Method for producing diamines and polyamines of the diphenylmethane series

A process for the preparation of di- and polyamines of the diphenylmethane series, comprising:

• a) converting aniline and formaldehyde in the absence of an acidic catalyst to a reaction mixture comprising aminal and water,
• b) removing water at least in part from the reaction mixture obtained in step a), giving an organic phase (1) comprising the aminal,
• c) converting the organic aminal-comprising phase (1) obtained in step b) in the presence of an acidic catalyst, giving a reaction mixture comprising di- and polyamines of the diphenylmethane series, and
• d) neutralizing the reaction mixture comprising di- and polyamines of the diphenylmethane series obtained in step c) and then subjecting the neutralized reaction mixture to a work-up involving washing and distillation,
• wherein the separation of the water from the reaction mixture obtained in step a) comprises
• b.1) separating the reaction mixture obtained in step a) in a separating container into an aqueous and an organic phase (1a), and then
• b.2) passing the aqueous phase obtained in step b.1)
• through a filter bed of coalescence fiber material and
• then separating the aqueous phase obtained thereby into an aqueous phase and an organic phase (1b), and then
• b.3) combining the organic phase (1b) obtained in step b.2) with the organic phase (1a) obtained in step b.1) to give the organic phase (1).