At first, an aqueous solution was prepared by dissolving 37.5 g of sodium sulfite in 150 g of water. Then, a metal pressure-proof reactor was charged with this aqueous solution. After that, the atmosphere of the reactor was removed to obtain a reduced pressure. 10.7 g of trifluoromethanesulfonic fluoride was added to the reactor, stirring at 5° C. for 4 hr. The resulting reaction liquid was neutralized with sodium 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, thereby obtaining 9.7 g of sodium trifluoromethanesulfinate (yield: 88%).
