Methanol → 4-Methanesulfonylbutan-1-ol

4-(Methylthio)butan-1-ol (721 mg, 6.0 mmol) was dissolved in methanol (15 mL) and cooled to 0° C. in an ice bath. 2KHSO5.KHSO4.K2SO4 (4057 mg, 6.60 mmol), dissolved in water (15 mL), was added dropwise over a 10 minute period. Upon completion of addition, the reaction mixture was removed from the ice bath and warmed to room temperature and stirred for one hour. The reaction mixture was diluted with water (15 mL) and extracted with ethyl acetate (50 mL). The aqueous layer was concentrated to dryness, and the residue was diluted with dichloromethane, stirred 30 minutes and filtered. The filtrate was concentrated to give the title compound as a clear oil (825 mg, 90%).