Basf Aktiengesellschaft

Basf Se Corporation

Robert Reinhardt

Helmut Reichelt

Eckhard Stroefer

Thomas Gessner

Heiner Schelling

Kai Thiele

Stefan Adams

Daniel Breuninger

Michael Zoellinger

Peter Van Den Abeel

Roland Merger

Markus Kraemer

Gunter-Rudolf Schr&ouml;der

Stephan Heiser

Oliver Buchholz

Michael Dorner

The invention relates to a process for preparing methylenediphenyldiamine (MDA) by reacting formaldehyde and aniline in the presence of an acidic catalyst, wherein the oxygen content in the process for preparing MDA is &#x3c;10 000 ppm, based on all compounds present in the process. The invention further relates to the phosgenation of MDA to methylenediphenyl diisocyanate (MDI).

Method for producing color-stable MDA and MDI

Process for preparing aqueous solutions of cationic di- and triarylmethane dyes by the aqueous dye solution, which contains organic solvents, being concentrated by nanofiltration and optionally diluted with water.

Method for producing aqueous solutions of cationic diarylmethane colorants and triarylmethane colorants

A process for preparing carbocyclic m-aminohydroxyaromatics comprises reacting the corresponding o-- or m-halohydroxyaromatics or metal salts thereof with primary or secondary amines in the presence of a base and in the presence or absence of a diluent.

Preparation of carbocylic M-aminohydroxyaromatics

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Meckenheim, Germany

Robert Reinhardt