US4139562A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for purifying crude p-aminophenol
Assignee: Mitsui Toatsu Chemicals Inc
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Filing: 1978-03-13
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Granted: 1979-02-13
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Expires: 1998-03-13
Abstract
Abstract A process for purifying crude p-aminophenol which contains 4,4'-diaminodiphenyl ether and other impurities, which process comprising adding an alkali metal compound to the crude p-aminophenol in an aqueous medium in an atmosphere of an inert gas and, if necessary, in the presence of a reducing agent to give an aqueous solution of an alkali metal salt of p-aminophenol, and contacting the aqueous solution with an inert organic solvent immiscible with water to permit 4,4'-diaminodiphenyl ether and other impurities to be separated by extraction in the solvent.
Inventors
- 👤 Ryuichi Yamamoto
- 👤 Yutaka Hirai
- 👤 Teruyuki Nagata
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 03:27
CPC Classifications
A; A01; A01N; A01N43/00; A01N43/90; C; C07; C07C; C07C215/00; C07C215/74; C07C215/76
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
71 words
A process for the purification of crude p-aminophenol, including contacting the crude p-aminophenol with a solvent to extract impurities contained in the crude p-aminophenol, characterized by forming an aqueous alkali metal salt solution of the crude p-aminophenol in an atmosphere of an inert gas, and contacting said salt solution with an inactive organic solvent immiscible with water to permit the impurities to be separated therefrom in the inactive solvent by extraction.
Claim 2
Dependent Claim
71 words
A process for the purification of crude p-aminophenol, including contacting the crude p-aminophenol with a solvent to extract impurities contained in the crude p-aminophenol, characterized by forming an aqueous alkali metal salt solution of the crude p-aminophenol in an atmosphere of an inert gas, and contacting said salt solution with an inactive organic solvent immiscible with water to permit the impurities to be separated therefrom in the inactive solvent by extraction.
Claim 3
Dependent Claim
24 words
The process according to claim 1, wherein the crude p-aminophenol is obtained by the catalytic hydrogenation of nitrobenzene in an aqueous sulfuric acid medium.
Claim 4
Dependent Claim
21 words
The process according to claim 1, wherein said salt solution forming step is conducted in the presence of a reducing agent.
Claim 5
Dependent Claim
15 words
The process according to claim 1, wherein said inactive organic solvent is an aromatic amine.
Claim 6
Dependent Claim
16 words
The process according to claim 1, wherein said alkali metal salt is sodium or potassium salt.
Claim 7
Dependent Claim
17 words
The process according to claim 3, wherein said reducing agent is anhydrous sodium dithionite and/or sodium sulfite.
Claim 8
Dependent Claim
12 words
The process according to claim 4, wherein said aromatic amine is aniline.
Claim 9
Dependent Claim
77 words
The process according to claim 2, wherein an alkali is mixed with an aqueous crude p-aminophenol solution obtained by the catalytic hydrogenation of nitrobenzene in an aqueous sulfuric acid medium to adjust the pH of the solution to 7 to 8 and to precipitate crude p-aminophenol therefrom, the resulting precipitate being separated from an aqueous phase and dissolved in an aqueous alkali metal solution, thereby to form the aqueous alkali metal salt solution of the crude p-aminophenol.
Claim 10
Dependent Claim
25 words
The process according to claim 8, wherein the concentration of said alkali in the aqueous alkali metal solution is from 5 to 15 weight %.
Claim 11
Dependent Claim
21 words
The process according to claim 8, wherein said alkali mixed with said aqueous crude p-aminophenol solution is an aqueous ammonia solution.
References Cited (Backward Citations)
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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) | 1982-02-12 | 1982-08-14 | 1983-02-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-02-12 | 1986-08-14 | 1987-02-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-02-12 | 1990-08-14 | 1991-02-13 | $7700.00 | Window Closed / Lapsed |