US2663731A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Purification of urea
Assignee: BASF SE
•
Filing: 1951-03-26
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Granted: 1953-12-22
•
Expires: 1971-03-26
Abstract
No abstract record available.
Inventors
- 👤 Michelitsch Walter
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 14:15
CPC Classifications
C; C07; C07C; C07C273/00; C07C273/02; C07C273/14; C07C273/16
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
46 words
A PROCESS FOR PURIFYING SOLID UREA CONTAINING BIURET AS AN IMPURITY WHICH COMPRISES TREAT ING A SOLID BIURET-CONTAINING UREA WITH AN AQUEOUS SOLUTION OF UREA, THEREBY TO DISSOLVE OUT THE BIURET WHILE LEAVING THE UREA SUBSTANTIALLY UNDISSOLVED, AND SEPARATING THE PURIFIED SOLID UREA FROM THE SOLUTION.
Claim 2
Dependent Claim
46 words
A PROCESS FOR PURIFYING SOLID UREA CONTAINING BIURET AS AN IMPURITY WHICH COMPRISES TREAT ING A SOLID BIURET-CONTAINING UREA WITH AN AQUEOUS SOLUTION OF UREA, THEREBY TO DISSOLVE OUT THE BIURET WHILE LEAVING THE UREA SUBSTANTIALLY UNDISSOLVED, AND SEPARATING THE PURIFIED SOLID UREA FROM THE SOLUTION.
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) | 1956-12-21 | 1957-06-22 | 1957-12-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1960-12-21 | 1961-06-22 | 1961-12-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1964-12-21 | 1965-06-22 | 1965-12-22 | $7700.00 | Window Closed / Lapsed |