Bayer Materialscience Ag

Bayer Aktiengesellschaft

Rudolf Uchdorf

Fritz Pohl

Richard Adamson

Daniel Koch

Stefan Wershofen

Hans-Georg Pirkl

Torsten Hagen

Berthold Keggenhoff

Gerhard Wegener

Stephan Klein

Christine Mendoza-Frohn

Heinz-Herbert Müller

Jeffrey S Bolton

Dirk Grotjohann

Friedhelm K&auml;mper

Heinz-Herbert M&uuml;ller

Berthold Kegenhoff

Jeffrey Bolton

The invention provides an improved process for preparing diamines and polyamines from the diphenylmethane series by reacting aniline and formaldehyde in the presence of an acid catalyst, the improvement involving the aniline containing less than about 3 wt. % of diamines and polyamines from the diphenylmethane series, based on the weight of the aniline.

Process for preparing diamines and polyamines from the diphenylmethane series

The present invention relates to a process for the production of mixtures of di- and polyamines of the diphenylmethane series (MDA) containing less than 1,000 ppm of water and less than 200 ppm of aniline by reaction of aniline and formaldehyde in the presence of acid catalysts and subsequent separation of the acid catalyst and subsequent distillative separation of water and aniline in an at least a two-stage distillation including a flash evaporation and subsequent cooling.

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

The invention provides a process for the preparation of polyamines of the diphenylmethane series. This process comprises

Process for the preparation of polyamines of the diphenylmethane series at a low degree of protonation

The present invention concerns a process for the production of methylenedianiline (MDA) having a high monomer content.

Method for production of diaminodiphenylmethanes

Polyisocyanates of the diphenyl methane series having reduced color values are obtained by a) reacting aniline and formaldehyde in the presence of an acid catalyst to form a polyamine, b) neutralizing the reaction mixture containing polyamine with a base, c) separating the neutralized mixture into the aqueous and the organic phases, d) adding a base to the organic phase and then e) phosgenating the resulting polyamine to produce the corresponding polyisocyanate.

Process for producing polyisocyanates of the diphenyl methane series having a reduced color value

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Shanghai, China

Rudolf Uchdorf