Patent US4813757A successfully refreshed from Google Patents.
Patent US2816922A successfully refreshed from Google Patents.
US2816922A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Production of fumaric acid
Assignee: California Research LLC
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Filing: 1954-05-17
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Granted: 1957-12-17
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Expires: 1974-05-17
Abstract
No abstract record available.
Inventors
- 👤 Robert W Stephenson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 18:51
CPC Classifications
C; C07; C07C; C07C51/00; C07C51/347; C07C51/353
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
166 words
A PROCESS FOR NONCATALYTICALLY CONVERTING MALEIC ACID CONTAINED IN RELATIVELY DILUTE AQUEOUS MALEIC ACID SOLUTIONS CONTAINING UP TO ABOUT 30% BY WEIGHT OF MALEIC ACID TO FUMARIC ACID, WHICH COMPRISES HEATING THE DILUTE MALEIC ACID TO AN ELEVATED TEMPERATURE BELOW ABOUT 250*F IN A CONCENTRATION ZONE TO EVAPORATE WATER FROM THE DILUTE SOLUTION AND PRODUCE A CONCENTRATED MALEIC ACID SOLUTION CONTAINING ABOUT 70 TO 90% BY WEIGHT OF MALEIC ACID, HEATING THE CONCENTRATED MALEIC ACID TO A TEMPERATURE ABOVE 250*F. AND BELOW ABOUT 400* F. IN A CONVERSION ZONE TO PRODUCE A SLURRY OF FUMARIC ACID IN AQUEOUS MALEIC ACID, WITHDRAWING A VAPOR STEAM COMPRISING STEAM AND MALEIC ANHYDRIDE FROM THE CONVERSION ZONE AND PASSING IT INTO THE CONCENTRATION ZONE, DILUTING THE WITHDRAWN SLURRY WITH CONVERSION ZONE, DILUTING THE WITH-EPARATING THE DILUTED SLURRY INTO A LIQUID PHASE COMPRISING ARATING THE DILUTED SLURRY INTO A LIQUID PHASE COMPRISING AQUEOUS MALEIC ACID AND A SOLID PHASE COMPRISING FUMARIC ACID AND RETURNING THE LIQUID PHASE TO THE CONVERSION ZONE.
Claim 2
Dependent Claim
166 words
A PROCESS FOR NONCATALYTICALLY CONVERTING MALEIC ACID CONTAINED IN RELATIVELY DILUTE AQUEOUS MALEIC ACID SOLUTIONS CONTAINING UP TO ABOUT 30% BY WEIGHT OF MALEIC ACID TO FUMARIC ACID, WHICH COMPRISES HEATING THE DILUTE MALEIC ACID TO AN ELEVATED TEMPERATURE BELOW ABOUT 250*F IN A CONCENTRATION ZONE TO EVAPORATE WATER FROM THE DILUTE SOLUTION AND PRODUCE A CONCENTRATED MALEIC ACID SOLUTION CONTAINING ABOUT 70 TO 90% BY WEIGHT OF MALEIC ACID, HEATING THE CONCENTRATED MALEIC ACID TO A TEMPERATURE ABOVE 250*F. AND BELOW ABOUT 400* F. IN A CONVERSION ZONE TO PRODUCE A SLURRY OF FUMARIC ACID IN AQUEOUS MALEIC ACID, WITHDRAWING A VAPOR STEAM COMPRISING STEAM AND MALEIC ANHYDRIDE FROM THE CONVERSION ZONE AND PASSING IT INTO THE CONCENTRATION ZONE, DILUTING THE WITHDRAWN SLURRY WITH CONVERSION ZONE, DILUTING THE WITH-EPARATING THE DILUTED SLURRY INTO A LIQUID PHASE COMPRISING ARATING THE DILUTED SLURRY INTO A LIQUID PHASE COMPRISING AQUEOUS MALEIC ACID AND A SOLID PHASE COMPRISING FUMARIC ACID AND RETURNING THE LIQUID PHASE TO THE CONVERSION ZONE.
References Cited (Backward Citations)
US2208519A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1960-12-16 | 1961-06-17 | 1961-12-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1964-12-16 | 1965-06-17 | 1965-12-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1968-12-16 | 1969-06-17 | 1969-12-17 | $7700.00 | Window Closed / Lapsed |