Trifluoroethan

Cm.OROCARBONSANDCm.OROHYDROCARBONS - TRICm OROETHYLENE] (Vol 6) l,2,-Dibromo-l,l,2-trifluoroethane [354-04-1]... 

Trifluoroethanol was first prepared by the catalytic reduction of trifluoroacetic anhydride [407-25-0] (58). Other methods iaclude the catalytic hydrogeaatioa of trifluoroacetamide [354-38-1] (59), the lithium aluminum hydride reductioa of trifluoroacetyl chloride [354-32-5] (60) or of trifluoroacetic acid or its esters (61,62), and the acetolysis of 2-chloro-l,l,l-trifluoroethane [75-88-7] followed by hydrolysis (60). More recently, the hydrogenation of... 

Cyclization. Constmction of ben2otrifluorides from aHphatic feedstocks represents a new technique with economic potential. For example, l,l,l-trichloro-2,2,2-trifluoroethane [354-58-5] and dimethyl itaconate [617-52-7] form 4-methoxy-6-trifluoromethyl-2JT-pyran-2-one [101640-70-4] which is converted to methyl 3-(trifluoromethyi)ben2oate [2557-13-3] ixh. acetjdene or norbomadiene (125). 

A significant development ia trifluoromethylpyridine synthesis strategy is the use of fluoriaated aUphatic feedstocks for the ring-constmction sequence. Examples iaclude the manufacture of the herbicide dithiopyr, utilising ethyl 4,4,4-trifluoroacetoacetate [372-31-6] CF2COCH2COOC2H (436,437). 2,3-Dichloro-5-trifluoromethylpyridine [69045-84-7], a precursor to several crop-protection chemicals (see Table 15), can be prepared by conversion of l,l,l-trichloro-2,2,2-trifluoroethane [354-58-5], CF CCl, to 2,2-dichloro-3,3,3-trifluoropropionaldehyde [82107-24-2], CF2CCI2CHO, followed by cycUzation with acrylonitrile [107-13-1] (415). 

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). 

Halothane. Halothane or Fluothane, 2-bromo-2-chloro-l,l,l-trifluoroethane [151 -67-7] is a colorless Hquid with a pleasant odor. Its lower flammability limit, 4.8% in 70% N2O/30% O2, renders it essentially nonflammable. It has a vapor pressure of 32.5 kPa (244 mm Hg) at 20 °C and is stable to soda lime. However, it is photochemicaHy reactive. 

In the presence of catalysts, trichloroethylene is readily chlorinated to pentachloro- and hexachloroethane. Bromination yields l,2-dibromo-l,l,2-trichloroethane [13749-38-7]. The analogous iodine derivative has not been reported. Fluorination with hydrogen fluoride in the presence of antimony trifluoride produces 2-chloro-l,l,l-trifluoroethane [75-88-7] (8). Elemental fluorine gives a mixture of chlorofluoro derivatives of ethane, ethylene, and butane. 

Photochlorination of tetrachloroethylene, observed by Faraday, yields hexachloroethane [67-72-1]. Reaction with aluminum bromide at 100°C forms a mixture of bromotrichloroethane and dibromodichloroethane [75-81-0] (6). Reaction with bromine results in an equiUbrium mixture of tetrabromoethylene [79-28-7] and tetrachloroethylene. Tetrachloroethylene reacts with a mixture of hydrogen fluoride and chlorine at 225—400°C in the presence of zirconium fluoride catalyst to yield l,2,2-trichloro-l,l,2-trifluoroethane [76-13-1] (CFG 113) (7). 

Chlo r ofluo r oca rho ns. I,I,I-trichloro-2,2,2-trifluoroethane trichlorofluoromethane, dichlorodifluoromethane chlorodifluoro-methane I,2-dichloro-I,I,2,2-tetrafluoroethane chloropentafluoro-ethane... 

TRIFLUOROETHANE 83 C2H6S METHYL-SULFIDE -33.596 1.1704E-01 6.2933E-05 6.95... 

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