US2553992A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Purifying dehydroacetic acid by distillation with glycol compounds
Assignee: Dow Chemical Co
•
Filing: 1950-02-01
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Granted: 1951-05-22
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Expires: 1970-02-01
Abstract
No abstract record available.
Inventors
- 👤 Glenn C Wiggins
- 👤 Wilbur E Johnson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 07:40
CPC Classifications
C; C07; C07D; C07D309/00; C07D309/34; C07D309/36
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
136 words
THE METHOD OF SEPARATING DEHYDROACETIC ACID FROM DIFFICULTLY REMOVABLE IMPURITIES WHICH COMPRISES CO-DISTILLING A MIXTURE CONSISTING OF IMPURE DEHYDROACETIC ACID AND A GLYCOL COMPOUND SELECTED FROM THE CLASS CONSISTING OF DI-ETHYLENE GLYCOL, TRI-ETHYLENE GLYCOL, TRI-PROPYLENE GLYCOL AND THE MONO-ALKYL ESTERS OF THE LATTER TWO GLYCOLS WHICH ETHERS HAVE BOILING POINTS AT ATMOSPHERIC PRESSURE BETWEEN 235* AND 280* C. AND IN WHICH THE ETHERIFYING ALKYL GROUP HAS FROM 1 TO 4 CARBON ATOMS, INCLUSIVE, THERE BEING INITIALLY FROM 1 TO 5 PARTS BY WEIGHT OF THE GLYCOL COMPOUND FOR EACH PART OF THE DEHYDROACETIC ACID, MAINTAINING THE DISTILLATION TEMPERATURE IN THE RANGE FROM 60* C. AT 1 MM. PRESSURE TO 150* C. AT 15 MM. PRESSURE, COOLING THE DISTILLATE TO A CRYSTALLIZATION TEMPERATURE UNTIL THE DEHYDROACETIC ACID CRYSTALLIZES THEREFROM, AND RECOVERING DEHYDROACETIC ACID FROM THE GLYCOL COMPOUND.
Claim 2
Independent Claim
136 words
THE METHOD OF SEPARATING DEHYDROACETIC ACID FROM DIFFICULTLY REMOVABLE IMPURITIES WHICH COMPRISES CO-DISTILLING A MIXTURE CONSISTING OF IMPURE DEHYDROACETIC ACID AND A GLYCOL COMPOUND SELECTED FROM THE CLASS CONSISTING OF DI-ETHYLENE GLYCOL, TRI-ETHYLENE GLYCOL, TRI-PROPYLENE GLYCOL AND THE MONO-ALKYL ESTERS OF THE LATTER TWO GLYCOLS WHICH ETHERS HAVE BOILING POINTS AT ATMOSPHERIC PRESSURE BETWEEN 235* AND 280* C. AND IN WHICH THE ETHERIFYING ALKYL GROUP HAS FROM 1 TO 4 CARBON ATOMS, INCLUSIVE, THERE BEING INITIALLY FROM 1 TO 5 PARTS BY WEIGHT OF THE GLYCOL COMPOUND FOR EACH PART OF THE DEHYDROACETIC ACID, MAINTAINING THE DISTILLATION TEMPERATURE IN THE RANGE FROM 60* C. AT 1 MM. PRESSURE TO 150* C. AT 15 MM. PRESSURE, COOLING THE DISTILLATE TO A CRYSTALLIZATION TEMPERATURE UNTIL THE DEHYDROACETIC ACID CRYSTALLIZES THEREFROM, AND RECOVERING DEHYDROACETIC ACID FROM THE GLYCOL COMPOUND.
References Cited (Backward Citations)
US2229204A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1954-05-21 | 1954-11-20 | 1955-05-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1958-05-21 | 1958-11-20 | 1959-05-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1962-05-21 | 1962-11-20 | 1963-05-22 | $7700.00 | Window Closed / Lapsed |