Abstract:
The invention relates to a method for obtaining a dialkyl carbonate and an alkylene glycol from a material flow containing dialkyl carbonate, alkylene carbonate, alkylene glycol, and alcohol, said method having the following steps: (a) separating a material flow (5) containing dialkyl carbonate and alkylene glycol in the form of a heteroazeotrope from the material flow containing dialkyl carbonate, alkylene carbonate, alkylene glycol, and alcohol in a distillative manner in a first distillation stage (1), and (b) separating the material flow (5) containing dialkyl carbonate and alkylene glycol in the form of a heteroazeotrope into a first raw product flow (27) which substantially contains dialkyl carbonate and a second raw product flow (29) which substantially contains alkylene glycol in a device for the purpose of a phase separation (25).
Abstract:
The invention provides a multistage process for continuously preparing organic polyisocyanates, preferably diisocyanates, more preferably aliphatic or cycloaliphatic diisocyanates, by reacting the corresponding organic polyamines with carbonic acid derivatives and alcohols to give low molecular weight monomeric polyurethanes and cleaving the latter. The invention further provides a corresponding preparation process in which the polyisocyanates prepared and unutilizable residues are removed at particular reaction stages, and reusable by-products and intermediates are recycled into preceding stages.
Abstract:
The invention relates to a method for producing isocyanates by thermally splitting carbamates, a carbamate splitting gas comprising the corresponding isocyanate and the corresponding alcohol being obtained, the invention being characterized in that the carbamate splitting gas is quenched in the presence of an ether functioning as an inhibitor for the back reaction of the isocyanate and the alcohol.
Abstract:
The invention relates to a method for producing triethylenetetramine that is substituted with at least one methyl group (Me-TETA or methyl-substituted TETA compounds). Me-TETA is produced by hydrogenating biscyanomethyl imidazolidine (BCMI) in the presence of a catalyst. The present invention further relates to methyl-substituted TETA compounds as such. The present invention further relates to the use of methyl-substituted TETA compounds as an educt or intermediate product in the production of, for example, coatings or adhesives.