US3624145A
Expired / Lapsed
US
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Purification of terephthalic acid by liquid-liquid extraction
Assignee: EIDP Inc
•
Filing: 1969-02-17
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Granted: 1971-11-30
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Expires: 1989-02-17
Abstract
Abstract Purifying terephthalic acid by liquid-liquid extraction wherein an aqueous solution of crude terephthalic acid is contacted with a water-immiscible liquid organic extractant inert to terephthalic acid at elevated temperatures to form an aqueous phase and organic phase, subsequently separating the two phases and recovering purified terephthalic acid.
Inventors
- 👤 Marvin S Brinn
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 21:53
CPC Classifications
C; C07; C07C; C07C51/00; C07C51/42; C07C51/48
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
12 words
A process of claim 1 wherein the extractant is an aromatic hydrocarbon.
Claim 2
Dependent Claim
11 words
The process of claim 2 wherein the aromatic hydrocarbon is p-xylene.
Claim 3
Dependent Claim
19 words
A process of claim 3 wherein the weight ratio of terephthalic acid to water is from 1:2 to 1:10.
Claim 4
Dependent Claim
21 words
A process of claim 4 wherein the weight ratio of the aqueous phase to the organic phase is 1:1 to 1:5.
Claim 5
Dependent Claim
16 words
A process of claim 5 wherein the pressure employed during extracting is slightly above about autogenous.
Claim 6
Dependent Claim
18 words
A process of claim 6 wherein the aqueous phase is segregated from the organic phase by gravitational settling.
Claim 7
Dependent Claim
19 words
A process of claim 6 wherein the crude terephthalic acid is contacted with p-xylene in a countercurrent extraction system.
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) | 1974-11-29 | 1975-05-31 | 1975-11-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-11-29 | 1979-05-31 | 1979-11-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-11-29 | 1983-05-31 | 1983-11-30 | $7700.00 | Window Closed / Lapsed |