Allyl bromide → 4,4,5,5,6,6,7,7,7-Nonafluoro-1-heptene

A mixture of perfluorobutyl iodide (103.8 g, 0.3 mol), copper powder (50 g, 0.79 mol) and dimethyl sulfoxide (150 mL) was stirred at 110°-120° C. for 2 hr, then cooled to room temperature. Allyl bromide (36.3 g, 0.3 mol) was added dropwise and then the mixture was stirred at room temperature for 2 hr and at 50° C. for 1 hr. The reaction mixture was distilled in vacuo and the crude product was collected in a cold trap (-78° C.). Redistillation produced 55.2 g (70% yield) of the desired 4,4,5,5,6,6,7,7,7-nonafluoro-1-heptene, formula above, having a boiling point of 79°-80° C.