Process for the preparation of di- and polyamines of the diphenylmethane series

摘要

The invention relates to a method for producing diamines and polyamines of the diphenylmethane series in which, by using a coalescence auxiliary in the phase separation of the process product obtained in the scrubbing of the neutralized crude product, the fraction of water and thus also of water-soluble impurities in the organic MDA-containing phase is reduced. According to the invention, the coalescence auxiliary used is a filter bed made of coalescence fiber material. The di- and polyamines of the diphenylmethane series obtained after distillative purification of this MDA-containing organic phase are exceptionally suitable for the preparation of the corresponding isocyanates.

主权项

1. A process for the preparation of di- and polyamines of the diphenylmethane series, comprising:
a) reacting aniline and formaldehyde in the presence of an acidic catalyst to give a reaction mixture comprising di- and polyamines of the diphenylmethane series, b) neutralizing the reaction mixture comprising di- and polyamines of the diphenylmethane series, c) separating the neutralized reaction mixture comprising di- and polyamines of the diphenylmethane series in a separation container into an organic phase (1) comprising di- and polyamines of the diphenylmethane series and an aqueous phase, d) further purifying the organic phase (1) comprising di- and polyamines of the diphenylmethane series in a washing container with washing liquid, e) freeing the mixture obtained in step d) from aqueous constituents, giving an organic phase (2) comprising di- and polyamines of the diphenylmethane series, and f) freeing the organic phase (2) comprising di- and polyamines of the diphenylmethane series distillatively from water and aniline, wherein the freeing of the aqueous constituents in step e) comprises:
e.1) separating the mixture obtained in step (d) in a separating container into an aqueous and an organic phase (2a), and thene.2) passing the organic phase (2a) obtained in step e.1) through a filter bed made of coalescence fiber material and then separating the organic phase obtained thereby into an aqueous phase and the organic phase (2).