p-Toluenesulfonic acid → 1,3-Dithiane-2-carboxylic acid

Participants

Reaction Steps

9.20 g (100 mmol) of glyoxalic acid monohydrate, 11.1 ml (110 mmol) of 1,3-propanedithiol and 1.72 g (10.0 mmol) of para-toluenesulphonic acid were heated in 200 ml of toluene under reflux for 3 h. The reaction mixture was cooled to RT and extracted three times with 100 ml of saturated aqueous sodium bicarbonate solution. The combined aqueous phases were washed with 200 ml of diethyl ether, acidified with aqueous hydrochloric acid (6N) and extracted four times with 200 ml of ethyl acetate. The combined organic phases were dried over magnesium sulphate and filtered, and the solvent was removed under reduced pressure. The residue was used for the next step without further purification. Yield: 8.0 g (47% of theory)

Provenance & Evidence