PURPOSE: To obtain a maleimide compound in high yield at a remarkably improved catalytic performance by adding and reacting a tert. amine to recovered catalyst in the dehydrative imidation of an N-substituted maleinamic acid in the presence of a tin-based catalyst.
CONSTITUTION: An N-substituted maleimide is produced by using metallic tin or a tin compound as a catalyst, heating and dehydrating an N-substituted maleinamic acid in a mixed solvent consisting of an organic solvent forming an azeotropic mixture with water and an organic aprotic polar solvent and carrying out the dehydrative imidation of the acid while removing the formed water by azeotropic distillation. The catalyst is recovered from the reaction liquid, added with 0.01-10mol (preferably 0.1-5mol) of a tert. amine based on 1g-atom of tin and reused in the dehydrative imidation reaction.
OU KINGAI
FUKUMURA KUNIMITSU
TSUDA YUMIKO
