METHOD FOR PRODUCING MDI, ESPECIALLY 2,4'-MDI

MDI is prepared by a process comprising the following steps: A) reaction of aniline and formaldehyde in the presence of an acid to give methylene(diphenyldiamines) and polymethylenepolyphenylenepolyamines, the molar ratio of acid to amine being not more than 0.2, B) reaction of the mixture obtained...

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Bibliographische Detailangaben
Hauptverfasser:	POHL, SIEGMUND, BETTENDORF, CARL, BRUCHMANN, BERND, THIELE, KAI, REIF, MARTIN, PLAUMANN, HEINZ
Format:	Patent
Sprache:	eng ; fre ; ger
Schlagworte:	ACYCLIC OR CARBOCYCLIC COMPOUNDS APPARATUS THEREFOR CHEMISTRY COMPOSITIONS BASED THEREON GENERAL METHODS OF ORGANIC CHEMISTRY MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONSONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS METALLURGY ORGANIC CHEMISTRY ORGANIC MACROMOLECULAR COMPOUNDS THEIR PREPARATION OR CHEMICAL WORKING-UP
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Beschreibung
Zusammenfassung:	MDI is prepared by a process comprising the following steps: A) reaction of aniline and formaldehyde in the presence of an acid to give methylene(diphenyldiamines) and polymethylenepolyphenylenepolyamines, the molar ratio of acid to amine being not more than 0.2, B) reaction of the mixture obtained in step A) with phosgene to give methylene(diphenyl diisocyanates) and polymethylenepolyphenylene polyisocyanates, C) separation of the mixture obtained in step B) into monomeric MDI and polymeric MDI and D) separation of the monomeric MDI obtained in step C) by isolating 2,4'-MDI.