perfluoropiperidino- and perfluoropropoxy-subs perfluoroalkyl iodides were synthesized directly by the reaction of the corresponding perfluoroacylfluorides with lithium iodide in high yield. Under controlled reaction conditions, it was possible to synthesize either iodo-perfluoroacyl fluorides or perfluoroalkylidene diiodides by the reaction of perfluoro(alkanedioyl) difluorides with lithium iodide. Perfluoro(