| 摘要 |
PURPOSE:To obtain the subject compounds of high purity in high yield by the imide forming ring closure reaction with dehydration of an N-substituted maleic acid amide, using a specific acid catalyst in an uniform reaction system, while azeotropically removing the produced water. CONSTITUTION:The N-substituted maleic acid amide of formula I where R<1> is alkyl or cycloalkyl derived from maleic anhydride and primary amines, is exposed to the imide forming ring closure reaction with dehydration in the presence of an acid catalyst and a polymerization inhibitor in an aromatic hydrocarbon solvent which is capable of forming azeotropic mixture with water, to produce an N-substitued maleimide of formula II with azeotropic removal of produced water. As the acid catalyst, sulfonic acids and an acid amine mixture obtained from sulfonic acids and above primary amines, are used. Further, the amount of the acid amine mixture used in the acid catalyst is equal to or more than 0.8 equivalent against the amount of sulfonic acids. After the end of reaction it, is favorable to recover the acid catalyst from the reaction system for its reuse. The compounds of equation II is useful as an improving agent of heat resistance of resins, and an intermediate for medicines or agrichemicals. |
