US4892624A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Workup of distillation residues from the purification of caprolactam
Assignee: BASF SE
•
Filing: 1988-08-25
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Granted: 1990-01-09
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Expires: 2008-08-25
Abstract
Abstract Distillation residues from the purification of caprolactam are worked up by heating in the presence of sodium hydroxide or potassium hydroxide and in the presence of a high-boiling hydrocarbon at from 250° to 500° C. and continuously removing the caprolactam.
Inventors
- 👤 Hugo Fuchs
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 17:56
CPC Classifications
C; C07; C07D; C07D201/00; C07D201/16
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
104 words
A process for the recovery of caprolactam from a distillation residue containing caprolactam, oligomers of caprolactam, polymers of caprolactam and unidentified decomposition and reaction products, which process comprises (a) adding to said distillation residue sodium or potassium hydroxide and per part by weight of distillation residue from 0.1 to 10 parts by weight of high boiling hydrocarbons having a boiling point above 250° C. up to 450° C., (b) heating the mixture of said distillation residue, sodium hydroxide or potassium hydroxide, and high boiling hydrocarbons to a temperature of from 250° to 450° C., and (c) removing continuously vaporized caprolactam from said heated mixture.
Claim 2
Dependent Claim
104 words
A process for the recovery of caprolactam from a distillation residue containing caprolactam, oligomers of caprolactam, polymers of caprolactam and unidentified decomposition and reaction products, which process comprises (a) adding to said distillation residue sodium or potassium hydroxide and per part by weight of distillation residue from 0.1 to 10 parts by weight of high boiling hydrocarbons having a boiling point above 250° C. up to 450° C., (b) heating the mixture of said distillation residue, sodium hydroxide or potassium hydroxide, and high boiling hydrocarbons to a temperature of from 250° to 450° C., and (c) removing continuously vaporized caprolactam from said heated mixture.
Claim 3
Dependent Claim
26 words
The process of claim 1 wherein a high boiling hydrocarbon having a boiling point of from 350° C. to 450° C. is used in step a.
Claim 4
Dependent Claim
19 words
The process of claim 1, wherein a temperature of from 280° to 380° C. is maintained on step b.
Claim 5
Dependent Claim
13 words
The process of claim 1, wherein reduced pressure is employed in step C.
Claim 6
Dependent Claim
32 words
The process of claim 1, wherein the vaporized caprolactam is continuously removed by passing an inert gas through the mixture of distillation residue, sodium hydroxide or potassium hydroxide, and high boiling hydrocarbons.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-01-08 | 1993-07-10 | 1994-01-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-01-08 | 1997-07-10 | 1998-01-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-01-08 | 2001-07-10 | 2002-01-09 | $7700.00 | Window Closed / Lapsed |