US4256669A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Para-aminophenol derivatives
Assignee: Mallinckrodt Chemical Inc
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Filing: 1978-11-08
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Granted: 1981-03-17
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Expires: 1998-11-08
Abstract
Abstract A process for the preparation of diaryl para-phenylenediamines from a crude para-aminophenol solution such as obtained by the catalytic hydrogenation of nitrobenzene in an aqueous acid reaction medium. The process comprises contacting the para-aminophenol containing acidic solution, after neutralization with ammonia, with an aromatic amine selected from the group consisting of aniline, mixed toluidines, ortho-toluidine, mixed xylidines, and mixtures thereof under conditions whereby the aromatic amine extracts the para-aminophenol from the crude feed solution and is separated therefrom. The separated solution comprised essentially of the aromatic amine extractant, para-aminophenol, and minor amounts of impurities is then contacted with an alkylation catalyst to produce the diaryl para-phenylenediamines.
Inventors
- 👤 Roland G. Benner
- 👤 Paul D. Henson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 19:12
CPC Classifications
C; C07; C07C; C07C213/00; C07C213/10
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
60 words
A method for extracting para-aminophenol with aromatic amines from a crude aqueous solution of para-aminophenol made by the reduction of nitrobenzene, which comprises contacting the crude aqueous solution with at least a sufficient amount of an aromatic amine to extract the crude para-aminophenol therefrom, and then contacting the resulting extract with a condensation catalyst to form the corresponding diaryl para-phenylenediamines.
Claim 2
Independent Claim
60 words
A method for extracting para-aminophenol with aromatic amines from a crude aqueous solution of para-aminophenol made by the reduction of nitrobenzene, which comprises contacting the crude aqueous solution with at least a sufficient amount of an aromatic amine to extract the crude para-aminophenol therefrom, and then contacting the resulting extract with a condensation catalyst to form the corresponding diaryl para-phenylenediamines.
Claim 3
Dependent Claim
37 words
The method of claim 1 wherein the pH of the crude aqueous solution is initially adjusted to a pH of 6.6 to 9.0 and then heated to a temperature within the range of 50° to 100° C.
Claim 4
Dependent Claim
33 words
The method of claim 1 wherein the para-aminophenol is extracted with an aromatic amine in a mol ratio of from about 2 to 9 mols of the aromatic amine per mol of para-aminophenol.
Claim 5
Dependent Claim
25 words
The method of claim 1 wherein the resulting extract is contacted with the condensation catalyst at a temperature of from about 100° to 325° C.
Claim 6
Dependent Claim
23 words
The method of claim 1 wherein the crude aqueous acidic solution is prepared by the catalytic hydrogenation of nitrobenzene in aqueous sulfuric acid.
Claim 7
Dependent Claim
25 words
The method of claim 1 wherein the aromatic amine is selected from the group consisting of aniline, mixed toluidines, mixed xylidines, ortho-toluidine, or mixtures thereof.
Claim 8
Dependent Claim
11 words
The method of claim 1 wherein the aromatic amine is aniline.
Claim 9
Dependent Claim
12 words
The method of claim 1 wherein the aromatic amine is mixed xylidines.
Claim 10
Dependent Claim
12 words
The method of claim 1 wherein the aromatic amine is mixed toluidines.
Claim 11
Dependent Claim
20 words
The method of claim 1 wherein the extraction is carried out so that there are at least 3 transfer units.
Claim 12
Dependent Claim
12 words
The method of claim 1 wherein the condensation catalyst is ferric chloride.
Claim 13
Dependent Claim
12 words
The method of claim 1 wherein the condensation catalyst is sulfanilic acid.
Claim 14
Independent Claim
144 words
A method for the preparation of diaryl para-phenylenediamines from a crude neutralized aqueous feed solution containing para-aminophenol which comprises the following sequential steps: (a) extracting the para-aminophenol from the crude aqueous feed solution, maintained at a temperature of from about 50° to 100° C., by contacting it with an aromatic amine selected from the group consisting of aniline, mixed toluidines, mixed xylidines, ortho-toluidine, and mixtures thereof, the amount of aromatic amine ranging from about 2 to 9 mols per mols of para-aminophenol; (b) recovering an extract solution comprising said para-aminophenol and said aromatic amine; (c) passing said extract solution to a reaction zone where it contacts a condensation catalyst at a temperature of from about 100° to 325° C. whereby the para-aminophenol and the aromatic amine react and form corresponding diaryl para-phenylenediamines; and (d) recovering the diaryl para-phenylenediamines from the resulting reaction product mixture.
Claim 15
Independent Claim
144 words
A method for the preparation of diaryl para-phenylenediamines from a crude neutralized aqueous feed solution containing para-aminophenol which comprises the following sequential steps: (a) extracting the para-aminophenol from the crude aqueous feed solution, maintained at a temperature of from about 50° to 100° C., by contacting it with an aromatic amine selected from the group consisting of aniline, mixed toluidines, mixed xylidines, ortho-toluidine, and mixtures thereof, the amount of aromatic amine ranging from about 2 to 9 mols per mols of para-aminophenol; (b) recovering an extract solution comprising said para-aminophenol and said aromatic amine; (c) passing said extract solution to a reaction zone where it contacts a condensation catalyst at a temperature of from about 100° to 325° C. whereby the para-aminophenol and the aromatic amine react and form corresponding diaryl para-phenylenediamines; and (d) recovering the diaryl para-phenylenediamines from the resulting reaction product mixture.
Claim 16
Dependent Claim
19 words
The method of claim 13 wherein the pH of the crude feed solution ranges from about 7.0 to 7.4.
Claim 17
Dependent Claim
22 words
The method of claim 13 wherein the crude feed solution is obtained from the catalytic hydrogenation of nitrobenzene in aqueous sulfuric acid.
Claim 18
Dependent Claim
11 words
The method of claim 13 wherein the aromatic amine is aniline.
Claim 19
Dependent Claim
12 words
The method of claim 13 wherein the aromatic amine is mixed xylidines.
Claim 20
Dependent Claim
12 words
The method of claim 13 wherein the aromatic amine is mixed toluidines.
Claim 21
Dependent Claim
20 words
The method of claim 13 wherein the extraction is carried out so that there are at least 3 transfer units.
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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) | 1984-03-16 | 1984-09-15 | 1985-03-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-03-16 | 1988-09-15 | 1989-03-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-03-16 | 1992-09-15 | 1993-03-17 | $7700.00 | Window Closed / Lapsed |