US4255557A
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US
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Preparing polycarbonate oligomers by reacting phosgene with an aqueous solution containing a salt of a dihydric phenol in an organic solvent which comprises previously cooling the aqueous solution and carrying out the reaction at a low temperature
Assignee: Mitsubishi Gas Chemical Co Inc
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Filing: 1979-10-03
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Granted: 1981-03-10
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Expires: 1999-10-03
Abstract
Abstract A process for preparing polycarbonate oligomers by reacting phosgene with an alkaline aqueous solution containing an alkali metal salt or alkaline earth metal salt of a dihydric phenol in the presence of an inert organic solvent, which comprises previously cooling said alkaline aqueous solution to not higher than 0° C., reacting the cooled aqueous solution with phosgene to perform a phosgenation reaction and also to absorb the heat of the phosgenation reaction by the quantity of heat that said cooled aqueous solution has, thereby to adjust the phosgenation reaction system substantially to not higher than 10° C., and then oligomerizing the phosgenation product at a temperature of 15° C. or higher.
Inventors
- 👤 Takeaki Megumi
- 👤 Hiroyuki Yoshizaki
- 👤 Sigeo Kondoh
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 13:28
CPC Classifications
C; C08; C08G; C08G64/00; C08G64/20; C08G64/22; C08G64/24; C07; C07C; C07C68/00; C07C68/02
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
111 words
A process for preparing polycarbonate oligomers by reacting phosgene with an alkaline aqueous solution containing an alkali metal salt or alkaline earth metal salt of a dihydric phenol in the presence of an inert organic solvent, which comprises previously cooling said alkaline aqueous solution to not higher than 0° C., reacting the cooled aqueous solution with phosgene to perform a phosgenation reaction and also to absorb the heat of the phosgenation reaction by the quantity of heat that said cooled aqueous solution has, thereby to adjust the phosgenation reaction system substantially to not higher than 10° C., and then oligomerizing the phosgenation product at a temperature of 15° C. or higher.
Claim 2
Dependent Claim
111 words
A process for preparing polycarbonate oligomers by reacting phosgene with an alkaline aqueous solution containing an alkali metal salt or alkaline earth metal salt of a dihydric phenol in the presence of an inert organic solvent, which comprises previously cooling said alkaline aqueous solution to not higher than 0° C., reacting the cooled aqueous solution with phosgene to perform a phosgenation reaction and also to absorb the heat of the phosgenation reaction by the quantity of heat that said cooled aqueous solution has, thereby to adjust the phosgenation reaction system substantially to not higher than 10° C., and then oligomerizing the phosgenation product at a temperature of 15° C. or higher.
Claim 3
Dependent Claim
48 words
A process as described in claim 1, wherein said alkaline aqueous solution previously cooled to not higher than 0° C. is a cold aqueous solution made by partially freezing said alkaline aqueous solution or a cold aqueous solution made by rendering ice co-present in said alkaline aqueous solution.
Claim 4
Dependent Claim
19 words
A process as described in claim 1, wherein said dihydric phenol is at least one member selected from bis(4-hydroxyphenyl)alkanes.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-03-09 | 1984-09-08 | 1985-03-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-03-09 | 1988-09-08 | 1989-03-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-03-09 | 1992-09-08 | 1993-03-10 | $7700.00 | Window Closed / Lapsed |