US3328429A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Purification of crude phthalic anhydride
Assignee: Witco Corp
•
Filing: 1965-07-06
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Granted: 1967-06-27
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Expires: 1985-07-06
Abstract
No abstract record available.
Inventors
- 👤 Meinstein Siegfried
- 👤 Charles F Fuchs
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 19:14
CPC Classifications
C; C07; C07C; C07C51/00; C07C51/54; C07C51/573
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
99 words
A METHOD OF PURIFYING CRUDE PHTHALIC ANHYDRIDE WHICH COMPRISES PROVIDING A MIXTURE THEREOF WITH FROM ABOUT 0.01% TO BELOW 1%, BY WEIGHT OF SAID ANHYDRIDE, OF AN ALKALI METAL BOROHYDRIDE, AN ALKALINE EARTH METAL BOROHYDRIDE OR A QUATERNARY AMMONIUM BOROHYDRIDE CORRESPONDING TO THE FORMULA (R4)$N WHERE R ARE THE SAME OR DIFFERENT HYDROCARBON RADICALS SELECTED FROM THE GROUP CONSISTING OF METHYL, ETHYL, PROPYL, ISOPROPYL, BUTYL, ISOBUTYL AND CYCLOHEXYL, OR AN ALKALI METAL HYDRIDE OR ALKALINE EARTH METAL HYDRIDE, HEATING SAID MIXTURE AT A TEMPERATURE ABOVE 270 DEGREES C. FOR SEVERAL HOURS, AND THEN RECOVERING PURIFIED PHTHALIC ANHYDRIDE BY DISTILLATION.
Claim 2
Independent Claim
99 words
A METHOD OF PURIFYING CRUDE PHTHALIC ANHYDRIDE WHICH COMPRISES PROVIDING A MIXTURE THEREOF WITH FROM ABOUT 0.01% TO BELOW 1%, BY WEIGHT OF SAID ANHYDRIDE, OF AN ALKALI METAL BOROHYDRIDE, AN ALKALINE EARTH METAL BOROHYDRIDE OR A QUATERNARY AMMONIUM BOROHYDRIDE CORRESPONDING TO THE FORMULA (R4)$N WHERE R ARE THE SAME OR DIFFERENT HYDROCARBON RADICALS SELECTED FROM THE GROUP CONSISTING OF METHYL, ETHYL, PROPYL, ISOPROPYL, BUTYL, ISOBUTYL AND CYCLOHEXYL, OR AN ALKALI METAL HYDRIDE OR ALKALINE EARTH METAL HYDRIDE, HEATING SAID MIXTURE AT A TEMPERATURE ABOVE 270 DEGREES C. FOR SEVERAL HOURS, AND THEN RECOVERING PURIFIED PHTHALIC ANHYDRIDE BY DISTILLATION.
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) | 1970-06-26 | 1970-12-26 | 1971-06-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1974-06-26 | 1974-12-26 | 1975-06-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1978-06-26 | 1978-12-26 | 1979-06-27 | $7700.00 | Window Closed / Lapsed |