111.6 g of nonafluoro-n-butanesulfonyl fluoride (370 mmol) were added at room temperature to a solution of 45.6 g of racemic binaphthol (160 mmol) and 47.6 g of triethylamine (470 mmol; 65.5 ml) in 350 ml of dichloromethane. After a few minutes, the denser sulfonyl phase had disappeared, without the mixture warming appreciably. After stirring for 4 hours, the mixture was shaken once with 80 ml of aqueous sodium hydroxide solution (5% by weight) and once with 80 ml of water, and the organic phase was dried over sodium sulfate and concentrated on a rotary evaporator. The product crystallized out on cooling and was purified further by washing with a small amount of cold methanol and subsequent filtration with suction. This gave 123 g of binaphthol dinonaflate (90.0%) as colourless crystals having a melting point of 104.1° C.; HPLC purity>99% (RP-18; methanol/water 80:20; 254 nm)
