US5175309A
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Preparation process of n-substituted maleimides
Assignee: Mitsui Toatsu Chemicals Inc
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Filing: 1989-12-08
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Granted: 1992-12-29
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Expires: 2009-12-08
Abstract
Abstract A process for the preparation of N-substituted maleimides by conducting heat-dehydration and dehydrating imidization of N-substituted maleamic acids under azeotropic distillation of generated water in a solvent mixture containing a solvent capable of forming water azeotrope and an organic aprotic polar solvent, in the presence as catalyst of a zinc salt of a maleamic acid, metallic zinc or a zinc compound which forms a zinc salt of the N-substituted maleamic acid in the reaction system.
Inventors
- 👤 Ryuichiro Tsumura
- 👤 Kunimitsu Fukumura
- 👤 Teruo Muraishi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 17:19
CPC Classifications
C; C07; C07D; C07D207/00; C07D207/02; C07D207/44; C07D207/444; C07D207/448; C07D207/452
Claims Analysis
Total Claims: 24
Claim 1
Independent Claim
109 words
In a process for the preparation of N-substituted maleimide by heat-dehydrating N-substituted maleamic acid in a solvent mixture containing an organic solvent capable of forming water azeotrope and an organic aprotic polar solvent and simultaneously conducting a dehydrating imidization reaction under azeotropic distillation of the reaction generated water, the improvement which comprises conducting the dehydrating imidization in the absence of a Broensted acid having a pKa of 3 or less and in the presence as reaction catalyst of a catalytically effective amount of a zinc salt of the maleamic acid, metallic zinc or a zinc compound which forms a zinc salt of the maleamic acid in the reaction system.
Claim 2
Dependent Claim
109 words
In a process for the preparation of N-substituted maleimide by heat-dehydrating N-substituted maleamic acid in a solvent mixture containing an organic solvent capable of forming water azeotrope and an organic aprotic polar solvent and simultaneously conducting a dehydrating imidization reaction under azeotropic distillation of the reaction generated water, the improvement which comprises conducting the dehydrating imidization in the absence of a Broensted acid having a pKa of 3 or less and in the presence as reaction catalyst of a catalytically effective amount of a zinc salt of the maleamic acid, metallic zinc or a zinc compound which forms a zinc salt of the maleamic acid in the reaction system.
Claim 3
Dependent Claim
50 words
The process of claim 1 wherein the N-substituted maleamic acid is selected from the group consisting of N-methylmaleamic acid, N-butylmaleamic acid, N-octylmaleamic acid, N-dodecylmaleamic acid, N-stearylmaleamic acid, N-cyclohexylmaleamic acid, N-phenylmaleamic acid, N-(o-tolyl)maleamic acid, N-dodecylphenylmaleamic acid, N-chlorophenylmaleamic acid, N-dichlorophenylmaleamic acid, N-(p-hydroxyphenyl)maleamic acid, N-(o- or p-methoxyphenyl)maleamic acid, N-(m-hydroxycarbonylphenyl)maleamic acid and N-(m-nitrophenyl)maleamic acid.
Claim 4
Dependent Claim
39 words
The process of claim 1 wherein the N-substituted maleamic acid is selected from the group consisting of N,N'-(m- or p-phenylene)bis-maleamic acid, N,N'-(2,4-tolylene)bis-maleamic acid, N,N'-(4,4'-diphenylmethane)bis-maleamic acid, N,N'-(4,4'-diphenylether)bis-maleamic acid, N,N'-(4,4'-diphenylketone)bis-maleamic acid, N,N'-(4,4'-diphenyldisulfide)bis-maleamic acid, N,N'-(4,4'-diphenylsulfone)bis-maleamic acid, N,N-(4,4'-p-xylylenediphenyl)-bis-maleamic acid, and polymeric homologues thereof.
Claim 5
Dependent Claim
48 words
The process of claim 1 wherein the catalyst is selected from the group consisting of one or more of a zinc salt of N-substituted mono-, bis- and poly-maleamic acid and a zinc salt adduct obtained by coordinating water of crystallization or a neutral ligand to said zinc salt.
