4-Methylbenzenethiol → 3-((4-Methylphenyl)thio)propionic acid

Participants

Reaction Steps

With caution 210 g (1.5 moles) of 4-methylthio-phenol and 120 g (3.0 moles) of sodium hydroxide in 200 ml of water was slowly added to 163 g (1.51 mole) of 3-chloropropionic acid. The mixture was heated to reflux for 20 hours. After reflux the unreacted 4-methylthiophenol was removed by distillation and the hot reaction mixture poured with stirring onto ice and concentrated hydrochloric acid. The slurry was filtered and collected on a buchner funnel. The wet mass was added to a solution of 300 ml of 1% sodium hydroxide solution and 300 ml of ethyl acetate. The resulting mixture was poured into a one liter separatory funnel, and after extraction with 1% sodium hydroxide, the aqueous layer was drawn off. The organic layer was extracted a second and third time with 1% sodium hydroxide. The extracts were added to a two liter separatory funnel, acidified with concentrated hydrochloric acid after the ethyl acetate was layered on. The organic extract was collected and dried over anhydrous Na2SO4, and two heaping teaspoons of activated charcoal were added to the yellow solution. Filtering removed insolubles and the resulting light yellow solution was reduced to a white sticky solid using a rotary evaporator at 65° C. and reduced pressure. Recrystallization from hot benzene yields white needles of 3-(4-methylthiophenoxy)-propionic acid with a melting point of 129°-131° C. (uncorrected).

Provenance & Evidence