Process for manufacture of high purity 1, 1-dichlorotetrafluoroe

Details Process for manufacture of high purity 1, 1-dichlorotetrafluoroe Process for manufacture of high purity 1, 1-dichlorotetrafluoroe

1995-05-08

1996-08-13

Siegel, Alan

Organic compounds -- part of the class 532-570 series

Organic compounds

Halogen containing

570165, 570167, 570169, 570176, C07C 1908, C07C 1708

Patent

active

055457703

ABSTRACT:
A process is disclosed for producing a product comprising CCl.sub.2 FCF.sub.3 substantially free of CClF.sub.2 CClF.sub.2. The process includes (i) contacting a mixture of perhalogenated hydrocarbons which is essentially free of CClF.sub.2 CClF.sub.2 and comprises from 20 to 80 mole percent CCl.sub.3 CF.sub.3 and from 5 to 80 mole percent total of at least one compound selected from the group consisting of CCl.sub.2 .dbd.CCl.sub.2, CCl.sub.3 CCl.sub.2 F, CCl.sub.2 FCCl.sub.2 F and CClF.sub.2 CCl.sub.3 with HF and optionally Cl.sub.2 (provided that when the mixture comprises CCl.sub.2 .dbd.CCl.sub.2, Cl.sub.2 is supplied in a mole ratio of Cl.sub.2 to CCl.sub.2 .dbd.CCl.sub.2 of at least 1:2) over a fluorination catalyst at an elevated temperature no higher than 375.degree. C., to provide a product mixture comprising CCl.sub.2 FCClF.sub.2 and C.sub.2 Cl.sub.2 F.sub.4 wherein the ratio of CClF.sub.2 CClF.sub.2 to CCl.sub.2 FCF.sub.3 is less than about 1:50; (ii) recovering said C.sub.2 Cl.sub.2 F.sub.4 from the product mixture; (iii) isomerizing CCl.sub.2 FCClF.sub.2 from the product mixture to CCl.sub.3 CF.sub.3 in the presence of an isomerization catalyst; and (iv) recycling the CCl.sub.3 CF.sub.3 produced by the isomerization of step (iii) to step (i). The process may be used to produce high purity CH.sub.2 FCF.sub.3 when combined with the hydrodehalogenation of the high purity CCl.sub.2 FCF.sub.3 from step (ii) in the presence of HF.

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