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1,1-Dichlorotetrafluoroethane

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1,1-Dichlorotetrafluoroethane
Names
IUPAC name 1,1-dichloro-1,2,2,2-tetrafluoroethane
Other names R114a; CFC-114a
Identifiers
CAS Number
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.006.159 Edit this at Wikidata
EC Number
  • 206-774-8
PubChem CID
UNII
CompTox Dashboard (EPA)
InChI
  • InChI=1S/C2Cl2F4/c3-1(4,5)2(6,7)8Key: BAMUEXIPKSRTBS-UHFFFAOYSA-N
SMILES
  • C(C(F)(Cl)Cl)(F)(F)F
Properties
Chemical formula C2Cl2F4
Molar mass 170.92 g·mol
Density 1.455 g/cu cm (as a liquid under pressure)
Melting point −56.6 °C (−69.9 °F; 216.6 K)
Boiling point 3.4 °C (38.1 °F; 276.5 K)
Solubility in water 137 mg/L
Solubility benzene, diethyl ether, ethanol
log P 2.78
Vapor pressure 1640 mm Hg
Refractive index (nD) 1.3092 at 0 °C
Hazards
GHS labelling:
Pictograms GHS07: Exclamation markGHS09: Environmental hazard
Signal word Danger
Hazard statements H335, H336, H370, H420
Precautionary statements P260, P261, P264, P270, P271, P304+P340, P308+P316, P319, P321, P403+P233, P405, P501, P502
Related compounds
Related compounds CFC-114
Except where otherwise noted, data are given for materials in their standard state (at 25 °C , 100 kPa). Infobox references
Chemical compound

1,1-Dichlorotetrafluoroethane is a chlorofluorocarbon also known as CFC-114a or R114a by American Society of Heating, Refrigerating, and Air Conditioning Engineers. It has two chlorine atoms on one carbon atom and none on the other. It is one of two isomers of dichlorotetrafluoroethane, the other being 1,2-dichlorotetrafluoroethane, also known as CFC-114.

Formation

1,1-Dichlorotetrafluoroethane can be made free from other isomers by reacting trichlorotrifluoroethane (CFC-113 or CFC-113a) with antimony pentachloride. Trichlorotrifluoroethane can also be reacted with sulfur tetrafluoride or dichlorodifluoromethane with aluminium fluoride catalyst to yield 1,1-dichlorotetrafluoroethane. The use of aluminium in the catalyst favours the asymmetric molecules.

It can also be made in a reaction of tetrachloroethylene with hydrogen fluoride and chlorine, but this results in a mixture.

Fluorinating 1,2-dichlorodifluoroethylene with fluorine produces a small amount of 1,1-dichlorotetrafluoroethane, but mostly tetrachlorotetrafluorobutene and some other chloroflurocarbons, so is not a good way.

Properties

1,1-Dichlorotetrafluoroethane has a close boiling point (3.6°C) to the isomer 1,2-dichlorotetrafluoroethane (3.8°C), and so is difficult to separate by distillation. Also in a gas chromatograph, it is hard to distinguish from the symmetric 1,2 isomer.

Critical properties include critical temperature 145.7°C, critical pressure 4.92 Mpa and critical density of 0.82 g/ml.

1,1-Dichlorotetrafluoroethane does not ignite in air.

Reactions

1,1-Dichlorotetrafluoroethane reacts with hydrogen when heated at 300 to 600°C with a palladium catalyst in a hydrodechlorination. The main reaction product is 1,1,1,2-tetrafluoroethane, but also 1-chloro-1,2,2,2-tetrafluoroethane (CF3CHClF) and 1,1,1-trifluoroethane are formed.

1,1-Dichlorotetrafluoroethane reacts with alkali metals, alkaline earths and aluminium.

When heated with hydrogen over a nickel catalyst, 1,1-dichlorotetrafluoroethane is dechlorinated with replacement by hydrogen to yield a mixture of CF3CHClF and the dimer CF3CClFCClFCF3.

Use

CFC-114a was used in aerosol propellants, blowing agents, and in polyolefin foams. There was also use in refrigerants. Production was banned in by the Montreal Protocol.

CFC-114a is a possible intermediate in the production of HFC-134a which can be produced by hydrogenation.

Atmosphere

Mixing ratio of CFC-114a in air (red). Also CFC-114 in black

The ozone depletion potential of 1,1-dichlorotetrafluoroethane is 0.72. The estimated lifetime in the atmosphere is about 100 years. The radiative efficiency is 0.28 Wmppb. Global warming potential in 20 years is 6750. The atmospheric concentration of CFC-114a is not usually measured separately from CFC-114 due to difficulties in distinguishing them apart.

In 1978 atmospheric levels of CFC-114a were 0.35 ppt. By 2020 the level was up to 1.13 ppt. CFC-114a appears to be emitted into the atmosphere is South East Asia.

The atmospheric natural destruction of CFC-114a is by reaction with atomic oxygen, or breakup by ultraviolet light. As of 2014 about 250 tons per year of CFC-114a were being put into the atmosphere.

