with a mechanical stirrer and thermometer was placed 401 5 g of commercial 2 acetylthiophene and 400 ml of tap water the stirrer was started mixing the immiscible liquids together vigorously at an internal temperature of 15 u00b0 20 u00b0 c there was added by powder funnel 27 75 g of 1 3 dibromo 5 5 dimethylhydantoin into the stirred mixture there was no exotherm the mixture was a slurry with the pinkish solid still insoluble and dispersed into both phases the reactor was closed and with continued vigorous stirring the temperature was raised to 20 u00b0 25 u00b0 c over 1 hour the reaction was monitored closely for a possible exotherm to ensure that the temperature did not exceed 40 u00b0 c the reactor contents were stirred at between 20 u00b0 and 27 u00b0 c for 5 hours by this time a test for oxidant using moist acidic starch iodide test paper was negative and the solid phase had completely dissolved to the two phase mixture was added a solution of 3 9 g of sodium thiosulfate dissolved in 83 ml of water the deep red colour went to an orange brown upon stirring for ten to fifteen minutes at room temperature into the two phase mixture was added 100 ml of methylene chloride and stirring continued for 15 minutes then the layers were allowed to separate the lower layer was cut the aqueous upper layer.