Patent US4148792A successfully refreshed from Google Patents.
US4148792A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Purification of caprolactam
Assignee: Bayer AG
•
Filing: 1978-06-15
•
Granted: 1979-04-10
•
Expires: 1998-06-15
Abstract
Abstract A process for the purification of ε-caprolactam, wherein ε-caprolactam is treated with potassium permanganate in the presence of from 0.01 to 5% by weight of water, based on caprolactam, and subsequently crystallized from toluene, benzene, ethylbenzene or xylene.
Inventors
- 👤 Harry Danziger
- 👤 Otto Immel
- 👤 Bernd-Ulrich Kaiser
- 👤 Guido Rampart
- 👤 Hans-Helmut Schwarz
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 15:06
CPC Classifications
C; C07; C07D; C07D201/00; C07D201/16
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
58 words
A process for the purification of ε-caprolactam obtained from crude caprolactam of the gaseous-phase rearrangement of cyclohexanone oxime or produced by Beckmann's rearrangement which comprises treating said crude caprolactam with potassium permanganate in the presence of from 0.01 to 5% by weight of water, based on the ε-caprolactam, and subsequently crystallizing ε-caprolactam from toluene, benzene, ethylbenzene or xylene.
Claim 2
Dependent Claim
58 words
A process for the purification of ε-caprolactam obtained from crude caprolactam of the gaseous-phase rearrangement of cyclohexanone oxime or produced by Beckmann's rearrangement which comprises treating said crude caprolactam with potassium permanganate in the presence of from 0.01 to 5% by weight of water, based on the ε-caprolactam, and subsequently crystallizing ε-caprolactam from toluene, benzene, ethylbenzene or xylene.
Claim 3
Dependent Claim
14 words
A process as claimed in claim 1, wherein the ε-caprolactam is crystallised from toluene.
Claim 4
Dependent Claim
22 words
A process as claimed in claim 1, wherein from 0.05 to 0.1% by weight of water, based on the ε-caprolactam is present.
Claim 5
Dependent Claim
32 words
A process as claimed in any of claim 1, wherein the quantity of potassium permanganate is controlled so that it is completely reduced in 5 minutes at a temperature of 80° 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) | 1982-04-09 | 1982-10-09 | 1983-04-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-04-09 | 1986-10-09 | 1987-04-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-04-09 | 1990-10-09 | 1991-04-10 | $7700.00 | Window Closed / Lapsed |