Process for the purification of aromatic amines

US8455691B2 · kind B2 · utility

Assignee

• Bayer MaterialScience AG · DE

Inventors

• Knut Sommer · Krefeld, DE
• Franz-Ulrich Gehlen · Krefeld, DE
• Peter Lehner · Baytown, US
• Andre Düx · Bogen, DE
• Benie Marotz · Mülheim an der Ruhr, DE

Key dates

• Filing date: Aug 15, 2008
• Grant date: Jun 4, 2013
• Expiry date: Oct 8, 2031

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C07C209/84
• WIPO field: Organic fine chemistry
• WIPO sector: Chemistry

Abstract

Aromatic amines which have been obtained by reduction of aromatic nitro compounds are purified by mixing the crude amine obtained after phase separation with an aqueous, alkali metal hydroxide solution and subsequent distillation of this mixture over a distillation column. The distillation column has at least an upper and a lower rectifying part and a stripping part. The bottom product of the distillation column is partly to completely sluiced out and is partly evaporated in a main evaporator and at least one downstream re-evaporator and partly recycled back into the column.