References

  1. "1,1-Dichloro-1,2,2,2-tetrafluoroethane". pubchem.ncbi.nlm.nih.gov.
  2. Deiters, Ulrich K (May 1997). "Some remarks on the nomenclature of refrigerants". Fluid Phase Equilibria. 132 (1–2): 265–270. Bibcode:1997FlPEq.132..265D. doi:10.1016/S0378-3812(96)03232-3.
  3. ^ Gumprecht, William Henry; Longoria, John Mark; Christoph, Frank J. (8 May 1991). "Process for manufacture of 1,1-dichlorotetrafluoroethane".
  4. Bozorgzadeh, H; Kemnitz, E; Nickkho-Amiry, M; Skapin, T; Winfield, J.M (January 2001). "Conversion of 1,1,2-trichlorotrifluoroethane to 1,1,1-trichlorotrifluoroethane and 1,1-dichlorotetrafluoroethane over aluminium-based catalysts". Journal of Fluorine Chemistry. 107 (1): 45–52. Bibcode:2001JFluC.107...45B. doi:10.1016/S0022-1139(00)00350-X.
  5. Haszeldine, R. N. (1952). "849. Fluoro-olefins. Part I. The synthesis of hexafluorobuta-1 : 3-diene". Journal of the Chemical Society (Resumed): 4423. doi:10.1039/JR9520004423.
  6. ^ Chen, Limin; Makide, Yoshihiro; Tominaga, Takeshi (1994). "Determination of 1,2-dichlorotetrafluoroethane (CFC-114) Concentration in the Atmosphere". Chemistry Letters. 23 (3): 571–574. doi:10.1246/cl.1994.571.
  7. ^ Bruno, Thomas J. (1990). Spectroscopic Library for Alternative Refrigerant Analysis. U.S. Department of Commerce, National Institute of Standards and Technology. pp. 25–27.
  8. Karpinski, Zbigniew; Early, Kintu; d'Itri, Julie L. (December 1996). "Catalytic Hydrodechlorination of 1,1-Dichlorotetrafluoroethane by Pd/Al2O3". Journal of Catalysis. 164 (2): 378–386. doi:10.1006/jcat.1996.0394.
  9. Tomioka, Satoshi; Mori, Tohru; Ueda, Wataru; Morikawa, Yutaka; Ikawa, Tsuneo (October 1991). "A Novel Hydrodechlorinative Dimerization of Chlorofluorocarbons over Supported Ni Catalysts". Chemistry Letters. 20 (10): 1825–1826. doi:10.1246/cl.1991.1825.
  10. ^ Laube, Johannes C.; Mohd Hanif, Norfazrin; Martinerie, Patricia; Gallacher, Eileen; Fraser, Paul J.; Langenfelds, Ray; Brenninkmeijer, Carl A. M.; Schwander, Jakob; Witrant, Emmanuel; Wang, Jia-Lin; Ou-Yang, Chang-Feng; Gooch, Lauren J.; Reeves, Claire E.; Sturges, William T.; Oram, David E. (9 December 2016). "Tropospheric observations of CFC-114 and CFC-114a with a focus on long-term trends and emissions". Atmospheric Chemistry and Physics. 16 (23): 15347–15358. Bibcode:2016ACP....1615347L. doi:10.5194/acp-16-15347-2016. S2CID 54195362.
  11. Suh, Dong Jin; Park, Tae-Jin; Lee, Byung-Gwon; Park, Kun-You (January 1996). "Synthesis of HFC-134a by isomerization and hydrogenation". Korean Journal of Chemical Engineering. 13 (1): 75–81. doi:10.1007/BF02705892. S2CID 97614597.
  12. ^ Davis, Maxine E.; Bernard, François; McGillen, Max R.; Fleming, Eric L.; Burkholder, James B. (1 July 2016). "UV and infrared absorption spectra, atmospheric lifetimes, and ozone depletion and global warming potentials for CCl<sub>2</sub>FCCl<sub>2</sub>F (CFC-112), CCl<sub>3</sub>CClF<sub>2</sub> (CFC-112a), CCl<sub>3</sub>CF<sub>3</sub> (CFC-113a), and CCl<sub>2</sub>FCF<sub>3</sub> (CFC-114a)". Atmospheric Chemistry and Physics. 16 (12): 8043–8052. Bibcode:2016ACP....16.8043D. doi:10.5194/acp-16-8043-2016. hdl:1983/df193a7b-14de-427c-a539-238701f9e3b3. S2CID 102078043.
  13. Western, Luke M.; et al. (3 April 2023). "Global increase of ozone-depleting chlorofluorocarbons from 2010 to 2020". Nature Geoscience. 16 (4): 309–313. Bibcode:2023NatGe..16..309W. doi:10.1038/s41561-023-01147-w. hdl:1983/9e103fef-e61c-49c7-a1a3-902540ec1d7c. S2CID 257941769.
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