also marketed as the "solvent of the future" by Imperial Chemical Industries in the 1970s under the tradename Arklone. Others from this series were Perklone (Tetrachloroethylene), Triklone (Trichloroethylene), Methoklone (Dichloromethane) and Genklene (1,1,1-Trichloroethane).[15][16]
CFC-113 is one of the three most popular CFCs, along with CFC-11 and CFC-12.[17]
CFC-113 in laboratory analytics has been replaced by other solvents.[18]
Reduction of CFC-113 with zinc gives chlorotrifluoroethylene:[5]
- CFCl2−CClF2 + Zn → CClF=CF2 + ZnCl2
Dangers
Aside from its immense environmental impacts, Freon 113, like most chlorofluoroalkanes, forms phosgene gas when exposed to a naked flame.[19]