in water K2S2O7 (contaminated with 40percent KHSO4) dild. in ammonia water (25percent/shakingfor 0.5 h/cooling with cold water); until evolution of heat stops; heating (3 min/water bath);; left cooling; filtration, washing (ammonia water); evapn.; addn. of concd. H2SO4; left for several hours (common temps.); filtration; drying on clay; recrystn. from water;;
in water byproducts: dimethylaniline; diln. in ice cold ammonia water (10percent NH3/) left warming up to common temps. under sepn. of (CH3)2NC6H5;; evapn. (removal of exceeding NH3 and (CH3)2NC6H5/water bath); addn. of concd. H2SO4; sepn. of HSO3NH2;;
