1-Iodo-4-(heptafluoroisopropoxy)octafluorobutane (CAS# 25080-17-5) is a perfluoroalkylating agent and useful building block. 1-Iodo-4-(heptafluoroisopropoxy)octafluorobutane can be polymerized and cured to give strong stable plastics useful for oxygen-transport membrane.