A new and convenient synthesis of trifluoromethyl trifluoromethanesulfonate (trifluoromethyl triflate, TFMT) has been devised. The addition of triflic anhydride to a catalytic amount of antimony pentafluoride at 25" C produces TFMT in 94% yield, utilizing a new and stronger Lewis acid catalyst produced in the reaction, F4SbOS02CF3. This reaction makes pure TFMT conveniently and economically available in large quantities. A mechanism is ...