Production of 1,2-dihydro and 2,2-dihydro hexafluoropropanes and

Abstract

CF.sub.3 CHFCHF.sub.2 production is disclosed which involves reacting CF.sub.3 CF.dbd.CHF with HF at an elevated temperature over a catalyst selected from the group consisting of aluminum fluoride, fluorided alumina, metals supported on aluminum fluoride, metals supported on fluorided alumina and catalysts comprising trivalent chromium. Also disclosed is enrichment of CF.sub.3 CF.dbd.CHF from a starting mixture containing CF.sub.3 CF.dbd.CHF and CF.sub.3 CH.dbd.CF.sub.2 which involves reacting said starting mixture with HF at an elevated temperature over a catalyst consisting essentially carbon, a catalyst consisting essentially of metal halides supported on carbon, a catalyst consisting essentially of Cr.sub.2 O.sub.3, or mixtures thereof (provided that when Cr.sub.2 O.sub.3 is present the temperature is about 250.degree. C. or less) to produce a product mixture containing CF.sub.3 CH.sub.2 CF.sub.3 and unreacted CF.sub.3 CF.dbd.CHF wherein the mole ratio of CF.sub.3 CF.dbd.CHF to CF.sub.3 CH.dbd.CF.sub.2 is greater than the ratio thereof in the starting mixture. Compositions are disclosed which consist essentially of hydrogen fluoride in combination with an efective amount of a compound selected from the group consisting of CF.sub.3 CHFCHF.sub.2 and CF.sub.3 CH.sub.2 CF.sub.3 to form an azeotrope or azeotrope-like composition with hydrogen fluoride. Included are compositions containing from about 31 to 60 mole percent CF.sub.3 CHFCHF.sub.2 and compositions containing from about 41 to 63 mole percent CF.sub.3 CH.sub.2 CF.sub.3.