PURPOSE: To obtain a highly pure aromatic diurethane and/or polyurethane by eliminating solvent and then extracting with water after aromatic diamine accompanied by release of ammonia and/or polyamine is reacted with excess unsubstituted carbamate.
CONSTITUTION: Aromatic diamine and/or polyamine reacted with unsubstituted carbamate while ammonia is released prepare the highly pure aromatic diurethane and/or polyurethane. At that time, substituted carbamate, preferably an excess amount of about 10-30 moles of carbamate per mole amino group of aromatic di- and/or poly-amine is used. After the reaction is completed, the solvent is separated and by-products, excess carbamate, unreacted di- and/or poly-amine are eliminated by extraction process with water. As unsubstituted carbamate, it is preferable to use those which are produced by reacting alcohol with urea at the site. This method has easy separation under relatively gentle process conditions and is advantageous because of only one-step process.
Stephan Penninger
Stefan Wershjofuen
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