67868-84-2

50-00-0

1073-72-9

67868-84-2

To a suspension of 4-(methylthio)phenol (50 g, 357 mmol), paraformaldehyde (72.3 g, 2407 mmol) and anhydrous magnesium chloride (50.9 g, 535 mmol) in acetonitrile (500 mL) was added triethylamine (186 mL, 1337 mmol). The reaction mixture was stirred at room temperature and then warmed to 60 °C and stirred continuously for 5 hours. Upon completion of the reaction, the mixture was cooled to 0 °C and 1N hydrochloric acid was slowly added until the two phases separated (~1.5 L). Methyl tert-butyl ether (MTBE, 700 mL) was then added and the organic layer was separated. The organic layer was washed with saturated brine, dried over anhydrous sodium sulfate, filtered and concentrated under reduced pressure. The crude product was purified by fast column chromatography on silica gel with the eluent being a 1:1 hexane/dichloromethane solvent mixture to afford 2-hydroxy-5-(methylthio)benzaldehyde (50.5 g, 300 mmol, 84% yield) as a semi-solid.