Process for purifying diaryl carbonates

Details Process for purifying diaryl carbonates Process for purifying diaryl carbonates

1993-06-29

1996-03-12

Manoharan, Virginia

Distillation: processes, separatory

With disparate physical separation

203 94, 203 98, 558274, B01D 314, C07C 6996

Patent

active

054983193

ABSTRACT:
Illustrated by the purification of diphenyl carbonate (DPC), diaryl carbonates are purified and freed of contaminants such as inorganic and organic chlorides, metal ions, iron components and color bodies. The process is a two-stage procedure starting with a water wash of the molten carbonate followed by distillation. Crude DPC is charged to the wash tank and is washed in the molten state three times. Fresh steam condensate is used for each wash which consists of a period of agitation followed by decantation then water removal. After the third wash, the molten DPC is transferred to a still for distillation. The rag layer which is formed at the water/DPC interface during washing is purged and not allowed to pass through to the still. A flash distillation is carried out under constant vacuum. Three overhead cuts are taken--lights, intermediate and product DPC depending on the temperature of the overhead vapor.

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