Process for separating mixtures of crude, water-containing amines originating from the amine synthesis

摘要

Separation of mixture of amine(s), water, low-boiling fraction and optionally high-boiling fraction includes optional distillative separation of low and high-boiling fractions, extraction of mixture with aqueous sodium hydroxide solution; and distillation of resultant aqueous-organic phase to recover anhydrous amine(s) from sump or side in separation part of column and amine/water azeotrope. <??>Separation of a mixture containing amine(s) (I), water, low-boiling fraction (II) and optionally high-boiling fraction (III) comprises: <??>(i) optional distillative separation of a first low-boiling fraction; <??>(ii) optional distillative separation of a first high-boiling fraction; <??>(iii) extraction of the mixture with aqueous sodium hydroxide (NaOH) solution, giving a first aqueous phase containing NaOH solution and a second aqueous-organic phase (IV) containing amines, other low-boiling fractions and optionally other high-boiling fractions; and <??>(iv) distillation of the aqueous-organic phase to recover anhydrous amines as sump discharge or side discharge in the separation part of the column, an amine/water azeotrope, which is recycled to (iii), as side discharge in the concentration part and further low-boiling fraction as top discharge.