Perfluorobutane-1,4-disulfonic acid potassium salt (2.92 g) in 100 ml water was added to a solution of tris(4-t-butylphenyl)sulfonium hydroxide (7.75 g) in 150 ml of acetone. Chloroform (150 ml) was added and stirred for 5 hours. The chloroform layer was washed several times with water, dried over anhydrous sodium sulfate, filtered, and the filtrate evaporated to an oil stage. Ether was added to the oil and the mixture was stirred vigorously. A white precipitate formed. The mixture was filtered and the recovered precipitate was dried under vacuum, resulting in a white powder; mp 190° C.
