Inside the glove box, a 100 mL round-bottom flask equipped with a reflux condenser, stirring bar, and septum was charged with 4′-bromo-biphenyl-4-sulfonyl chloride (6.63 g, 20 mmol), octafluorobutane-1,4-disulfonamide (3.60 g, 10 mmol), and acetonitrile (40 mL). Triethylamine (6 mL, 40 mmol) was added slowly by syringe. The solution was heated to a reflux overnight. The solution was cooled to room temperature, poured into an aqueous solution (150 mL) of 20% sodium hydroxide, and chilled in an ice bath to induce precipitation. The precipitate was collected by vacuum filtration dried under vacuum to give 9.86 g (99% yield). The solids were recrystallized by dissolving in water at a reflux, treating with decolorizing carbon, filtering the solution, and concentrating the solution at a reflux to 200 mL to induce crystallization. The white crystals were collected by vacuum filtration, washed with water, and dried overnight in a vacuum oven at 100° C. followed by 170° C. under a nitrogen purge to give 8.80 g (89% yield) of N,N′-bis(4′-bromo-biphenyl-4-sulfonyl)-octafluorobutane-1,4-disulfonamide, disodium salt, shown below. 1H NMR (DMSO-d6): 7.67 (bm, 4H), 7.78 (d, J=8 Hz, 2H), 7.84 (d, J=8 Hz, 2H). 19F NMR (DMSO-d6): -120.36 (m, —CF2—CF2—), −113.06 (m, 2 —CF2-SO2—).
