US3944543A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for recovery of ε-caprolactam
Assignee: Stamicarbon BV
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Filing: 1974-06-11
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Granted: 1976-03-16
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Expires: 1994-06-11
Abstract
Abstract Polymerizable quality ε-caprolactam having an alkalinity of less than 0.05 meq. per kg. of lactam is produced in the improved disclosed process which includes extracting an aqueous lactam-rich solution with an organic solvent having a high distribution coefficient for the lactam with respect to the aqueous solution, and evaporating the lactam-rich organic solvent solution and recovering by distillation the lactam. Evaporation of the organic solvent requires considerably less thermal energy than evaporation of a similar aqueous solution.
Inventors
- 👤 Reijer Goettsch
- 👤 Abraham H. de Rooij
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 23:21
CPC Classifications
C; C07; C07D; C07D201/00; C07D201/16
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
144 words
In a process for the purification and recovery of ε-caprolactam monomer of reduced alkalinity content including the steps of neutralizing a rearrangement mixture of the lactam and sulfuric acid to form an aqueous solution of lactam and ammonium hydrogen sulfate, extracting the lactam from the mixture with a water-immiscible organic solvent for the lactam, extracting the lactam/organic solvent solution with water to form an aqueous solution of lactam, the improvement comprising extracting the thus-obtained aqueous lactam-rich solution with a water-immiscible organic solvent having a high distribution coefficient for the lactam with respect to the water of the aqueous solution forming a solution of the lactam in the organic solvent and thereafter evaporating the lactam-rich organic solvent and thereby recovering the purified lactam from the evaporation of the organic solvent, the thus-recovered lactam having an alkalinity of less than 0.05 meq. per kg of lactam.
Claim 2
Dependent Claim
144 words
In a process for the purification and recovery of ε-caprolactam monomer of reduced alkalinity content including the steps of neutralizing a rearrangement mixture of the lactam and sulfuric acid to form an aqueous solution of lactam and ammonium hydrogen sulfate, extracting the lactam from the mixture with a water-immiscible organic solvent for the lactam, extracting the lactam/organic solvent solution with water to form an aqueous solution of lactam, the improvement comprising extracting the thus-obtained aqueous lactam-rich solution with a water-immiscible organic solvent having a high distribution coefficient for the lactam with respect to the water of the aqueous solution forming a solution of the lactam in the organic solvent and thereafter evaporating the lactam-rich organic solvent and thereby recovering the purified lactam from the evaporation of the organic solvent, the thus-recovered lactam having an alkalinity of less than 0.05 meq. per kg of lactam.
Claim 3
Dependent Claim
17 words
The process according to claim 1 wherein the solvents used in both extraction steps are the same.
Claim 4
Dependent Claim
28 words
The process according to claim 1 wherein the extraction solvent of step (1) is a chlorinated hydrocarbon selected from the group consisting of chloroform, methylene chloride and 1,2-dichloroethane.
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) | 1979-03-16 | 1979-09-15 | 1980-03-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-03-16 | 1983-09-15 | 1984-03-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-03-16 | 1987-09-15 | 1988-03-16 | $7700.00 | Window Closed / Lapsed |