Patent ID: 8106144

Claim:
A process for producing polycarbonate comprising: a) producing phosgene by reacting chlorine with carbon monoxide; b) reacting the phosgene formed in step a) with at least one bisphenol in the presence of an aqueous alkali metal containing base to form a polycarbonate and an alkali metal chloride-containing reaction waste water solution; c) separating off and working up the polycarbonate formed in step b) from the alkali metal chloride-containing reaction waste water solution; e) distilling at least a portion of the alkali metal chloride-containing reaction waste water solution remaining after step c) via osmotic membrane distillation to obtain an enriched alkali metal chloride-containing solution; f) electrochemically oxidating of at least a portion of the alkali metal chloride-containing solution from e) to obtain chlorine, an alkali metal hydroxide solution and, optionally, hydrogen.