Dimethyl Carbonate → Methyl Pentafluoroethanesulfonate

5.74 g (15.0 mmol) of pentafluoroethanesulfonic anhydride and 0.31 g (1.55 mmol) of pentafluoroethanesulfonic acid are initially introduced in a 10 ml round-necked flask. 1.35 g (15.0 mmol) of dimethyl carbonate are added at room temperature with constant stirring and reflux cooling. The solution is stirred for one hour at a temperature of 60° C. and subsequently for a further 3 hours at 110° C. After distillation, 5.41 g of methyl pentafluoroethanesulfonate are isolated (boiling range: 114–115° C., yield: 84.1%).