US4623734A
Expired / Lapsed
US
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Method for production of maleimides
Assignee: Nippon Shokubai Co Ltd
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Filing: 1985-06-14
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Granted: 1986-11-18
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Expires: 2005-06-14
Abstract
Abstract A method for the production of maleimides, which comprises subjecting maleinamic acids to ring-closure imidation in an organic solvent capable of forming an azeotrope with water in the presence of an acid catalyst at a temperature in the range of 120 DEG to 250 DEG C. while removing the formed water in the form of an azeotrope with said organic solvent and thereafter purifying the produced maleimides.
Inventors
- 👤 Yuichi Kita
- 👤 Kentaro Sakamoto
- 👤 Masao Baba
- 👤 Atsushi Okubo
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 17:20
CPC Classifications
C; C07; C07D; C07D211/00; C07D207/00; C07D207/02; C07D207/44; C07D207/444; C07D207/448; C07D209/00; C07D209/02; C07D209/44; C07D209/48
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
106 words
A method for the production of maleimides, which comprises subjecting maleinamic acids to ring-closure imidation in an aprotic non-polar organic organic solvent capable of forming an azeotrope with water in the presence of an acid catalyst and a metal-containing compound selected from the group consisting of oxides, acetates, maleates, succinates, nitrates, phosphates, chlorides, bromides, of zinc, chromium, cobalt, nickel, iron, aluminum iodides, and sulfates of zinc, chromium, cobalt, nickle, iron, aluminum, and palladium at a temperature in the range of 120° to 250° C. while removing the formed water in the form of an azeotrope with said organic solvent and thereafter purifying the produced crude maleimides.
Claim 2
Independent Claim
106 words
A method for the production of maleimides, which comprises subjecting maleinamic acids to ring-closure imidation in an aprotic non-polar organic organic solvent capable of forming an azeotrope with water in the presence of an acid catalyst and a metal-containing compound selected from the group consisting of oxides, acetates, maleates, succinates, nitrates, phosphates, chlorides, bromides, of zinc, chromium, cobalt, nickel, iron, aluminum iodides, and sulfates of zinc, chromium, cobalt, nickle, iron, aluminum, and palladium at a temperature in the range of 120° to 250° C. while removing the formed water in the form of an azeotrope with said organic solvent and thereafter purifying the produced crude maleimides.
Claim 3
Dependent Claim
19 words
A method according to claim 1, wherein said reaction temperature is in the range of 180° to 250° C.
Claim 4
Dependent Claim
19 words
A method according to claim 2, wherein said reaction temperature is in the range of 200° to 250° C.
Claim 5
Dependent Claim
24 words
A method according to claim 1, wherein said acid catalyst is used in an amount of 2 to 80 mol% to said maleinamic acids.
Claim 6
Independent Claim
137 words
A method for the production of a maleimide which comprises subjecting a maleinamic acid to ring closure imidation in an aprotic non-polar organic solvent capable of forming an azeotrope with water in the presence of an acid catalyst consisting of at least one acid selected from the group consisting of sulfuric acid, sulfuric acid anhydride, p-toluene sulfonic acid, ortho-phosphoric acid, metaphosphoric acid and pyrophosphoric acid, and a metal-containing compound selected from the group consisting of oxides, acetates, maleates, succinates, nitrates, phosphates, chlorides, bromides, of zinc, chromium, cobalt, nickel, iron, aluminum and iodides, and sulfates of zinc, chromium, cobalt, nickel, iron, aluminum, and palladium at a temperature in the range of 120° C. to 250° C. while removing the formed water in the form of an azeotrope with said organic solvent and thereafter purifying the produced crude maleimide.
Claim 7
Independent Claim
137 words
A method for the production of a maleimide which comprises subjecting a maleinamic acid to ring closure imidation in an aprotic non-polar organic solvent capable of forming an azeotrope with water in the presence of an acid catalyst consisting of at least one acid selected from the group consisting of sulfuric acid, sulfuric acid anhydride, p-toluene sulfonic acid, ortho-phosphoric acid, metaphosphoric acid and pyrophosphoric acid, and a metal-containing compound selected from the group consisting of oxides, acetates, maleates, succinates, nitrates, phosphates, chlorides, bromides, of zinc, chromium, cobalt, nickel, iron, aluminum and iodides, and sulfates of zinc, chromium, cobalt, nickel, iron, aluminum, and palladium at a temperature in the range of 120° C. to 250° C. while removing the formed water in the form of an azeotrope with said organic solvent and thereafter purifying the produced crude maleimide.
