US2510852A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for purifying phthalic anhydride
Assignee: Honeywell International Inc
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Filing: 1948-03-19
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Granted: 1950-06-06
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Expires: 1968-03-19
Abstract
No abstract record available.
Inventors
- 👤 Maurice E Bailey
- 👤 John K Evans
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 02:14
CPC Classifications
C; C07; C07C; C07C51/00; C07C51/54; C07C51/573
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
103 words
IN A PROCESS FOR THE PURIFICATION OF PHTHALIC ANHYDRIDE OBTAINED BY CATALYTIC OXIDATION OF NAPHTHALENE VAPORS, AND CONTAINING NAPHTIOQUINONE TYPE IMPURITIES, THE STEPS WHICH COMPRISE ADDING THERETO A QUANTITY BETWEEN ABOUT 0.25 AND 1.0% BY WEIGHT BASED ON THE PHTHALIC ANHYDRIDE, OF MALEIC ANHYDRIDE, HEATING THE MIXTURE AT ABOUT 180*C. FOR A PERIOD BETWEEN 1 AND 2 HOURS, THEREAFTER ADDING BETWEEN ABOUT 0.2% AND 1% OF SODIUM BISULFITE BASED ON THE WEIGHT OF THE PHTHALIC ANHYDRIDE AND CONTINUING THE HEATING UNDER REFLUXING CONDITIONS FOR AN ADDITIONAL PERIOD OF BETWEEN ABOUT 8 AND 9 HOURS, AND THEREAFTER RECOVERING THE PURIFIED PHTHALIC ANHYDRIDE BY VIOLATILIZATION.
Claim 2
Dependent Claim
103 words
IN A PROCESS FOR THE PURIFICATION OF PHTHALIC ANHYDRIDE OBTAINED BY CATALYTIC OXIDATION OF NAPHTHALENE VAPORS, AND CONTAINING NAPHTIOQUINONE TYPE IMPURITIES, THE STEPS WHICH COMPRISE ADDING THERETO A QUANTITY BETWEEN ABOUT 0.25 AND 1.0% BY WEIGHT BASED ON THE PHTHALIC ANHYDRIDE, OF MALEIC ANHYDRIDE, HEATING THE MIXTURE AT ABOUT 180*C. FOR A PERIOD BETWEEN 1 AND 2 HOURS, THEREAFTER ADDING BETWEEN ABOUT 0.2% AND 1% OF SODIUM BISULFITE BASED ON THE WEIGHT OF THE PHTHALIC ANHYDRIDE AND CONTINUING THE HEATING UNDER REFLUXING CONDITIONS FOR AN ADDITIONAL PERIOD OF BETWEEN ABOUT 8 AND 9 HOURS, AND THEREAFTER RECOVERING THE PURIFIED PHTHALIC ANHYDRIDE BY VIOLATILIZATION.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1953-06-05 | 1953-12-05 | 1954-06-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1957-06-05 | 1957-12-05 | 1958-06-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1961-06-05 | 1961-12-05 | 1962-06-06 | $7700.00 | Window Closed / Lapsed |