US4523041A
Expired / Lapsed
US
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Method of purifying 4-fluorophenol
Assignee: Central Glass Co Ltd
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Filing: 1984-05-25
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Granted: 1985-06-11
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Expires: 2004-05-25
Abstract
Abstract A method of efficiently purifying crude 4-fluorophenol containing phenol as impurity. Phthalic acid or its anhydride, or a suitable derivative of phthalic acid, and a dehydrating agent such as sulfuric acid or a metal chloride are mixed with the crude 4-fluorophenol, and the mixture is kept in a liquid state usually with moderate heating to 30°-180° C. until completion of condensation reaction between phenol and the phthal-compound. After that pure 4-fluorophenol can easily be recovered by distillation or recrystallization.
Inventors
- 👤 Toshikazu Kawai
- 👤 Haruo Suzuki
- 👤 Shouzou Kaneda
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 19:41
CPC Classifications
C; C07; C07C; C07C37/00; C07C37/68; C07C37/86
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
72 words
A method of purifying crude 4-fluorophenol containing phenol as impurity, the method comprising the steps of: adding a phthal-compound which readily reacts with phenol but hardly reacts with 4-fluorophenol and a dehydrating agent to the crude 4-fluorophenol to obtain a mixture; keeping said mixture in a liquid state until substantial completion of the reaction between said phenol and said phthal-compound; and recovering 4-fluorophenol from the mixture containing the products of said reaction.
Claim 2
Independent Claim
72 words
A method of purifying crude 4-fluorophenol containing phenol as impurity, the method comprising the steps of: adding a phthal-compound which readily reacts with phenol but hardly reacts with 4-fluorophenol and a dehydrating agent to the crude 4-fluorophenol to obtain a mixture; keeping said mixture in a liquid state until substantial completion of the reaction between said phenol and said phthal-compound; and recovering 4-fluorophenol from the mixture containing the products of said reaction.
Claim 3
Dependent Claim
31 words
A method according to claim 1, wherein said phthal-compound is selected from the group consisting of phthalic acid, chlorophthalic acid, fluorophthalic acid, methylphthalic acid, nitrophthalic acid, o-sulfobenzoic acid and their anhydrides.
Claim 4
Dependent Claim
23 words
A method according to claim 2, wherein the amount of said phthal-compound is at least 0.5 mole per 1 mole of said phenol.
Claim 5
Dependent Claim
36 words
A method according to claim 3, wherein said dehydrating agent is selected from the group consisting of sulfuric acid, zinc chloride, zinc bromide, aluminum chloride, iron chloride, tin chloride, phosphorus pentoxide, polyphosphoric acid and toluenesulfonic acid.
Claim 6
Dependent Claim
18 words
A method according to claim 4, wherein said dehydrating agent amounts to 10-200% by weight of said phthal-compound.
Claim 7
Dependent Claim
27 words
A method according to claim 1, wherein said mixture is kept heated at temperatures in the range from 30° to 180° C. until completion of said reaction.
Claim 8
Dependent Claim
20 words
A method according to claim 1, wherein an unreactive organic solvent is added to said mixture in the initial step.
References Cited (Backward Citations)
US2934569A
Cited
US2950325A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1988-06-10 | 1988-12-10 | 1989-06-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-06-10 | 1992-12-10 | 1993-06-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-06-10 | 1996-12-10 | 1997-06-11 | $7700.00 | Window Closed / Lapsed |