Patent ID: 6329559
Filing Date: 2001-12-11
Classification: C07C

Abstract:
A process for the manufacture of CF.sub.3 CF.dbd.CF.sub.2, and optionally at least one compound selected from CF.sub.3 CH.sub.2 CF.sub.3 and CF.sub.3 CHFCHF.sub.2, comprising:(a) contacting a reactor feed comprising precursor stream of at least one compound selected from halogenated propanes of the formula CX.sub.3 CH.sub.2 CH.sub.y X.sub.(3-y) and halogenated propenes of the formula CX.sub.3 CH.dbd.CH.sub.y X.sub.(2-y), where each X is independently selected from Cl and F and y is 0, 1 or 2, provided that the average fluorine content of said precursor stream is no more than 5 fluorine substituents per molecule, with HF and Cl.sub.2 in a chlorofluorination reaction zone containing a fluorination catalyst and operating at a temperature between about 150.degree. C. and 400.degree. C. to produce a reaction zone effluent comprising HF, HCl and a mixture of reaction products of said precursor stream which contains at least one compound of the formula C.sub.3 Cl.sub.2 F.sub.6 including CClF.sub.2 CClFCF.sub.3 and at least one compound of the formula C.sub.3 HClF.sub.6 including CHF.sub.2 CClFCF.sub.3 and has an average fluorine content which is at least one fluorine substituent per molecule more than the average fluorine content of the precursor stream;(b) distilling the reaction zone effluent of (a) to produce (i) a low-boiling component comprising HCl and when they are present in said reaction zone effluent, C.sub.3 F.sub.8, C.sub.3 ClF.sub.7 and C.sub.3 HF.sub.7, (ii) a hydrogenation feed component comprising at least one compound of the formula C.sub.3 Cl.sub.2 F.sub.6 including CClF.sub.2 CClFCF.sub.3 and at least one compound of the formula C.sub.3 HClF.sub.6 including CHF.sub.2 CClFCF.sub.3, and (iii) an underfluorinated component comprising halogenated propanes containing at least one chlorine substituent and from one to five fluorine substituents;(c) reacting the CClF.sub.2 CClFCF.sub.3 and CHF.sub.2 CClFCF.sub.3 of hydrogenation feed component (ii) with hydrogen to produce a mixture comprising CF.sub.3 CF.dbd.CF.sub.2 and CF.sub.3 CHFCHF.sub.2 ;(d) recovering the CF.sub.3 CF.dbd.CF.sub.2 from the product mixture of (c); and(e) returning the underfluorinated component (iii) to the chlorofluorination reaction zone.