Process for the preparation of polyamines

US4087459A · kind A · utility

Assignee

• BAYER HEALTHCARE LLC · DE

Inventors

• Hartmut Knofel · Odenthal, DE
• Gunther Ellendt · Krefeld, DE

Key dates

• Filing date: Jun 16, 1976
• Grant date: May 2, 1978
• Expiry date: Jun 16, 1996

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C07C209/78
• WIPO field: Organic fine chemistry
• WIPO sector: Chemistry

Abstract

The instant invention is directed to a process for the preparation of multinuclear aromatic polyamines by the condensation of aniline with formaldehyde in the presence of water and acid catalysts, in which the completely reacted aqueous condensation mixture is extracted with a hydrophobic solvent in extraction stage (I), optionally with the addition of aniline, the resulting solvent phase is worked-up in known manner to isolate the polyamine and the aqueous phase is recycled to the beginning of the process, the improvement characterised in that before the aqueous phase is returned to the beginning of the process, it is extracted in one or more separate extractors (II) with a hydrophobic solvent which may contain aniline and/or aniline/formaldehyde condensates with an increased proportion of ortho-isomers, the resulting solvent phase or phases is or are extracted with the aqueous acid condensation mixture in one or more separate extractors (III) at any one or more points after the first condensation stage and before the main extraction stage (I), and the resulting solvent phase or phases is or are returned to extractor or extractors (II).