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US 6,548,691 B2Granted
Process for producing carbonic acid diaryl ester
AssigneeBayer Aktiengesellscaft
InventorsWolfgang Alewelt, Steffen Kühling
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Abstract
An improvement to the interfacial boundary process for producing carbonic acid diaryl esters is disclosed. In the two-stage process that entails phosgene and monophenols reaction in an inert solvent, in the presence of alkali and in the presence of a nitrogen base catalyst, the improvement comprising maintaining a temperature below 50° C. in the first and second stages.
Claims6
In the interfacial boundary process for producing carbonic acid diaryl esters from phosgene and monophenols in an inert organic solvent, in the presence of an alkaline solution and a nitrogen base catalyst, the process including:
- (i) a first stage wherein phosgene, said inert organic solvent and phenol in solution are combined to form a material system having a pH of 11.0 to 12.0;
- and
- (ii) a second stage wherein the reaction to form carbonic acid diaryt ester is completed,
- the improvement comprising maintaining a temperature below 50° C. in each of said first and second stages, and wherein the carbonic acid diaryl esters have a urethane content of less than 100 ppm.
1 more element
Dependencies are inferred from the claim text.