Patent US3734941A successfully refreshed from Google Patents.
US3734941A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for converting urethanes to isocyanates
Assignee: Wyeth Holdings LLC
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Filing: 1968-09-06
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Granted: 1973-05-22
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Expires: 1988-09-06
Abstract
Abstract A PROCESS FOR PRODUCING ISOCYANATES FROM URETHANES WHICH COMPRISES HEATING A URETHANE OF THE FORMULA: R(NHCOOR'')X WHEREIN R IS ALKYL OF FROM 1 TO 18 CARBON ATOMS, ARYL OR ALKARYL CONTAINING LESS THAN 3 RINGS, R'' IS ALKYL OF 1 TO 6 CARBON ATOMS, ARYL OR ALKARYL OF LESS THAN THREE RINGS, AND X IS 1, 2 OR 3, AT A TEMPERATURE BETWEEN 400*C. AND 600*C. IN THE PRESENCE OF A LEWIS ACID TO FORM VAPORS AND CONDENSING THE VAPORS TO RECOVER AN ORGANIC ISOCYANATE.
Inventors
- 👤 W Sydor
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 19:43
CPC Classifications
C; C07; C07C; C07C263/00; C07C263/04; C07C319/00; C07C319/14; C07C319/20
Claims Analysis
Total Claims: 0
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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) | 1976-05-21 | 1976-11-20 | 1977-05-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-05-21 | 1980-11-20 | 1981-05-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-05-21 | 1984-11-20 | 1985-05-22 | $7700.00 | Window Closed / Lapsed |