in vacuum the residue is dissolved in 100 ml of ether and the ether solution is stirred for 30 minutes with 100 ml of 0 5 n hydrochloric acid at 0 u00b0 5 u00b0 after washing twice with 50 ml of water drying over sodium sulfate and evaporating 2 3 g of a thick oil are obtained from the organic phase which crystallizes partly after two days the crystals are recrystallized from benzol cyclohexane 0 5 g of dl u03b1 methylthio thioxomethoxy benzeneacetic acid are obtained in the form of white crystals m p 109 u00b0 110 u00b0 b 4 56 g 30 mm of dl mandelic acid are dissolved in 100 ml of carbon disulfide and 3 37 g 60 mm of pulverized potassium hydroxide are added all at once absolute dimethylsulfoxide is then added with stirring until a clear solution is obtained the whole is stirred for 1 hour and then 4 26 g 30 mm of methyl iodide are added after 4 hours the carbon disulfide is removed in vacuum and the oily residue is dissolved in 200 ml of water the aqueous solution is extracted three times with 50 ml of ether after cooling the aqueous phase.