US2662901A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for purifying phthalic anhydride
Assignee: Honeywell International Inc
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Filing: 1949-03-11
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Granted: 1953-12-15
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Expires: 1969-03-11
Abstract
No abstract record available.
Inventors
- 👤 Maurice E Bailey
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 18:42
CPC Classifications
C; C07; C07C; C07C51/00; C07C51/54; C07C51/573
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
67 words
A PROCESS FOR THE PURIFICATION OF CRUDE PHTHALIC ANHYDRIDE OBTAINED BY CATALYTIC OXIDATION OF NAPHTHALENE VAPORS AND CONTAINING NAPHTHOQUINONE TYPE IMPURITIES, WHICH COMPRISES HEATING THE CRUDE PHTHALIC ANHYDRIDE IN THE MOLTEN PHASE IN THE PRESENCE OF A SMALL QUANTITY OF AN ALKALI METAL SALT OF THE GROUP CONSISTING OF SODIUM AND POTASSIUM BISULFITES, META BISULFITES, HYDROSULFITES AND SULFOXYLATES, AND THEREAFTER RECOVERING THE PURIFIED PHTHALIC ANHYDRIDE BY VOLATILIZATION.
Claim 2
Dependent Claim
67 words
A PROCESS FOR THE PURIFICATION OF CRUDE PHTHALIC ANHYDRIDE OBTAINED BY CATALYTIC OXIDATION OF NAPHTHALENE VAPORS AND CONTAINING NAPHTHOQUINONE TYPE IMPURITIES, WHICH COMPRISES HEATING THE CRUDE PHTHALIC ANHYDRIDE IN THE MOLTEN PHASE IN THE PRESENCE OF A SMALL QUANTITY OF AN ALKALI METAL SALT OF THE GROUP CONSISTING OF SODIUM AND POTASSIUM BISULFITES, META BISULFITES, HYDROSULFITES AND SULFOXYLATES, AND THEREAFTER RECOVERING THE PURIFIED PHTHALIC ANHYDRIDE BY VOLATILIZATION.
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) | 1956-12-14 | 1957-06-15 | 1957-12-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1960-12-14 | 1961-06-15 | 1961-12-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1964-12-14 | 1965-06-15 | 1965-12-15 | $7700.00 | Window Closed / Lapsed |