Process for the production of poly(O-alkylurethanes) of the diphenyl methane series
AssigneeBayer Aktiengesellschaft
InventorsGunter Hammen, Thomas Schieb, Stefan Wershofen
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Abstract
The present invention relates to an improved process for the production of monomeric and polymeric poly(O-alkylurethanes) of the diphenyl methane series. The process comprises the reaction of the corresponding amines with dialkyl carbonates in the presence of a catalyst, followed by the isolation of the products in a highly pure form. The invention also relates to the use of the produced monomeric and polymeric poly(O-alkylurethanes) for the production of the corresponding isocyanates.
Claims6
A process for the production of monomeric and/or polymeric poly(O-alkylurethanes) of the diphenyl methane series comprising reacting
- a) amines selected from the group consisting of 4,4'-diaminodiphenyl methane, 2,4'-diaminodiphenyl methane, 2,2'-diaminodiphenyl methane, higher homologs thereof formed in the condensation of aniline with formaldehyde, and mixtures thereof;
- with
- b) a dialkyl carbonate containing from 1 to 2 carbon atoms per alkyl group;
- in the presence of
- c) a catalyst;
- wherein said dialkyl carbonate is present in a quantity such that the molar ratio of dialkyl carbonate to amine is at least 40:1, and the formed monomeric and/or polymeric poly(O-alkylurethanes) crystallize out in a highly pure form upon cooling.
Dependencies are inferred from the claim text.