Continuous production process of diarylcarbonates
Patent 5426207 Issued on June 20, 1995. Estimated Expiration Date: 
October 28, 2013. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.
October 28, 2013. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.Patent ReferencesProcess for the preparation of aromatic carbonates Process for the preparation of aromatic carbonates Diaryl carbonate process Process for the preparation of aromatic carbonates Process for continuously producing an aromatic carbonate Patent #: 5210268 InventorsAssigneeApplicationNo. 142125 filed on 10/28/1993US Classes:558/274Two benzene rings bonded directly to the -O-C(=O)O- group (i.e., diaryl carbonates)ExaminersPrimary: Lee, Mary C.Assistant: Ambrose, M. G. Attorney, Agent or FirmForeign Patent References
International ClassC07C 069/96AbstractA diaryl carbonate is produced by transesterification of a dialkyl carbonate, such as dimethyl carbonate, with an aromatic hydroxy compound, such as phenol, in three successive reaction zones. A transesterification catalyst, such as a titanate ester or ester mixture is used in each zone. Conditions are selected to maximize formation of alkyl aryl carbonate in the first and second reaction zones, while conversion to diaryl carbonate is favored in the third reaction zone. The vaporous mixture from the first two reaction zones is a mixture containing alkyl alcohol, dialkyl carbonate, alkyl aryl carbonate and aromatic hydroxy compound. This mixture is separated in an alkyl alcohol recovery zone by distillation in the distillation columns to produce useful recycle streams. The second of these distillation columns can be operated at a lower pressure than the first, thus enabling the heat of vaporization of this mixture to be used as the source of heat for the reboiler of the second distillation column of the alkyl alcohol recovery zone.Other References
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