Claim 8
Dependent Claim
15 words
A method according to claim 1, wherein said metal-containing compound is a zinc containing compound.
Claim 9
Dependent Claim
15 words
A method according to claim 1, wherein said metal-containing compound is an acetic acid salt.
Claim 10
Dependent Claim
39 words
A method according to claim 1, wherein an amount of said metal-containing compound is 0.005 to 0.5 mol as the metal and an amount of said stabilizer is 0.005 to 0.5 mol per 100 mol of said maleinamic acids.
Claim 11
Dependent Claim
72 words
A method according to claim 1, wherein said purification comprises adding to said crude maleimides an organic acid or inorganic acid in an amount of at least 1% by weight based on the maleinamic acids used as the raw material, treating the resultant mixture at a temperature in the range of 5° to 100° C., and washing the resultant organic layer with the water thereby depriving the organic layer of water-soluble impurities.
Claim 12
Dependent Claim
48 words
A method according to claim 9, wherein said organic or inorganic acid is at least one acid selected from the group consisting of ortho-phosphoric acid, pyro-phosphoric acid, sulfuric acid, sulfuric acid anhydride, fuming sulfuric acid, methane sulfonic acid, chlorosulfonic acid, chloromaleic acid, para-toluene sulfonic acid and trifluoroacetic acid.
Claim 13
Dependent Claim
31 words
A method according to claim 10, wherein said acid is at least one acid selected from the group consisting of sulfonic acids, sulfuric acid, sulfuric acid anhydride and fuming sulfuric acid.
Claim 14
Dependent Claim
22 words
A method according to claim 9, wherein an amount of said acid is 1 to 30% by weight to said maleinamic acids.
Claim 15
Dependent Claim
26 words
A method according to claim 9, wherein said washing with water is carried out using 1 to 5 times of water to said starting maleinamic acids.
Claim 16
Dependent Claim
54 words
A method according to claim 1, wherein said purification comprises washing said crude maleimides with water and distilling the washed maleimides in the presence of a stabilizer, wherein said stabilizer is at least one member selected from the group consisting of quinones, phenols, thiodipropionoic acid esters, dithiocarbamates, salicylates, alkyldiphenylamines, phenothiazines, mercaptoimidazoles and triphenyl phosphates.
Claim 17
Dependent Claim
24 words
A method according to claim 14, wherein an amount of said stabilizer is not less than 10 ppm (by weight) to said crude maleimides.
Claim 18
Dependent Claim
23 words
A method according to claim 14, wherein the amount of said stabilizer is 100 to 2,000 ppm (by weight) to said crude maleimides.
Claim 19
Dependent Claim
30 words
A method according to claim 14, wherein said washing with water is carried out until an acid content in said crude maleimides decreases to not more than 0.5% by weight.
Claim 20
Dependent Claim
11 words
A method according to claim 14, wherein said stabilizer is dithiocarbamates.
Claim 21
Dependent Claim
46 words
A method according to claim 1, wherein said ring-closure imidation is carried out in the presence of a stabilizer, wherein said stabilizer is at least one member selected from the group consisting of quiinones, phenols, thiodipropionic acid esters, dithiocarbamates, salicylates, alkyldiphenylamines, phenothiazines, mercaptoimidazoles and triphenyl phosphates.
Claim 22
Dependent Claim
33 words
A method according to claim 19, wherein said stabilizer is at least one compound selected from the group consisting of quinones, phenols, thiodipropionic acid ester, dithiocarbamates, salicylates, alkyldiphenylamines, phenothiazines mercaptoimidazoles and triphenyl phosphates.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1989-11-17 | 1990-05-19 | 1990-11-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-11-17 | 1994-05-19 | 1994-11-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-11-17 | 1998-05-19 | 1998-11-18 | $7700.00 | Window Closed / Lapsed |