At first, an aqueous solution was prepared by dissolving 125 g of potassium sulfite in 290 g of water. Then, a metal pressure-proof reactor was charged with this aqueous solution. Then, the atmosphere of the reactor was removed to obtain a reduced pressure. After that, 30.7 g of trifluoromethanesulfonic fluoride was added to the reactor, stirring from 0° C. to room temperature for 12 hr. The resulting reaction liquid was neutralized with potassium carbonate, followed by water removal. Then, methanol was added to the remaining solid matter to extract the target product. The resulting methanol solution was concentrated to dryness, obtaining 32.6 g of potassium trifluoromethanesulfonate (94%).
