Example 4
Synthesis of 4-(3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl)-2-(2,2,2-trifluoroethoxy)-1,3-dioxolane. Tris(2,2,2-trifluoroethyl)orthoformate (1.4 eq., 48 mmol, 15 g, SynQuest Laboratories) and 5,5,6,6,7,7,8,8,9,9,10,10,10-tridecafluorodecane-1,2-diol (14 g, 34 mmol, 1 eq., Shanghai Chemhere Co., Ltd.) was dissolved in 240 mL of anhydrous cyclohexane (Aldrich) in a round bottom flask. The resulting solution was slightly cloudy and trifluorotoluene (Aldrich) was added dropwise until the solution was clear (5 mL). A catalytic amount of p-toluenesulfonic acid (Aldrich) was added to the flask along with a Teflon coated magnetic stirbar. The flask was fitted with a Dean-Stark distillation head. The reaction was slowly heated to reflux and the trifluoroethanol was removed by azeotropic distillation at a boiling point of 65° C. After 1 hour, the reaction was complete and the flask was cooled to room temperature. The reaction mixture was concentrated at reduced pressure on a rotary evaporator. The residual mixture was purified by fractional distillation under reduced pressure (b.p.=85-104° C. at 0.05 mmHg), providing the title compound in 44% isolated yield. The product was verified by characteristic peaks in the 1H NMR and by molecular ion in ESI/TOF mass spectroscopy (M+1, 519.1, 520.1 m/z).