Water → 4-(Benzyloxy)benzene-1-sulfonyl chloride

To a suspension of 22.4 g (146 mmol) of sulfur trioxide/DMF complex in 60 mL of anhydrous 1,2-dichloroethane at room temperature, was added a solution of 30 g (162 mmol) of benzylphenyl ether in 30 mL of anhydrous 1,2-dichloroethane. The resulting mixture was warmed to reflux and maintained there for 1 hour, cooled to room temperature and 10.8 mL (146 mmol) of thionyl chloride added. The reaction was then warmed to 75 C for 1 hour, cooled in an ice bath, 50 mL of water slowly added, then ethyl acetate. The layers were separated, washed with saturated sodium bicarbonate, brine, dried with magnesium sulfate, filtered and stripped. The resulting solids were triturated with hexane to afford 24.5 g of pure 4-(Benzyloxy)benzenesulfonyl chloride.