US3755305A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for the purification of caprolactam
Assignee: Bayer AG
•
Filing: 1971-04-15
•
Granted: 1973-08-28
•
Expires: 1991-04-15
Abstract
Abstract The invention relates to a process for the purification of Epsilon -caprolactam prepared by catalytic cyclohexanone oxime rearrangement in the gaseous phase which comprises mixing the crude lactam at a temperature above its melting point with at least one branched aliphatic hydrocarbon, the mixing proportions ensuring the formation of a liquid lactam phase in addition to the hydrocarbon phase, separating off the hydrocarbon phase, recrystallising the dissolved lactam from the hydrocarbon phase by cooling, and subjecting the lactam crystals thus obtained to fractional vacuum distillation.
Inventors
- 👤 H Schwarz
- 👤 O Immel
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 12:01
CPC Classifications
C; C07; C07D; C07D201/00; C07D201/16
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
12 words
A process as claimed in claim 1, wherein the hydrocarbon is trimethylpentane.
Claim 2
Dependent Claim
12 words
A process as claimed in claim 1, wherein the hydrocarbon is isododecane.
Claim 3
Dependent Claim
26 words
A process as claimed in any of claims 1 to 3, wherein the crude lactam is mixed with the hydrocarbon at a temperature above 65* C.
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) | 1976-08-27 | 1977-02-26 | 1977-08-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-08-27 | 1981-02-26 | 1981-08-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-08-27 | 1985-02-26 | 1985-08-28 | $7700.00 | Window Closed / Lapsed |