A clean, dry, 600 mL, stainless steel, Parr pressure reactor was charged with spray-dried potassium fluoride (10.0 grams, 0.17 mole), anhydrous diglyme (129 grams), and Adogen™ 464 phase transfer catalyst (2.2 grams). The reactor was sealed, cooled with a dry ice-acetone bath, evacuated, and charged with perfluoropropionyl fluoride (70.0 grams, 0.42 mole) and C3F7OCF(CF3)CF2OCF═CF2 (170 grams, 0.39 mole). The reactor was heated to 85° C., held for 16 hours with agitation, and cooled to room temperature. The resulting intermediate ketone-containing reaction mixture (0.39 mole based on starting vinyl ether) was used without further purification and was combined with an additional amount of anhydrous diglyme (1000 grams), potassium fluoride (35.7 grams, 0.62 mole), catalyst (28 grams, 56 percent solution in diglyme), and diethyl sulfate (121.2 grams, 0.79 mole) in a 3 L flask. With stirring, the flask was heated to 52° C. for 16 hours. At the end of this time, potassium hydroxide (52 grams, dissolved in 300 g water) was added, and the resulting mixture was heated to 65° C. and then distilled azeotropically using a Dean Stark trap, from which the resulting lower fluorochemical phase was separated during the distillation. The resulting product was distilled (b.p.=189-191° C.) to a purity of 92 percent. Product structure was confirmed by IR and GCMS.
