Hoechst Aktiengesellschaft

Karl Rettenbeck

Thomas Schottle

Ingolf Mielke

Herbert Weber

Reinhold Freudenreich

Werner Dostler

A process for the preparation of hexafluoropropene by thermal cleavage of chlorotetrafluoroethane and/or chlorohexafluoropropane or a mixture of chlorotetrafluoroethane and perfluorocyclobutane at 600.degree. to 1,000.degree. C. and under a pressure of 1 to 1,000 kPa is described. The thermal cleavage is carried out in the presence of at least 0.05 mole of tetrafluoroethylene per mole of chlorotetrafluoroethane and/or chlorohexafluoropropane or mixture of chlorotetrafluoroethane and perfluorocyclobutane employed. By means of this process hexafluoropropene is obtained for a small extra expenditure on apparatus at a good selectivity and in an improved space-time yield.

Process for the preparation of hexafluoropropene

A process for the preparation of mixtures of chlorotetrafluoroethane and octafluorocyclobutane from the gas stream from the pyrolysis of chlorodifluoromethane at temperatures above 600.degree. C. is described in which the principal constituents tetrafluoroethylene and hexafluoropropylene as well as hydrogen chloride are removed in advance. The mixtures are obtained by withdrawal as a side fraction during the rectifying distillation of the residue remaining, a clean separation of the perfluorocyclobutenes advantageously taking place. The mixtures are used for obtaining hexafluoropropylene by pyrolysis.

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Burgkirchen, Germany

Karl Rettenbeck