1,1-Dichlorotetrafluoroethane

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. ==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. 1,1-Dichlorotetrafluoroethane does not ignite in air. 1,1-Dichlorotetrafluoroethane reacts with alkali metals, alkaline earths and aluminium. ==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. ==Atmosphere==

The ozone depletion potential of 1,1-dichlorotetrafluoroethane is 0.72. The estimated lifetime in the atmosphere is about 100 years. 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==