US4148793A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for the purification of epsilon-caprolactam
Assignee: Bayer AG
•
Filing: 1977-09-09
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Granted: 1979-04-10
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Expires: 1997-09-09
Abstract
Abstract Process for the removal of residues of solvent from crystallized ε-caprolactam, wherein the major quantity of solvent is removed in a first stage by distillation in the presence of water in an amount so that the water content of the residue of the first stage is from 0.5 to 6% by weight, and in a second stage by distilling water and any residues of solvent still present.
Inventors
- 👤 Harry Danziger
- 👤 Ludwig Deibele
- 👤 Bernd-Ulrich Kaiser
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 14:11
CPC Classifications
C; C07; C07D; C07D201/00; C07D201/16
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
137 words
A process for removing solvent present in ε-caprolactam in an amount of 0.1 to 10% by weight which comprises removing solvent from said solvent containing ε-caprolactam in a first stage distillation at a pressure of from 100 to 760 Torr in the presence of about 0.5 to 3 parts by weight of water per part by weight of solvent initially present in said ε-caprolactam until the resulting undistilled ε-caprolactam in the sump has a solvent content of less than 0.1% by weight and a water content of 0.5 to 6% by weight and then subjecting the undistilled ε-caprolactam mixture of said first stage to a second stage water and solvent distillation at a pressure of from 10 to about 100 Torr whereby additional water and solvent are removed, and recovering from the distillation sump pure undistilled ε-caprolactam.
Claim 2
Dependent Claim
137 words
A process for removing solvent present in ε-caprolactam in an amount of 0.1 to 10% by weight which comprises removing solvent from said solvent containing ε-caprolactam in a first stage distillation at a pressure of from 100 to 760 Torr in the presence of about 0.5 to 3 parts by weight of water per part by weight of solvent initially present in said ε-caprolactam until the resulting undistilled ε-caprolactam in the sump has a solvent content of less than 0.1% by weight and a water content of 0.5 to 6% by weight and then subjecting the undistilled ε-caprolactam mixture of said first stage to a second stage water and solvent distillation at a pressure of from 10 to about 100 Torr whereby additional water and solvent are removed, and recovering from the distillation sump pure undistilled ε-caprolactam.
References Cited (Backward Citations)
US2221369A
Cited
US3755305A
Cited
US3794647A
Cited
US3792045A
Cited
US3882102A
Cited
US3944543A
Cited
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 |