L-Bromo-2,2-difluoroethane

Difluora-l-bromoethane. See l-Bromo-2,2-difluoroethane in this Section... 

Dibromofltjoroethane and l-Bromo-2,2-difluoroethane. By a procedure analogous to that just described, 1,2,2-tribrojnoethane was converted to the mono- and di-fluoro derivatives. The reaction temperature had to be lower for good results. At 0°, the yield of fnixed products was 50% at — 20°, 60-65%. At higher temperatures the yield was only 30%. The boiling points are 121° and 57°, respectively. 

Preparation. Thermal elimination of HCl from l-chloro-l,l-difluoroethane (HCFC-142b) [75-68-3] is the principal industrial route to VDF covered by numerous patents (8—19). Dehydrohalogenation of l-bromo-l,l-difluoroethane (20), or 1,1,1-trifluoroethane (HFC-143a) (21—25), or dehalogenation of l,2-dichloro-l,l-difluoroethane (26—28) are investigated alternative routes (see Fluorine compounds, organic-fluorinated aliphatic compounds). 

Dehydrohalogenation of l-bromo-l,l-difluoroethane or 1,1,1-trifluo-roethane, or dehalogenation of l,2-dichloro-l,l-difluoroethane are alternative routes. 

Difluoroethanol is prepared by the mercuric oxide cataly2ed hydrolysis of 2-bromo-l,l-difluoroethane with carboxyHc acid esters and alkaH metal hydroxides ia water (27). Its chemical reactions are similar to those of most alcohols. It can be oxidi2ed to difluoroacetic acid [381-73-7] (28) it forms alkoxides with alkaH and alkaline-earth metals (29) with alkoxides of other alcohols it forms mixed ethers such as 2,2-difluoroethyl methyl ether [461-57-4], bp 47°C, or 2,2-difluoroethyl ethyl ether [82907-09-3], bp 66°C (29). 2,2-Difluoroethyl difluoromethyl ether [32778-16-8], made from the alcohol and chlorodifluoromethane ia aqueous base, has been iavestigated as an inhalation anesthetic (30,31) as have several ethers made by addition of the alcohol to various fluoroalkenes (32,33). Methacrylate esters of the alcohol are useful as a sheathing material for polymers ia optical appHcations (34). The alcohol has also been reported to be useful as a working fluid ia heat pumps (35). The alcohol is available ia research quantities for ca 6/g (1992). 

Bromo-l-chloro-l,l-difluoroethane (3) is prepared from l,2-dibromo-l,l-dichloroethane (1) in good yield when the fluorination reaction with antimony(III) fluoride/antimony(V) chloride is conducted in two steps. 

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