In 35 ml of n-hexane were suspended 6.07 g (0.03 mol) of diphenylsulfoxide and 6.06 g (0.036 mol) of diphenylmethane, and 7.56 g (0.036 mol) of trifluoroacetic anhydride was added thereto at 0° C. Then 4.5 g (0.03 mol) of trifluoromethanesulfonic acid was added dropwise thereto at 0 to 5° C., followed by gradually warming to room temperature and reacting for 4 hours with stirring. After completion of the reaction, 50 ml of water was poured into the reaction solution and the n-hexane layer was removed by fractionation. The aqueous layer was further washed with 50 ml of hexane three times and extracted with 60 ml of dichloromethane. The resulting dichloromethane layer was washed with 50 ml of water five times, followed by concentration under reduced pressure. 70 ml of ethyl acetate was poured into the resulting crude crystal, followed by dissolving by warming to 60° C., cooling to room temperature, the resulting crude crystal was filtered and dried under vacuum to obtain 11.3 g (Yield: 75%) of diphenyl-4-phenylmethylphenylsulfonium trifluoromethanesulfonate as a pale brown crystal.
