Patent US2738352A successfully refreshed from Google Patents.
US2738352A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Purification of pyridine compounds
Assignee: —
•
Filing: —
•
Granted: 1956-03-13
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Expires: 1973-03-13
Abstract
No abstract record available.
Inventors
No inventors recorded.
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 14:36
CPC Classifications
C; C07; C07D; C07D213/00; C07D213/02; C07D213/04; C07D213/60; C07D213/62; C07D213/69
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
56 words
A PROCESS FOR THE PURIFICATION OF CITRAZINIC ACID WHICH COMPRISES CONTACTING CRUDE CITRAZINIC ACID WITH STRONG SULFURIC ACID, HAVING A CONCENTRATION OF FROM ABOUT 65 TO ABOUT 80% BY WEIGHT, AT AN ELEVATED TEMPERATURE, REMOVING THE CRYSTALLINE SOLID THAT FORMS UPON COOLING THE MIXTURE AND CONTACTING SAID CRYSTALLINE SOLID WITH WATER TO FORM PURIFIED CITRAZINIC ACID.
Claim 2
Dependent Claim
56 words
A PROCESS FOR THE PURIFICATION OF CITRAZINIC ACID WHICH COMPRISES CONTACTING CRUDE CITRAZINIC ACID WITH STRONG SULFURIC ACID, HAVING A CONCENTRATION OF FROM ABOUT 65 TO ABOUT 80% BY WEIGHT, AT AN ELEVATED TEMPERATURE, REMOVING THE CRYSTALLINE SOLID THAT FORMS UPON COOLING THE MIXTURE AND CONTACTING SAID CRYSTALLINE SOLID WITH WATER TO FORM PURIFIED CITRAZINIC ACID.
References Cited (Backward Citations)
GB619241A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1959-03-13 | 1959-09-12 | 1960-03-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1963-03-13 | 1963-09-12 | 1964-03-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1967-03-13 | 1967-09-12 | 1968-03-13 | $7700.00 | Window Closed / Lapsed |