PURPOSE: To produce a bismaleimide in high purity and yield without using acetic anhydride and heavy metal salt by successively supplying and reacting maleic anhydride to a reactor containing a diamine compound refluxed under heating in the presence of a catalyst.
CONSTITUTION: Maleic anhydride is successively supplied to a reactor containing a diamine compound of formula I (X is direct bond, 1-20C bivalent hydrocarbon group, hexafluorinated isopropylidene, carbonyl, thio or sulfonyl; the position of N atom is p-, o- or m- relative to X; Y1 to Y4 are H, lower alkyl, lower alkoxy, Cl or Br) refluxed under heating in the presence of an acidic or basic catalyst and made to react with the diamine while removing the produced water from the system to obtain a bismaleimide of formula II. The feeding rate of maleic anhydride is preferably adjusted to get a maleic anhydride/ diamine compound molar ratio of 2.0-2.5. The reaction solvent is a mixed solvent consisting of an aprotic organic solvent and an organic solvent capable of forming azeotropic mixture with water.
OBUCHI SEIJI
OTA MASAHIRO
