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Fluorocarbon synthesis: halogen exchange fluorination with alkali metal polyhydrogen fluorides
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B5 The syntheses of anhydrous TaF, and NbF5 and their use in the synthesis of HCFC-123 (CHCl,CF,) Mario J. Nappa L&L Pant Chemicals
Experimental
Station,
Wilmington,
DE 19880 (USA)
Lewis acids TaF, and NbFF, are reported to catalyze the conversion of chloroethanes or chloroethylenes in the presence of HF to make HCFC-123, an HCFC alternative to CFC-11 (CFCla) [A. E. Feiring, US Put. 4 258225 (1981); W. H. Gumprecht, W. G. Schindel and V. Felix, US Pat. 4 967024 (1990) 1. However, both TaF, and NbFF,are expensive for use on a commercial scale. The synthesis of anhydrous TaF, and NbF, from their corresponding metal oxides in a single step in situ and their use as catalysts to make HCFC-123 will be discussed.
B6 Fluorocarbon synthesis: halogen exchange alkali metal polyhydrogen fluorides Richard E. Fernandez I)u Punt Company, Experimental
Station, Wilmington,
fluorination with
DE 19880-0262 (USA)
Joseph S. Thrasher*, Liang Hu, and H. P. Sampath Kumar Department
of Chemistry,
The University
of Alabama,
Tuscaloosa, AL 35487 @JsA)
A variety of fluorocarbons of current interest can be efficiently prepared via halogen exchange fluorination with alkali metal polyhydrogen fluorides, MF-nHF, where M =K, Rb, Cs or mixtures thereof and n= 0.5 to 3. [R. E. Fernandez, et al., US Pats. 4 990 701, 4 990 702 and 5 045 634 (1991)I. The alkali metal polyhydrogen fluorides can be thought of as ‘participatory solvents’ for traditional alkali metal fluoride halogen exchange reactions, since the amount of free fluoride can be readily controlled by the addition/ removal of HF as well as by varying the temperature. Thus, by controlling “n”, this methodology can be used not only for substitution reactions, but HF addition and HF elimination reactions as well. Once the desired halogen exchange/addition/elimination has taken place, the fluoride source can be easily regenerated via the addition of HF and removal of HCl. The chemical and physical properties of these systems as well as their applicability towards fluorocarbon synthesis will be presented. *Visiting Research 19880 (USA).
Scientist, L?u Pony Company,
Experimentul
Station, Wilmington,
DE
B5 The syntheses of anhydrous TaF, and NbF5 and their use in the synthesis of HCFC-123 (CHCl,CF,) Mario J. Nappa L&L Pant Chemicals
Experimental
Station,
Wilmington,
DE 19880 (USA)
Lewis acids TaF, and NbFF, are reported to catalyze the conversion of chloroethanes or chloroethylenes in the presence of HF to make HCFC-123, an HCFC alternative to CFC-11 (CFCla) [A. E. Feiring, US Put. 4 258225 (1981); W. H. Gumprecht, W. G. Schindel and V. Felix, US Pat. 4 967024 (1990) 1. However, both TaF, and NbFF,are expensive for use on a commercial scale. The synthesis of anhydrous TaF, and NbF, from their corresponding metal oxides in a single step in situ and their use as catalysts to make HCFC-123 will be discussed.
B6 Fluorocarbon synthesis: halogen exchange alkali metal polyhydrogen fluorides Richard E. Fernandez I)u Punt Company, Experimental
Station, Wilmington,
fluorination with
DE 19880-0262 (USA)
Joseph S. Thrasher*, Liang Hu, and H. P. Sampath Kumar Department
of Chemistry,
The University
of Alabama,
Tuscaloosa, AL 35487 @JsA)
A variety of fluorocarbons of current interest can be efficiently prepared via halogen exchange fluorination with alkali metal polyhydrogen fluorides, MF-nHF, where M =K, Rb, Cs or mixtures thereof and n= 0.5 to 3. [R. E. Fernandez, et al., US Pats. 4 990 701, 4 990 702 and 5 045 634 (1991)I. The alkali metal polyhydrogen fluorides can be thought of as ‘participatory solvents’ for traditional alkali metal fluoride halogen exchange reactions, since the amount of free fluoride can be readily controlled by the addition/ removal of HF as well as by varying the temperature. Thus, by controlling “n”, this methodology can be used not only for substitution reactions, but HF addition and HF elimination reactions as well. Once the desired halogen exchange/addition/elimination has taken place, the fluoride source can be easily regenerated via the addition of HF and removal of HCl. The chemical and physical properties of these systems as well as their applicability towards fluorocarbon synthesis will be presented. *Visiting Research 19880 (USA).
Scientist, L?u Pony Company,
Experimentul
Station, Wilmington,
DE