Patent ID: 6506948
Filing Date: 2003-01-14
Classification: C07C

Abstract:
In a process for the production of dinitrotoluene which comprises contacting toluene with a mixture of nitric and sulfuric acid under conditions for effecting dinitration and generating three acidic aqueous streams contaminated with residual levels of mononitrotoluene, dinitrotoluene and organic by-products, said acidic aqueous streams formed in the purification of the dinitrotoluene reaction product and concentration of spent sulfuric acid, one wastewater stream generated from spent sulfuric acid and referred to as weak acid wastewater; one from the washing of the dinitrotoluene reaction product and referred to as acid wash water stream, and one resulting from alkaline washing of the dinitrotoluene reaction product and referred to as alkaline wash water stream; the improvement which comprises the steps:(a) initially extracting mononitrotoluene, dinitrotoluene and organic by-products from at least one stream selected from the group consisting of the weak acid wastewater stream and acid wash water stream by contacting the stream with toluene and thereby generating an organic phase and an aqueous phase; (b) separating the thus formed organic phase from the aqueous phase; (c) extracting mononitrotoluene, dinitrotoluene and organic by-products from the alkaline wash water stream by contacting said stream with the organic phase generated in step (a) and thereby generating a toluene/dinitrotoluene organic layer and an extracted alkaline wash water fraction; and, (d) separating the toluene/dinitrotoluene organic layer from the extracted alkaline wash water fraction.