US3215734A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for purification of terephthalic acid
Assignee: Chemische Werke Witten GmbH
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Filing: 1961-06-14
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Granted: 1965-11-02
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Expires: 1981-06-14
Abstract
No abstract record available.
Inventors
- 👤 Katzschmann Ewald
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 02:33
CPC Classifications
C; C07; C07C; C07C51/00; C07C51/42; C07C51/43; C07C51/02; C07C51/487
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
99 words
A PROCESS FOR THE RECOVERY OF A SUBSTANTIALLY PURE AMMONIUM SALT OF TEREPHTHALIC ACID FROM AN IMPURE TEREPHTHALIC ACID PREPARED BY THE OXIDATION OF P-XYLENE WITH AN AGENT SELECTED FROM THE GROUP CONSISTING OF AIR AND NITRIC ACID WHICH COMPRISES SUSPENDING THE IMPURE ACID IN A MIXTURE OF DIMETHYL FORMAMIDE AND WATER, ADDING SUFFICIENT AMMONIA TO THE SUSPENSION TO NEUTRALIZE THE SUSPENDED ACID AND FORM A SOLUTION PRECIPITATING THE AMMONIA SALT OF TEREPHTHALIC ACID FROM THE SOLUTION FORMED BY INCREASING THE RATIO OF DIMETHYL FORMAMIDE TO WATER IN SAID SOLUTION, AND SEPARATING THE PRECIPITATED AMMONIUM SALT FROM THE SOLUTION.
Claim 2
Dependent Claim
99 words
A PROCESS FOR THE RECOVERY OF A SUBSTANTIALLY PURE AMMONIUM SALT OF TEREPHTHALIC ACID FROM AN IMPURE TEREPHTHALIC ACID PREPARED BY THE OXIDATION OF P-XYLENE WITH AN AGENT SELECTED FROM THE GROUP CONSISTING OF AIR AND NITRIC ACID WHICH COMPRISES SUSPENDING THE IMPURE ACID IN A MIXTURE OF DIMETHYL FORMAMIDE AND WATER, ADDING SUFFICIENT AMMONIA TO THE SUSPENSION TO NEUTRALIZE THE SUSPENDED ACID AND FORM A SOLUTION PRECIPITATING THE AMMONIA SALT OF TEREPHTHALIC ACID FROM THE SOLUTION FORMED BY INCREASING THE RATIO OF DIMETHYL FORMAMIDE TO WATER IN SAID SOLUTION, AND SEPARATING THE PRECIPITATED AMMONIUM SALT FROM THE SOLUTION.
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) | 1968-11-01 | 1969-05-03 | 1969-11-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1972-11-01 | 1973-05-03 | 1973-11-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1976-11-01 | 1977-05-03 | 1977-11-02 | $7700.00 | Window Closed / Lapsed |