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US 5,399,736 AGranted
Process for the preparation of highly pure aromatic diurethanes and/or polyurethanes
AssigneeBayer Aktiengesellschaft
InventorsWolfgang Friederichs, Stefan Penninger, Stefan Wershofen
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Abstract
This invention relates to a process for the preparation of highly pure aromatic diurethanes and/or polyurethanes by reaction of the corresponding aromatic diamines and/or polyamines with unsubstituted carbamates with the release of ammonia. The reaction is carried out in the presence of excess carbamates. The resultant reaction mixture is freed from any solvents used, and the formed aromatic diurethanes and/or polyurethanes are purified by extraction with water.
Claims17
A process for the preparation of highly pure aromatic diurethanes and/or polyurethanes comprising the steps of
- a) reacting
- 1) the corresponding aromatic diamines and/or polyamines, with
- 2) an excess of unsubstituted carbamates, with the release of ammonia,
- b) removing any solvents from the reaction mixture which were used in the reaction, and
- c) purifying the resultant aromatic diurethanes and/or polyurethanes by extraction with water.
2 more elements
Dependencies are inferred from the claim text.