process for the production of polyaminen

摘要

This invention relates to a new and improved process for the preparation of polyamines based on diphenylmethane by acid condensation of aromatic amines with formaldehyde followed by processing of the condensation mixture. Compared with similar processes known in the art, the process according to the invention combines the advantage of requiring less distillation for processing the reaction mixture with the advantage of a wide scope for variation of the composition of the product finally obtained, particularly with regard to its concentration of 2,4'-isomers and greatly reduced concentration of 2,2'-isomers. More particularly, the instant invention is directed to a process for the preparation of multinuclear aromatic polyamines by condensation of aromatic amines with formaldehyde in the presence of aqueous acid catalysts in a condensation reaction carried out in at least two stages, followed by neutralization of the catalyst and recovery of aromatic polyamines characterized in that free amine is removed from the condensation reaction mixture by means of a hydrophobic solvent after the first condensation stage and before the final condensation stage, and the amine thus removed is returned to the aqueous, catalyst-containing phase by returning the resulting amine-containing solvent phase to said aqueous phase before the first condensation stage.