Patent US4252737A successfully refreshed from Google Patents.
US4252737A
Expired / Lapsed
US
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Process for the production of aromatic carbonic acid esters
Assignee: Bayer AG
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Filing: 1980-01-10
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Granted: 1981-02-24
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Expires: 2000-01-10
Abstract
Abstract A process for the production of aromatic carbonic acid esters by transesterifying a mixture of dimethylcarbonamate/methanol and a methanol-immiscible azeotrope former for methanol with phenols in the presence of transesterification catalysts.
Inventors
- 👤 Heinrich Krimm
- 👤 Hans-Josef Buysch
- 👤 Hans Rudolph
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 12:17
CPC Classifications
C; C07; C07C; C07C68/00; C07C68/06
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
66 words
A process for the production of aromatic carbonic acid esters by transesterification comprising (a) mixing a phenol, dimethyl carbonate, methanol, a transesterification catalyst and a methanol-immiscible hydrocarbon azeotrope former for methanol selected from the group consisting of pentane, hexane, heptane, octane, isooctane, and mixtures thereof; (b) transesterifying the dimethyl carbonate with the phenol; and (c) simultaneous with (b) removing methanol by distilling off the methanol/hydrocarbon azeotrope.
Claim 2
Dependent Claim
66 words
A process for the production of aromatic carbonic acid esters by transesterification comprising (a) mixing a phenol, dimethyl carbonate, methanol, a transesterification catalyst and a methanol-immiscible hydrocarbon azeotrope former for methanol selected from the group consisting of pentane, hexane, heptane, octane, isooctane, and mixtures thereof; (b) transesterifying the dimethyl carbonate with the phenol; and (c) simultaneous with (b) removing methanol by distilling off the methanol/hydrocarbon azeotrope.
Claim 3
Dependent Claim
28 words
A process according to claim 1 wherein the source of dimethyl carbonate and methanol mixed in (a) is a mixture of 10-95% dimethyl carbonate with the remainder methanol.
Claim 4
Dependent Claim
21 words
A process according to claim 2 wherein the dimethyl carbonate/methanol mixture is a dimethyl carbonate/methanol azeotrope containing about 30% dimethyl carbonate.
Claim 5
Dependent Claim
21 words
A process as claimed in claim 1, wherein the transesterification is carried out at temperature of from 50° to 250° C.
References Cited (Backward Citations)
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Cited
GB772627A
Cited
GB808488A
Cited
US3011954A
Cited
US3239572A
Cited
US3431181A
Cited
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Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-02-24 | 1984-08-25 | 1985-02-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-02-24 | 1988-08-25 | 1989-02-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-02-24 | 1992-08-25 | 1993-02-24 | $7700.00 | Window Closed / Lapsed |