Patent US3545848A successfully refreshed from Google Patents.
Patent EP0213933A2 successfully refreshed from Google Patents.
EP0213933A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Maleimide manufacture
Assignee: Nippon Shokubai Co Ltd
•
Filing: 1986-08-28
•
Granted: —
•
Expires: 2006-08-28
Abstract
Abstract A method for the manufacture of a maleimide comprising the steps of heating a maleinamic acid in an organic solvent capable of forming an azeotrope with water in the presence of an acid catalyst while causing the water formed during the course of said reaction to be removed from the reaction system in the form of an azeotrope with said organic solvent thereby effecting ring-closure imidation of said maleinamic acid, which method is characterized by separating and recovering an acid catalyst layer from the organic solvent layer after completion of said ring-closure imidation and circulating said acid catalyst layer to the step of said ring-closure imidation for repeated use therein.
Inventors
- 👤 Kazuo Kishino
- 👤 Yuichi Kita
- 👤 Kentaro Sakamoto
- 👤 Masao Baba
- 👤 Yoichi Nakagawa
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-10 01:30
CPC Classifications
C; C07; C07C; C07C227/00; C07C227/04; C07C227/06; C07C227/08; C07D; C07D207/00; C07D207/02; C07D207/44; C07D207/444; C07D207/448; Y; Y02; Y02P; Y02P20/00; Y02P20/50; Y02P20/584
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
110 words
A method for the manufacture of a maleimide comprising the steps of heating a maleinamic acid in an organic solvent capable of forming an azeotrope with water in the presence of an acid catalyst while causing the water formed during the course of said reaction to be removed from the reaction system in the form of an azeotrope with said organic solvent thereby effecting ring-closure imidation of said maleinamic acid, which method is characterized by separating and recovering an acid catalyst layer from the organic solvent layer after completion of said ring-closure imidation and circulating said acid catalyst layer to the step of said ring-closure imidation for repeated use therein.
Claim 2
Independent Claim
110 words
A method for the manufacture of a maleimide comprising the steps of heating a maleinamic acid in an organic solvent capable of forming an azeotrope with water in the presence of an acid catalyst while causing the water formed during the course of said reaction to be removed from the reaction system in the form of an azeotrope with said organic solvent thereby effecting ring-closure imidation of said maleinamic acid, which method is characterized by separating and recovering an acid catalyst layer from the organic solvent layer after completion of said ring-closure imidation and circulating said acid catalyst layer to the step of said ring-closure imidation for repeated use therein.
Claim 3
Dependent Claim
22 words
A method according to Claim 1, wherein said reaction is carried out at a temperature in the range of 120° to 250°C.
Claim 4
Dependent Claim
20 words
A method according to Claim 1 or 2, wherein said reaction temperature is in the range of 130° to 220°C.
Claim 5
Dependent Claim
30 words
A method according to Claim 1, 2 or 3, wherein the amount of said acid catalyst is in the range of 2 to 400 mol% based on said maleinamic acid.
Claim 6
Independent Claim
45 words
A method according to any one of Claims 1 to 4, wherein said acid catalyst layer separated from said organic solvent layer is circulated to the subsequent step of ring-closure imidation as held at a temperature in the range of 120° to 250 0 C.
Claim 7
Independent Claim
42 words
A method according to any one of Claims 1 to 4, wherein said ring-closure imidation is carried out in the presence of a stabilizer and a compound containing at least one metal which is zinc, chromium, cobalt, nickel, iron, aluminium or palladium.
Claim 8
Independent Claim
35 words
A method according to any one of Claims 1 to 5, wherein said acid catalyst is at least one acid selected from sulphuric acid, sulphuric anhydride, p-toluenesulphonic acid, orthophosphoric acid, metaphosphoric acid, and pyrophosphoric acid.
Claim 9
Dependent Claim
14 words
A method according to Claim 6, wherein said metal-containing compound is a zinc-containing compound.
Claim 10
Dependent Claim
15 words
A method according to Claim 6 or 8, wherein said metal-containing compound is zinc acetate.
Claim 11
Dependent Claim
28 words
A method according to Claim 6, wherein said stabilizer is at least one compound selected from quinones, phenols, thio-dipropionic esters, dithiocarbamates, salicylates, alkylated diphenylamines, phenothiazines, mercaptoimidazoles and triphenylphosphates.
Claim 12
Independent Claim
42 words
A method according to any one of Claims 1 to 10, wherein said acid catalyst layer recovered from said organic solvent layer has 5 to 20% by weight of water added thereto before it is circulated to said step of ring-closure imidation.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
Maintenance schedule is calculated for granted US utility patents.