Water → 2-[2-(Heptafluoropropoxy)-tetrafluoroethyl]-ethyl alcohol

C3F7OCF2CF2I (100 g, 0.24 mol) and benzoyl peroxide (3 g) were charged under nitrogen into a vessel. A series of three vacuum/nitrogen gas sequences was then executed at −50° C. and ethylene (18 g, 0.64 mol) was introduced. The vessel was heated for 24 h at 110° C. The autoclave was cooled to 0° C. and opened after degassing. Then the product was collected in a bottle. The product was distilled to provide C3F7OCF2CF2CH2CH2I (80 g, 80% yield): bp 56-60° C. at 25 mm Hg (3325 Pa). A mixture of C3F7OCF2CF2CH2CH2I, (300 g, 0.68 mol) and N-methyl-formamide (300 mL), was heated to 150° C. for 26 h. Then the reaction was cooled to 100° C., followed by the addition of water to separate the crude ester. Ethyl alcohol (77 mL) and p-toluene sulfonic acid (2.59 g) were added to the crude ester, and the reaction was stirred at 70° C. for 15 minutes. Then ethyl formate and ethyl alcohol were distilled out to give a crude product. The crude product was dissolved in ether, washed with aqueous sodium sulfite, water, and brine in turn, then dried over magnesium sulfate. The product was then distilled to provide C3F7OCF2CF2CH2CH2OH (B3, 199 g, 85% yield): bp 71˜73° C. at 40 mmHg (5320 Pa).