EP0165574A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Method for production of maleimides
Assignee: Nippon Shokubai Co Ltd
•
Filing: 1985-06-14
•
Granted: —
•
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° to 250°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
EP
Data Source
google_patents
Last Synchronized
2026-11-09 17:45
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
66 words
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 ° to 250 °C while removing the formed water in the form of an azeotrope with said organic solvent and thereafter purifying the produced maleimides.
Claim 2
Independent Claim
66 words
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 ° to 250 °C while removing the formed water in the form of an azeotrope with said organic solvent and thereafter purifying the produced 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
18 words
A method according to' Claim 2, wherein said reaction temperature is in the range of 200 to 250°C.
Claim 5
Dependent Claim
37 words
A method according to Claim 1, wherein said ring-closure imidation is carried out in the presence of a metal-containing compound selected from the group consisting of zinc, chromium, cobalt, nickel, iron, aluminum, and palladium and a stabilizer.
Claim 6
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 7
Dependent Claim
36 words
A method according to Claim 1, wherein said acid catalyst is at least one acid selected from the group consisting of sulfuric acid, sulfuric acid anhydride, p-toluene sulfonic acid, ortho-phosphoric acid, meta-phosphoric acid and pyro-phosphoric acid.
Claim 8
Dependent Claim
15 words
A method according to Claim 4, wherein said metal-containing compound is a zinc containing compound.
Claim 9
Dependent Claim
15 words
A method according to Claim 4, wherein said metal-containing compound is an acetic acid salt.
Claim 10
Dependent Claim
33 words
A method according to Claim 4, wherein said stabilizer is at least one compound selected from the group consisting of quinones, phenols, thiodipropionic acid esters, dithiocarbamates, salicylates, alkyldiphenylamines, phenothiazines mercaptoimidazoles and triphenyl phosphates.
Claim 11
Dependent Claim
39 words
A method according to Claim 4, 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 12
Dependent Claim
72 words
ll. 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 13
Dependent Claim
48 words
A method according to Claim 11, 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 14
Dependent Claim
31 words
A method according to Claim 12, 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 15
Dependent Claim
22 words
A method according to Claim 11, wherein an amount of said acid is 1 to 30% by weight to said maleinamic acids.
Claim 16
Dependent Claim
26 words
A method according to Claim 11, wherein said washing with water is carried out using 1 to 5 times of water to said starting maleinamic acids.
Claim 17
Dependent Claim
27 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.
Claim 18
Dependent Claim
24 words
A method according to Claim 16, wherein an amount of said stabilizer is not less than 10 ppm (by weight) to said crude maleimides.
Claim 19
Dependent Claim
23 words
A method according to Claim 16, wherein the amount of said stabilizer is 100 to 2,000 ppm (by weight) to said crude maleimides.
Claim 20
Dependent Claim
30 words
A method according to Claim 16, 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 21
Dependent Claim
33 words
A method according to Claim 16, wherein said stabilizer is at least one member selected from the group consisting of quinones, phenols, thiodipropionaic, acid esters, dithiocarbamates, salicylates, alkyldiphenylamines, phenothiazines, mercaptoimidazoles and triphenyl phosphates.
Claim 22
Dependent Claim
11 words
A method according to Claim 20, wherein said stabilizer is dithiocarbamates.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
Maintenance schedule is calculated for granted US utility patents.