3-(Trifluoromethyl)-3,4,4-trifluoro-1-oxa-2-thiacyclobutane 2,2-dioxide773-15-9100 % similar 2-Hydroxytetrafluoroethanesulfonic acid β-sultone697-18-750 % similar Nonafluorobutanesulfonic acid anhydride36913-91-434 % similar Trifluoromethanesulfonic anhydride358-23-633 % similar Perfluoro(2-ethoxyethane)sulfonic acid113507-82-731 % similar Methyl trifluoromethanesulfonate333-27-730 % similar