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US4822947A
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Separation of m-xylene from o-xylene by extractive distillation with DMSO
Assignee: Individual
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Filing: 1987-06-15
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Granted: 1989-04-18
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Expires: 2007-06-15
Abstract
Abstract m-Xylene is difficult to separate from o-xylene by conventional distillation or rectification because of the close proximity of their boiling points. m-Xylene can be readily separated from o-xylene by using extractive distillation in which the extractive agent is dimethylsulfoxide or a mixture of it with certain high boiling organic compounds. Typical examples of effective agents are: dimethylsulfoxide; dimethylsulfoxide and 1,4-butanediol; dimethylsulfoxide, nitrobenzene and diethylene glycol.
Inventors
- 👤 Lloyd Berg
- 👤 An-I Yeh
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 14:59
CPC Classifications
C; C07; C07C; C07C7/00; C07C7/04; C07C7/05; C07C7/08
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
103 words
A method for recovering m-xylene from a mixture of m-xylene and o-xylene which comprises distilling a mixture of m-xylene and o-xylene in a rectification column in the presence of about one part of extractive agent per part of m-xylene--o-xylene mixture, recovering m-xylene as overhead product and obtaining the extractive agent and o-xylene from the stillpot, the extractive agent contains dimethylsulfoxide and at least one material selected from the group consisting of benzonitrile, phthalic anhydride, 1,4,-butanediol, hydroquinone, catechol, bis-phenol A, n-octanol, ethylene glycolphenyl ether, diisodecyl phthalate, methyl salicylate, glycerine, ethyl acetoacetate, 1,5-pentanediol, dipropylene glycol, dimethylformide, propyl p-hydroxybenzoate, ethyl salicylate, ethylene carbonate and propylene carbonate.
Claim 2
Independent Claim
103 words
A method for recovering m-xylene from a mixture of m-xylene and o-xylene which comprises distilling a mixture of m-xylene and o-xylene in a rectification column in the presence of about one part of extractive agent per part of m-xylene--o-xylene mixture, recovering m-xylene as overhead product and obtaining the extractive agent and o-xylene from the stillpot, the extractive agent contains dimethylsulfoxide and at least one material selected from the group consisting of benzonitrile, phthalic anhydride, 1,4,-butanediol, hydroquinone, catechol, bis-phenol A, n-octanol, ethylene glycolphenyl ether, diisodecyl phthalate, methyl salicylate, glycerine, ethyl acetoacetate, 1,5-pentanediol, dipropylene glycol, dimethylformide, propyl p-hydroxybenzoate, ethyl salicylate, ethylene carbonate and propylene carbonate.
References Cited (Backward Citations)
US4488937A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-04-17 | 1992-10-17 | 1993-04-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-04-17 | 1996-10-17 | 1997-04-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-04-17 | 2000-10-17 | 2001-04-18 | $7700.00 | Window Closed / Lapsed |