Patent EP0372922A2 successfully refreshed from Google Patents.
EP0372922A2
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Preparation process of N-substituted maleimides
Assignee: Mitsui Toatsu Chemicals Inc
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Filing: 1989-12-06
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Granted: —
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Expires: 2009-12-06
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
EP
Data Source
google_patents
Last Synchronized
2026-11-09 21:11
CPC Classifications
C; C07; C07D; C07D207/00; C07D207/02; C07D207/44; C07D207/444; C07D207/448; C07D207/452
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
107 words
1) 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, characterised by 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
107 words
1) 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, characterised by 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
47 words
2) The process of claim 1 wherein the N-substituted maleamic acid is selected from 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
42 words
3) The process of claim 1 wherein the N-substituted maleamic acid is selected from 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, and the polymeric homologue 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, and N,N′-(4,4′-p-xylylenediphenyl) bis-maleamic acid and the polymeric homologue.
Claim 5
Dependent Claim
47 words
4) The process of claim 1, 2 or 3 where the catalyst is selected from one or more of a zinc salt of N-substituted mono-, bis- and poly-maleamic acid and zinc salt adduct obtained by coordinating water of crystallization or a neutral ligand to said zinc salt.
Claim 6
Dependent Claim
66 words
5) The process of claim 1, 2 or 3 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
23 words
6) The process of claim 1, 2 or 3 wherein the catalyst is metallic zinc in powder, granule, block, ribbon or film form.
Claim 8
Dependent Claim
16 words
7) The process of claim 1, 2 or 3 wherein the catalyst is a zinc halide.
Claim 9
Dependent Claim
25 words
8) The process of claim 1, 2 or 3 wherein the catalyst is the reaction mixture of a zinc halide and weak organic carboxylic acid.
Claim 10
Dependent Claim
22 words
9) The process of claim 1, 2 or 3 wherein the catalyst is a zinc salt of a weak organic carboxylic acid.
Claim 11
Dependent Claim
13 words
10) The process of claim 9 wherein the zinc salt is zinc acetate.
Claim 12
Dependent Claim
18 words
11) The process of claim 1, 2 or 3 wherein the catalyst is zinc oxide or zinc hydroxide.
Claim 13
Dependent Claim
16 words
12) The process of claim 1, 2 or 3 wherein the catalyst is a zinc chelate.
Claim 14
Dependent Claim
12 words
13) The process of claim 12 wherein the catalyst is zinc acetylacetonate.
Claim 15
Dependent Claim
28 words
14) The process of any preceding claim wherein the starting N-substituted maleamic acid is produceed in situ by the reaction of the corresponding maleic anhydride and primary amine.
Claim 16
Dependent Claim
36 words
15) The process of any preceding claim wherein the organic solvent capable of forming water azeotrope is one or more of cyclohexane, benzene, toluene, ethylbenzene, xylene, chlorobenzene, anisole, dichloroethane, diethoxyethane, cyclohexanone, methyl ethyl ketone and trioxane.
Claim 17
Dependent Claim
31 words
16) The process of any preceding claim 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
27 words
17) The process of any claims 1-15 wherein the organic solvent capable of forming water azeotrope is a xylene and the organic aprotic polar solvent is dimethylformamide.
Claim 19
Dependent Claim
24 words
18) The process of any preceding claim wherein the solvent mixture contains from 0.1 to 50% by volume of the organic aprotic polar solvent.
Claim 20
Dependent Claim
25 words
19) The process of any preceding claim 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
29 words
20) The process of claim 2 or any of claims 4-19 wherein N-substituted maleamic acid is produced in situ without isolation by the reaction of maleic anhydride with aniline.
Claim 22
Dependent Claim
26 words
21) The process of any preceding claim 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
22) The process of claim 1 wherein the N-substituted maleamic acid is produced in situ without isolation, in the concentration of the 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 then submitted to dehydrating imidization under azeotropic distillation of the reaction generated water in the presence as the catalyst of one or more of: a zinc salt of said acid, metallic zinc, or a zinc compound such as zinc chloride, zinc acetate, zinc oxide, zinc hydroxide and zinc actylacetonate in the amount of 0.005 to 0.02 gram atom of zinc per mole of said acid, thereby producing N-phenylmaleimide.
References Cited (Backward Citations)
No citation records indexed.
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