Claim 6
Dependent Claim
62 words
The process of claim 1 wherein the catalyst is one or more of the zinc salt of N-methylmaleamic acid, N-butyl-maleamic acid, N-dodecylmaleamic acid, N-stearylmaleamic acid, N-cyclohexylmaleamic acid, N-phenylmaleamic acid, N-tolylmaleamic acid, N,N'-(m- or p-phenylene)bis-maleamic acid, N,N'-(2,4-tolylene)bis-maleamic acid, N,N'-(4,4'-diphenylmethane)bis-maleamic acid, N,N'-(4,4'-diphenylether)bis-maleamic acid, N,N'-(4,4'-p-xylylenediphenyl)bis-maleamic acid and a zinc salt adduct obtained by coordinating water of crystallization or a neutral ligand to said zinc salt.
Claim 7
Dependent Claim
19 words
The process of claim 1 wherein the catalyst is metallic zinc in powder, granule, block, ribbon or film form.
Claim 8
Dependent Claim
12 words
The process of claim 1 wherein the catalyst is a zinc halide.
Claim 9
Dependent Claim
21 words
The process of claim 1 wherein the catalyst is the reaction mixture of a zinc halide and weak organic carboxylic acid.
Claim 10
Dependent Claim
17 words
The process of claim 1 whrein catalyst is a zinc salt of a weak organic carboxylic acid.
Claim 11
Dependent Claim
12 words
The process of claim 8 wherein the zinc salt is zinc acetate.
Claim 12
Dependent Claim
14 words
The process of claim 1 wherein the catalyst is zinc oxide or zinc hydroxide.
Claim 13
Dependent Claim
12 words
The process of claim 1 wherein the catalyst is a zinc chelate.
Claim 14
Dependent Claim
11 words
The process of claim 11 wherein the catalyst is zinc acetylecetonate.
Claim 15
Dependent Claim
26 words
The process of claim 1 wherein the starting N-substituted maleamic acid is produced in situ by the reaction of the corresponding maleic anhydride and primary amine.
Claim 16
Dependent Claim
34 words
The process of claim 1 wherein the organic solvent capable of forming water azeatrope is one or more of cyclohexane, benzene, toluene, ethylbenzene, xylene, chlorobenzene, anisole, dichloroechane, diethoxyethane, cyclohexanone, methyl ethyl ketone and trioxane.
Claim 17
Dependent Claim
29 words
The process of claim 1 wherein the organic aprotic polar solvent is one or more of dimethylformamide, dimethylacetamide, dimethylsulfoxide, sulfolane, methyl isobutyl ketone, γ-butyrolactone, hexamethylphosphoramide N-methylpyrrolidone, tetramethylurea and 1,3-dimethyl-2-imidazolidinone.
Claim 18
Dependent Claim
25 words
The process of claim 1 wherein the organic solvent capable of forming water azeotrope is a xylene and the organic aprotic polar solvent is dimethylformamide.
Claim 19
Dependent Claim
22 words
The process of claim 1 wherein the solvent mixture contains from 0.1 to 50% by volume of the organic aprotic polar solvent.
Claim 20
Dependent Claim
23 words
The process of claim 1 wherein the concentration of the N-substituted maleamic acid in the reaction system is about 0.1 to 5 mol/l.
Claim 21
Dependent Claim
23 words
The process of claim 2 wherein N-substituted maleamic acid is produced in situ without isolation by the reaction of maleic anhydride with aniline.
Claim 22
Dependent Claim
24 words
The process of claim 1 wherein the reaction and the purification of the reaction product are conducted in the presence of a polymerization inhibitor.
Claim 23
Dependent Claim
126 words
The process of claim 1, wherein the N-substituted maleamic acid is produced in situ without isolation, at a concentration of 0.5 to 3 mole per liter, by the reaction of maleic anhydride with aniline in the solvent mixture of xylene and dimethylformamide containing from 1 to 30% by volume of the latter, and said acid is subjected in situ to dehydration imidization under azeotropic distillation of the reaction-generated water and in the presence of the catalyst of a zinc salt of said acid, metallic zinc, a zinc compound selected from the group consisting of zinc chloride, zinc acetate, zinc oxide, zinc hydroxide, zinc actylacetonate, and mixtures thereof, in an amount from 0.005 to 0.02 gram atom of zinc per mole of said acid, thereby producing N-phenylmaleimide.
Claim 24
Dependent Claim
13 words
The process of claim 1, wherein the N-substituted maleamic acid is N,N'-(4,4'-p-xylenediphenyl)bis-maleamic acid.
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JPS6011465A
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