METHOD FOR WASHING DINITROTOLUENE

摘要

The invention relates to a method for washing a raw mixture that is produced during the nitration of toluene following separation of the nitrating acid, and that contains dinitrotoluene, nitric acid, nitrogen oxides and sulphuric acid. Said method comprises two washing steps (WS-1iI) and (WS-II) in which i) in a first washing step (WS-1i), the raw mixture is extracted in a wash comprising at least one extraction stage, using a wash acid I that contains nitric acid, nitrogen oxides and sulphuric acid, the wash acid discharged from the first extraction stage (WS-1-1) of the first washing step (WS-1) having a total acid content of 20 to 40 wt.%, and a prewashed raw mixture being obtained, and ii) in a second washing step (WS-II), the prewashed raw mixture containing dinitrotoluene is extracted in a wash comprising at least one extraction stage, using a wash acid II, the wash acid discharged from the first extraction stage (WS-II-1) of the second washing step (WS-II) having a pH value of less than or equal to 4, and a mixture that contains dinitrotoluene and is substantially devoid of nitric acid, sulphuric acid and nitrogen oxides being obtained.