US3540987A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Purification of phthalic anhydride by batch distillation,accumulation and continuous distillation
Assignee: GEA Group AG
•
Filing: 1968-05-22
•
Granted: 1970-11-17
•
Expires: 1988-05-22
Abstract
No abstract record available.
Inventors
- 👤 Otto Garkisch
- 👤 Wolf Mehner
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 04:08
CPC Classifications
C; C07; C07C; C07C51/00; C07C51/54; C07C51/573; Y; Y10; Y10S; Y10S203/00; Y10S203/13; Y10S203/20
Claims Analysis
Total Claims: 0
No claims parsed yet. Click Sync Now above to re-index claims from Google Patents.
References Cited (Backward Citations)
US3178452A
Cited
US2405393A
Cited
US2526710A
Cited
US2670325A
Cited
US2995500A
Cited
US2786805A
Cited
US2965549A
Cited
US3011955A
Cited
US3280009A
Cited
US3187016A
Cited
DE1227443B
Cited
US3380896A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1973-11-16 | 1974-05-18 | 1974-11-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1977-11-16 | 1978-05-18 | 1978-11-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1981-11-16 | 1982-05-18 | 1982-11-17 | $7700.00 | Window Closed / Lapsed |