Process for the manufacture fluorocarbons
View Patent ↗Halocarbons of the structure CF 3 CF 2 CH 2 X, wherein X is either F or Cl or mixtures thereof prepared by: contacting at least one 2-fluorochloropropane with hydrogen fluoride in a first fluorination step in the gas phase or liquid phase under substantially anhydrous conditions, in the absence of added catalyst to partially fluorinate said 2-fluorochloropropane; contacting said partially fluorinated 2-fluorochloropropane with at least the stoichiometric molar equivalent of hydrogen fluoride under substantially anhydrous conditions, in the presence of at least one fluorination catalyst in a second fluorination step; removing said reaction products from contact with said catalyst, and isolating a substantial yield of at least 1,1,1,2,2,3-hexafluoropropane or 1,1,1,2,2, penta-3-chloropropane, or mixtures thereof, respectively.
1. An azeotropic or near-azeotropic composition comprising from about 11.4 mole percent to about 38.8 mole percent 1,1,1,2,2-pentafluoro-3-chloropropane, and from about 61.2 mole percent to about 88.6 mole percent hydrogen fluoride.
2. The azeotropic composition of claim 1 , comprising from about 17.3 mole percent to about 34.9 mole percent 1,1,1,2,2-pentafluoro-3-chloropropane and from about 65.1 to about 82.7 mole percent hydrogen fluoride.
3. The near-azeotropic composition of claim 2 comprising from about 11.4 mole percent to about 38.8 mole percent 1,1,1,2,2-pentafluoro-3-chloropropane and from 61.2 to 88.6 mole percent hydrogen fluoride, wherein the vapor pressure is from about 4.2 psia to about 245.6 at a temperature of from about −20° C. to about 120° C.
4. A process for the separation of 1,1,1,2,2-pentafluoro-3-chloropropane from a mixture comprising an azeotropic or near-azeotropic composition of 1,1,1,2,2-pentafluoro-3-chloropropane and hydrogen fluoride, said process comprising:
a) subjecting said mixture to a first distillation step in which a composition enriched in either (i) hydrogen fluoride or (ii) 1,1,1,2,2-pentafluoro-3-chloropropane is removed as a first distillate composition with a first bottoms composition being enriched in the other of said components (i) or (ii); and
b) subjecting said first distillate composition to a second distillation step conducted at a different pressure than the first distillation step in which the component enriched as first bottoms composition in (a) is removed as an azetotrope in a second distillate composition with a second bottoms composition enriched in the same component which was enriched in the first distillate composition.
5. The process of claim 4 wherein said second distillation step is carried out at a pressure greater than the pressure of the first distillation step.
6. The azeotropic composition of claim 2 , having a vapor pressure of from about 15 psia to about 480 psia, at a temperature of from about 8.2 ° C. to about 127.1° C.
7. An azeotropic or near-azeotropic composition consisting essentially of from about 11.4 mole percent to about 38.8 mole percent 1,1,1,2,2-pentafluoro-3-chloropropane, and from about 61.2 mole percent to about 88.6 mole percent hydrogen fluoride.
8. The azeotropic composition of claim 7 , consisting essentially of from about 17.3 mole percent to about 34.9 mole percent 1,1,1,2,2-pentafluoro-3-chloropropane and from about 65.1 to about 82.7 mole percent hydrogen fluoride.
9. The near-azeotropic composition of claim 7 consisting essentially of from about 11.4 mole percent to about 38.8 mole percent 1,1,1,2,2-pentafluoro-3-chloropropane and from 61.2 to 88.6 mole percent hydrogen fluoride, wherein the vapor pressure is from about 4.2 psia to about 245.6 at a temperature of from about −20° C. to about 120° C.
10. The azeotropic composition of claim 7 , having a vapor pressure of from about 15 psia to about 480 psia, at a temperature of from about 8.2° C. to about 127.1° C.