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US4289699A
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Process for the production of N-(hydroxyphenyl) maleimides
Assignee: Mitsui Toatsu Chemicals Inc
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Filing: 1979-10-26
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Granted: 1981-09-15
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Expires: 1999-10-26
Abstract
Abstract N-(hydroxyphenyl) maleimides of the general formula <IMAGE> where R' stands for H, CH3, C2H5, F, Cl, Br or I and n is an integer of 1-5 are produced by treating the corresponding maleamic acid or by treating the ester of said N-(hydroxyphenyl) maleimide at a temperature of 0 DEG -150 DEG C. in the presence of at least one dehydrating agent selected for the group consisting of oxides and oxyacids of sulfur or phosphorus and alkali metal and alkaline earth metal salts of the said oxyacids. The corresponding maleamic acid can be obtained by reacting an aminophenol having one or more hydroxyl groups on its phenyl nucleus with maleic anhydride. The esters of the N-(hydroxyphenyl maleimide) can be obtained by reacting said aminophenol and said maleic anhydride in the presence of a conventional acid anhydride dehydrating agent and a conventional imide-forming cyclization catalyst.
Inventors
- 👤 Masayuki Oba
- 👤 Motoo Kawamata
- 👤 Hikotada Tsuboi
- 👤 Nobuhito Koga
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 20:15
CPC Classifications
C; C07; C07D; C07D207/00; C07D207/02; C07D207/44; C07D207/444; C07D207/448
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
144 words
A process for the production of an N-(hydroxyphenyl)-maleimide expressed by the formula: ##STR9## where R' stands for H, CH 3 , C 2 H 5 , F, Cl, Br or I and n is 1 or 2, comprising admixing an N-(hydroxyphenyl)-maleimide ester expressed by the formula: ##STR10## where R stands for an alkyl group having 1 to 7 carbon atoms or a phenyl group, and R' and n each have the same meaning as indicated above, with at least one oxyacid selected from the group consisting of sulfuric acid, thiosulfuric acid, sulfurous acid, phosphoric acid, metaphosphoric acid and pyrophosphoric acid to dissolve said ester in said oxyacid at a temperature of 0°-150° C., the amount of said ester being within the solubility limit thereof in said oxyacid, and then admixing the resulting mixture with water to hydrolyze the ester and to precipitate said N-(hydroxyphenyl)-maleimide.
Claim 2
Dependent Claim
144 words
A process for the production of an N-(hydroxyphenyl)-maleimide expressed by the formula: ##STR9## where R' stands for H, CH 3 , C 2 H 5 , F, Cl, Br or I and n is 1 or 2, comprising admixing an N-(hydroxyphenyl)-maleimide ester expressed by the formula: ##STR10## where R stands for an alkyl group having 1 to 7 carbon atoms or a phenyl group, and R' and n each have the same meaning as indicated above, with at least one oxyacid selected from the group consisting of sulfuric acid, thiosulfuric acid, sulfurous acid, phosphoric acid, metaphosphoric acid and pyrophosphoric acid to dissolve said ester in said oxyacid at a temperature of 0°-150° C., the amount of said ester being within the solubility limit thereof in said oxyacid, and then admixing the resulting mixture with water to hydrolyze the ester and to precipitate said N-(hydroxyphenyl)-maleimide.
Claim 3
Dependent Claim
13 words
A process as claimed in claim 1 wherein said ester is N-(4-acetoxyphenyl) maleimide.
Claim 4
Dependent Claim
13 words
A process as claimed in claim 1 wherein said oxyacid is sulfuric acid.
Claim 5
Dependent Claim
22 words
A process as claimed in claim 1 wherein the temperature of the water is in the range of 0° to 30° C.
Claim 6
Dependent Claim
13 words
A process as claimed in claim 1 wherein said oxyacid is phosphoric acid.
Claim 7
Dependent Claim
18 words
A process as claimed in claim 1 wherein said ester is dissolved in a mixture of said oxyacids.
Claim 8
Dependent Claim
25 words
A process as claimed in claim 1 wherein the amount of said ester is not more than 90% of its solubility limit in said oxyacid.
Claim 9
Dependent Claim
176 words
A process for the production of an N-(hydroxyphenyl)-maleimide expressed by the formula: ##STR11## where R' stands for H, CH 3 , C 2 H 5 , F, Cl, Br or I and n is 1 or 2 comprising admixing an N-(hydroxyphenyl)-maleimide ester expressed by the formula: ##STR12## where R stands for an alkyl group having 1 to 7 carbon atoms or a phenyl group, and R' and n each have the same meaning as indicated above, with a solvent system consisting essentially of at least one oxyacid and at least one non-reactive solvent to dissolve said ester in said solvent system at a temperature of 0°-150° C., said oxyacid being selected from the group consisting of sulfuric acid, thiosulfuric acid, sulfurous acid, phosphoric acid, metaphosphoric acid and pyrophosphoric acid, said non-reactive solvent being selected from the group consisting of dimethylformamide, dimethylacetoamide, dimethylsulfoxide, and N-methyl-2-pyrolidone, the amount of said ester being within the solubility limit thereof in said solvent system, and then admixing the resulting mixture with water to hydrolyze the ester and to precipitate said N-(hydroxyphenyl)-maleimide.
Claim 10
Dependent Claim
176 words
A process for the production of an N-(hydroxyphenyl)-maleimide expressed by the formula: ##STR11## where R' stands for H, CH 3 , C 2 H 5 , F, Cl, Br or I and n is 1 or 2 comprising admixing an N-(hydroxyphenyl)-maleimide ester expressed by the formula: ##STR12## where R stands for an alkyl group having 1 to 7 carbon atoms or a phenyl group, and R' and n each have the same meaning as indicated above, with a solvent system consisting essentially of at least one oxyacid and at least one non-reactive solvent to dissolve said ester in said solvent system at a temperature of 0°-150° C., said oxyacid being selected from the group consisting of sulfuric acid, thiosulfuric acid, sulfurous acid, phosphoric acid, metaphosphoric acid and pyrophosphoric acid, said non-reactive solvent being selected from the group consisting of dimethylformamide, dimethylacetoamide, dimethylsulfoxide, and N-methyl-2-pyrolidone, the amount of said ester being within the solubility limit thereof in said solvent system, and then admixing the resulting mixture with water to hydrolyze the ester and to precipitate said N-(hydroxyphenyl)-maleimide.
Claim 11
Dependent Claim
15 words
A process as claimed in claim 8 wherein said non-reactive solvent is dimethylformamide or N-methyl-2-pyrolidone.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-09-14 | 1985-03-16 | 1985-09-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-09-14 | 1989-03-16 | 1989-09-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-09-14 | 1993-03-16 | 1993-09-15 | $7700.00 | Window Closed / Lapsed |