US4764263A
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Electrochemical synthesis of substituted aromatic amines in basic media
Assignee: ASHBROOK CLIFFORD L
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Filing: 1987-05-18
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Granted: 1988-08-16
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Expires: 2007-05-18
Abstract
Abstract Substituted amino aromatic compounds such as 3-amino-4-hydroxybenzoic acid are prepared by electrolytically reducing the corresponding nitro aromatic compound in a basic medium at temperatures below 60° C. and current densities greater than 50 milliamps per square centimeter. The aminohydroxybenzoic acids are useful in the preparation of polybenzoxazoles which are used to make fibers and composites having high strength and thermal stability.
Inventors
- 👤 Thomas D. Gregory
- 👤 Kenneth J. Stutts
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 22:19
CPC Classifications
C; C25; C25B; C25B3/00; C25B3/20; C25B3/25; C25B11/00; C25B11/04; C25B11/051; C25B11/073; C25B11/075; C25B11/081; C25B3/01; C25B3/07; C25B3/09
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
49 words
A process for preparing a substituted aromatic amine comprising electrolytically reducing a substituted nitro aromatic compound in an alkaline medium at a temperature less than about 60° C. and a current density of at least about 50 milliamps/square centimeter to yield at least about 50 percent of the amine.
Claim 2
Dependent Claim
49 words
A process for preparing a substituted aromatic amine comprising electrolytically reducing a substituted nitro aromatic compound in an alkaline medium at a temperature less than about 60° C. and a current density of at least about 50 milliamps/square centimeter to yield at least about 50 percent of the amine.
Claim 3
Dependent Claim
96 words
The process of claim 1 wherein the nitro aromatic compound is represented by the formula: ##STR2## wherein Ar is an aromatic ring structure, each R is independently hydrogen, alkyl or haloalkyl, each Z is independently an electron-releasing substituent in a position ortho or para to a nitro group, Y is carboxy, sulfo, cyano, carboxylate ester, aryl, and halo, m is an integer from 1 to 5, p is 0 or 1, n is an integer from 1 to 3 and o is an integer representing the remaining positions available for substitution on the aromatic ring structure.
Claim 4
Dependent Claim
76 words
A process for preparing a substituted aromatic amine comprising electrolytically reducing a substituted nitro aromatic compound selected from the group consisting of 3-nitro-4-hydroxybenzoic acid, 3-hydroxy-4-nitrobenzoic acid, 2-hydroxy-5-nitrobenzoic acid, 2-nitrophenol, 4-nitrophenol, 2-nitroanisole, 4-nitroanisole, 4-methyl-2-nitrophenol, 2-methyl-3-nitrophenol, 3-methyl-4-nitrophenol, 5-methyl-2-nitrophenol, 4-nitrophenetole and nitrotoluene or a mixture thereof in an alkaline medium at a temperature less than about 60° C. and a current density of at least about 50 milliamps/square centimeter to yield at least about 50 percent of the amine.
Claim 5
Dependent Claim
76 words
A process for preparing a substituted aromatic amine comprising electrolytically reducing a substituted nitro aromatic compound selected from the group consisting of 3-nitro-4-hydroxybenzoic acid, 3-hydroxy-4-nitrobenzoic acid, 2-hydroxy-5-nitrobenzoic acid, 2-nitrophenol, 4-nitrophenol, 2-nitroanisole, 4-nitroanisole, 4-methyl-2-nitrophenol, 2-methyl-3-nitrophenol, 3-methyl-4-nitrophenol, 5-methyl-2-nitrophenol, 4-nitrophenetole and nitrotoluene or a mixture thereof in an alkaline medium at a temperature less than about 60° C. and a current density of at least about 50 milliamps/square centimeter to yield at least about 50 percent of the amine.
Claim 6
Dependent Claim
23 words
The process of claim 3 wherein the nitro aromatic compound is a nitrohydroxybenzoic acid or a mixture of two or more nitrohydroxybenzoic acids.
Claim 7
Dependent Claim
12 words
The process of claim 4 wherein the nitrohydroxybenzoic acid is 3-nitro-4-hydroxybenzoic acid.
Claim 8
Dependent Claim
45 words
The process of claim 1 which is conducted in an electrolytic cell having a cathode of a metal which is non-corrosive under the conditions of the reduction process and an anode of a stable conductor which is capable of generating oxygen in the alkaline medium.
Claim 9
Dependent Claim
29 words
The process of claim 1 wherein the cathode is copper, stainless steel, nickel or a conductive carbon-containing material and the anode is ruthenium on titanium, platinum, palladium or nickel.
Claim 10
Dependent Claim
15 words
The process of claim 7 wherein the cathode is copper and the anode is nickel.
Claim 11
Dependent Claim
16 words
The process of claim 6 wherein the cathode and anode are separated by an ion-exchange membrane.
Claim 12
Dependent Claim
13 words
The process of claim 9 wherein the ion-exchange membrane is a cation-exchange membrane.
Claim 13
Dependent Claim
22 words
The process of claim 1 wherein the pH of the alkaline medium is at least 8 and the medium contains an electrolyte.
Claim 14
Dependent Claim
13 words
The process of claim 11 wherein the electrolyte is an alkali metal hydroxide.
Claim 15
Dependent Claim
19 words
The process of claim 1 wherein the current density is from about 50 to about 300 mA/cm 2 .
Claim 16
Dependent Claim
19 words
The process of claim 13 wherein the current density is from about 75 to about 250 mA/cm 2 .
Claim 17
Dependent Claim
19 words
The process of claim 14 wherein the current density is from about 100 to about 150 mA/cm 2 .
Claim 18
Dependent Claim
19 words
The process of claim 1 wherein the temperature is in the range from about 0° C. to 60° C.
Claim 19
Dependent Claim
49 words
The process of claim 1 wherein the electrolytic reduction is carried out in an electrolytic cell having a catholyte and an anolyte both of which contain the alkaline medium and are defined by a separation means which enables the conductance of current via ion transport through the separation means.
References Cited (Backward Citations)
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| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1991-08-16 | 1992-02-15 | 1992-08-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-08-16 | 1996-02-15 | 1996-08-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-08-16 | 2000-02-15 | 2000-08-16 | $7700.00 | Window Closed / Lapsed |