Patent attributes
The present invention relates to a process for preparation of polycarbonates with weight-average molar mass MW≧230,000 g/mol and with ≦2% by weight content of cyclic compounds, including the following steps:(a) reaction of at least one oxirane with carbon dioxide in the presence of a metal-polycarboxylic acid compound in an aprotic, non-water-miscible solvent at a temperature of from 40 to 120° C. and at a pressure of from 1 to 100 bar, where the molar ratio of monomer to metal-polycarboxylic acid compound is ≧75,(b) addition of an aqueous solution of an inorganic acid to the reaction mixture once the reaction has ended,(c) removal of the aqueous phase,(d) if appropriate, washing of the remaining organic phase with water, and(e) devolatilization and drying of the resultant slurry of the polycarbonate in the aprotic, non-water-miscible solvent,and to the polycarbonate prepared via the process, and also to the use of the polycarbonate.
