Patent US2900480A successfully refreshed from Google Patents.
Patent US3947751A successfully refreshed from Google Patents.
US3882102A
Expired / Lapsed
US
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Process for the purification of caprolactam
Assignee: Bayer AG
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Filing: 1973-10-24
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Granted: 1975-05-06
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Expires: 1993-10-24
Abstract
Abstract The invention relates to a process for the purification of caprolactam which is obtained by rearrangement of cyclohexanone oxime in the gas phase in the presence of solid catalysts. The purification takes place by dissolving the crude lactam in benzene or in alkyl benzene with seven to eight carbon atoms and recrystallization whilst cooling.
Inventors
- 👤 Otto Immel
- 👤 Hans-Helmut Schwarz
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 16:49
CPC Classifications
C; C07; C07D; C07D201/00; C07D201/16
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
85 words
A PROCESS FOR THE TREATMENT OF THE CRUDE PRODUCT RESULTING FROM THE CATALYTIC REARRANGEMENT OF CYCLOHEXANONE OXIME, IN THE GAS PHASE, TO $-CAPROLACTAM IN THE PRESENCE OF A BORON TRIOXIDE-CONTAINING CATALYST WHICH COMPRISES THE STEPS OF: A. DISSOLVING SAID CRUDE PRODUCE IN BENZENE OR AN ALKYL BENZENE HAVING SEVEN TO EIGHT CARBON ATOMS; B. STIRRING AND COOLING SAID SOLUTION AND PRECIPITTING $CAPROLACTAM AT ABOUT 0* TO 50*C; C. FILTERING THE RESULTANT CRYSTAL SLUDGE FROM SAID SOLUTION; AND D. RECOVERING SUBSTANTIALLY PURE $-CAPROLACTAM BY VACUUM DISTILLATION.
Claim 2
Dependent Claim
85 words
A PROCESS FOR THE TREATMENT OF THE CRUDE PRODUCT RESULTING FROM THE CATALYTIC REARRANGEMENT OF CYCLOHEXANONE OXIME, IN THE GAS PHASE, TO $-CAPROLACTAM IN THE PRESENCE OF A BORON TRIOXIDE-CONTAINING CATALYST WHICH COMPRISES THE STEPS OF: A. DISSOLVING SAID CRUDE PRODUCE IN BENZENE OR AN ALKYL BENZENE HAVING SEVEN TO EIGHT CARBON ATOMS; B. STIRRING AND COOLING SAID SOLUTION AND PRECIPITTING $CAPROLACTAM AT ABOUT 0* TO 50*C; C. FILTERING THE RESULTANT CRYSTAL SLUDGE FROM SAID SOLUTION; AND D. RECOVERING SUBSTANTIALLY PURE $-CAPROLACTAM BY VACUUM DISTILLATION.
Claim 3
Dependent Claim
14 words
The process of claim 1 in which said crude product is dissolved in toluene.
Claim 4
Dependent Claim
14 words
The process of claim 1 in which said crude product is dissolved in xylene.
Claim 5
Dependent Claim
45 words
In the process of purifying crude epsilon -caprolactam prepared by the rearrangement of cyclohexanone oxime in the gas phase in the presence of solid catalyst; the improvement comprising recrystallizing the crude epsilon -caprolactam in benzene or an alkyl benzene having seven to eight carbon atoms.
Claim 6
Dependent Claim
45 words
In the process of purifying crude epsilon -caprolactam prepared by the rearrangement of cyclohexanone oxime in the gas phase in the presence of solid catalyst; the improvement comprising recrystallizing the crude epsilon -caprolactam in benzene or an alkyl benzene having seven to eight carbon atoms.
References Cited (Backward Citations)
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US3145198A
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US2313026A
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US3359260A
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US3485820A
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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) | 1978-05-05 | 1978-11-04 | 1979-05-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-05-05 | 1982-11-04 | 1983-05-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-05-05 | 1986-11-04 | 1987-05-06 | $7700.00 | Window Closed / Lapsed |