Patent ID: 8455691
Filing Date: 2013-06-04
Classification: C07C

Abstract:
1. A process for the purification of an aromatic amine prepared by reduction of an aromatic nitro compound in which a product mixture is obtained by reducing the aromatic nitro compound comprising subjecting the product mixture to steps I. through VI: I. separating off the water of reaction formed during the reduction by phase separation, wherein, in the crude amine obtained in this way, a residual content of water corresponding to the solubility of water in the crude amine is established, which depends on the pressure and temperature and the precise composition of the crude amine and which is between 2 and 10 per cent by weight, based on the weight of the crude amine, II. mixing the product mixture from I with an aqueous solution of an alkali metal hydroxide, III. feeding of the mixture from step II into a distillation column comprising at least an upper rectifying part (VT IV. removing at least a portion of any bottom product in the region below the stripping part (AT), V. evaporating at least a portion of the bottom product removed in step IV in (i) a main evaporator and (ii) at least one downstream re-evaporator operated at a higher temperature than that of the main evaporator down to a residual aromatic amine content in the outflow of the re-evaporator of from 0 to 98 percent by weight, and VI. recycling completely any gas phase obtained in step V and partially recycling any liquid obtained in step V into the column, either below or above the stripping part, and partial or complete sluicing out of the liquid phase obtained in the re-evaporator.