Fluorinated chromia 1,1,1,2-tetrafluoroethane

Fundamental Properties of Fluorinated Chromia 198 Attempts to Describe Active Sites on Fluorinated Chromia 199 Synthesis of 1,1,1,2-Tetrafluoroethane Over Fluorinated Chromia 200 Oxidation States of Chromium 200 Doped Chromia Catalysts 201... 

The drop-in replacement selected for the most widely used CFC refrigerant, CCljFj, was 1,1,1,2-tetrafluoroethane, CHjFCFj (Figure 7.2). One of the routes to this compound used the existing technology for the fluorinated chromia-catalyzed route to CCljFCFj followed by a hydrodechlorination step the other used a new zinc-doped chromia catalyst precursor in a two-step process to convert CHQ=CCl2 to CH2FCF3 directly [16]. The doped chromia developed is described later in this chapter. 

Although antimony pentafluonde can fluorinate l,l,2-tnchloro-l,2,2-trifluo-roethane to chloropentafluoroethane, this route is not used industnally because antimony pentafluonde and hydrogen fluoride are too corrosive. Both dichloro-tetrafluoroethane and chloropentafluoroethane are produced by vapor-phase fluor-ination of tetrachloroethene with proprietary chromia catalysts at 300 to 500 °C (equation 1). 

Moore and Massey [61] detailed a reaction in which 1,1,2,2-tetrafluoroethane was isomerized to 1,1,1,2-tetrafluoroethane over chromia catalyst at 400°C, indicating that fluorine shifts may be catalyzed. The same authors also indicated that AIF3 and NaF may also be used as catalyst. Similar work for TFE has not been reported, though it stands to reason that such a shift would be beneficial to the formation of HFP (See Scheme 5.7). 

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