Abstract: Toluenediamine is produced and separated from by-products of the reaction by: a) hydrogenating dinitrotoluene in the presence of a catalyst, b) separating the catalyst, water and optionally solvent from the hydrogenation reaction mixture to give crude toluenediamine, and c) separating by distillation the crude toluenediamine in a separating wall column into at least four product streams P1, P2, P3 and P4. The product stream P1 is a stream containing low boilers. The product stream P2 is a stream containing o-toluenediamine. The product stream P3 is a stream containing m-toluenediamine. The product stream P4 is a stream containing high boilers and m-toluenediamine.

Abstract: Toluenediamine is produced and separated from by-products of the reaction by: a) hydrogenating dinitrotoluene in the presence of a catalyst, b) separating the catalyst, water and optionally solvent from the hydrogenation reaction mixture to give crude toluenediamine, and c) separating by distillation the crude toluenediamine in a separating wall column into at least four product streams P1, P2, P3 and P4. The product stream P1 is a stream containing low boilers. The product stream P2 is a stream containing o-toluenediamine. The product stream P3 is a stream containing m-toluenediamine. The product stream P4 is a stream containing high boilers and m-toluenediamine.

Abstract: Amine mixtures generated during the production of diaminotoluene by hydrogenating dinitrated aromatic compounds are treated to separate high boiling materials from the desired amine products. In this process, any water of reaction and any solvent are first removed from the diaminotoluene isomer mixture (TDA mixture). The low-boiling TDA isomers are then separated using a TDA isomer distillation column. In the process of the present invention, the bottom phase remaining after the initial distillation contains a mixture of m-TDA and high-boiling materials. This bottom phase is separated and concentrated until the high-boiling material content is from approximately 25 to 60 wt. %. This concentrated bottom phase is then mixed with o-TDA in a ratio of 1:1 to 1:5 and a m-/o-TDA mixture is removed by distillation. The m-/o-TDA mixture thus recovered is then returned to the TDA isomer distillation column.