Water → 1-Methanesulfonyloxy-6,6,7,7,7-pentafluoroheptane

Triethylamine (25.83 ml, 185.3 mmol) and methanesulfonyl chloride (6.9 ml, 88.9 mmol) were added dropwise to a solution of 6,6,7,7,7-pentafluoroheptan-1-ol (14.1 g, 74.1 mmol) in dichloromethane (350 ml) at 0° C., followed by stirring for 1 hour. After the reaction was completed, water was added to the reaction mixture, which was then extracted twice with dichloromethane. The combined organic layers were washed with water and saturated aqueous sodium chloride, and then dried over anhydrous magnesium sulfate. After distilling off the solvent, the residue was purified by silica gel column chromatography (eluent: ethyl acetate/hexane=1/10) to give 1-methanesulfonyloxy-6,6,7,7,7-pentafluoroheptane (17.3 g, Yield 82%).