US3928579A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for the purification of coal tar
Assignee: Warner Lambert Co LLC
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Filing: 1974-11-25
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Granted: 1975-12-23
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Expires: 1994-11-25
Abstract
Abstract A process is disclosed for the purification of coal tar. This process comprises the extraction of commercially available coal tar with a solvent system boiling at or below 80*C and comprising a fluorocarbon or a hydrocarbon or a mixture of these where the kauri-butanol number of the resulting system has a value of less than 75 and recovering the coal tar extract by filtration and evaporation of the volatile solvent system. The coal tar extract thus obtained is dermatologically more acceptable and clinically more effective than known coal tar extracts or preparations and can be incorporated into many dermatologically acceptable vehicles.
Inventors
- 👤 James Edward Mcshane
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 00:56
CPC Classifications
C; C10; C10C; C10C1/00; C10C1/18; A; A61; A61K; A61K35/00; A61K35/02; A61K35/04
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
74 words
A PROCESS FOR THE PURIFICATION OF COAL TAR WHICH COMPRISES MIXING COAL TAR WITH A NON-POLAR VOLATILE SOLVENT SYSTEM HAVING A KAURI-BUTANOL VALUE OF LESS THAN 75 AND A BOILING POINT NO HIGHER THAN 80*C. COMPRISING A FLUOROCARBON OF THE GROUP CONSISTING OF TRICHLOROFLUOROMETHANE, DICHLORODIFLUOROMETHANE, 1,2-DICHLORO-1,1,2,2-TETRAFLUOROETHANE, 1,1,2-TRICHLORO1,2,2-TRIFLUOROETHANE AND DIFLUOROCHLOROMETHANE, AND MIXTURES THEREOF WITH N-BUTANE, ISOBUTANE, PROPANE, PENTANE AND N-HEXANE, SEPARATING THE SUPERNATANT LIQUID AND EVAPORATING THE SOLVENT TO RECOVER THE DESIRED COAL TAR FRACTION.
Claim 2
Dependent Claim
74 words
A PROCESS FOR THE PURIFICATION OF COAL TAR WHICH COMPRISES MIXING COAL TAR WITH A NON-POLAR VOLATILE SOLVENT SYSTEM HAVING A KAURI-BUTANOL VALUE OF LESS THAN 75 AND A BOILING POINT NO HIGHER THAN 80*C. COMPRISING A FLUOROCARBON OF THE GROUP CONSISTING OF TRICHLOROFLUOROMETHANE, DICHLORODIFLUOROMETHANE, 1,2-DICHLORO-1,1,2,2-TETRAFLUOROETHANE, 1,1,2-TRICHLORO1,2,2-TRIFLUOROETHANE AND DIFLUOROCHLOROMETHANE, AND MIXTURES THEREOF WITH N-BUTANE, ISOBUTANE, PROPANE, PENTANE AND N-HEXANE, SEPARATING THE SUPERNATANT LIQUID AND EVAPORATING THE SOLVENT TO RECOVER THE DESIRED COAL TAR FRACTION.
References Cited (Backward Citations)
US2000117A
Cited
US3071510A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-12-22 | 1979-06-23 | 1979-12-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-12-22 | 1983-06-23 | 1983-12-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-12-22 | 1987-06-23 | 1987-12-23 | $7700.00 | Window Closed / Lapsed |