Continuous process for the preparation of pentafluoroethyl iodide

Pentafluoroethyl iodide is a valuable synthon for introducing the pentafluoroethyl group into organic compounds which, for example, have herbicidal action. However, pentafluoroethyl iodide has achieved greatest significance as a telogen in socalled telomerization with tetrafluoroethylene and/or hexafluoropropene. The perfluoroalkyl iodides which form in the process are important starting materials for numerous syntheses, which give active ingredients having strongly marked hydrophobic and oleophobic properties. Continuous process for the preparation of pentafluoroethyl iodide from iodine, iodine pentafluoride and tetrafluoroethylene, which comprises dissolving the iodine in iodine pentafluoride and continuously feeding the resulting solution to a vertical bubble column (), which is filled with iodine pentafluoride and at its lower end has a feed line for tetrafluoroethylene, where the reaction zone is maintained at from 85 to 95° C., preferably 90° C., and the pentafluoroethyl iodide formed escapes in gaseous form at the top of the reactor (), is liquefied in a downstream cooled condenser and is drawn off into storage vessels.