Process for perhalocycloalkane purification

Abstract

A process is disclosed for recovering at least one perhalocycloalkane selected from the group consisting of octafluorocyclobutane, hexafluoro-bis(trifluoromethyl)cyclobutane (1,2 and 1,3; cis and trans), 1,2-dichloro-1,2,3,3,4,4-hexafluorocyclobutane (cis and trans), 1,1,2,2-tetrachloro-3,3,4,4-tetrafluorocyclobutane, 1-chloro-1,2,2,3,3,4-hexafluoro-4-(trifluoromethyl)-cyclobutane, heptafluoro(trifluoromethyl)cyclobutane and chloroheptafluoro-cyclobutane from a mixture comprising (a) the perhalocycloalkane, (b) olefinic impurity and optionally (c) saturated fluorine-containing impurity selected from the group consisting of hydrochlorofluorocarbons, hydrofluorocarbons and mixtures thereof. The process involves (1) contacting the mixture with chlorine under conditions suitable for chlorinating the olefinic impurity, thereby converting the olefinic impurity to a saturated impurity containing at least one chlorine substituent and reducing the hydrogen content of the saturated fluorine-containing impurity (if present), and (2) separating said at least one perhalocycloalkane from the products produced during the chlorination of (1). Also disclosed is a process for producing n-decafluorobutane. The process involves contacting a mixture comprising octafluorocyclobutane (i.e., C-318) and 1,1,1,2,3,4,4,4-octafluorobutene-2 (FC-1318my) with chlorine under conditions suitable for converting the FC-1318my to 2,3-dichloro-1,1,1,2,3,4,4,4-octa-fluorobutane (i.e., CFC-318mbb); separating the C-318 from the CFC-318mbb; and reacting the CFC-318mbb with HF.

Dependencies are inferred from the claim text.