PROCESSES FOR PRODUCING MALEAMIC ACID, ESTER THEREOF AND MALEIMIDE

摘要

A process for producing an N-unsubstituted maleimide by imidating an N-unsubstituted maleamic ester through elimination of alcohol molecule and ring closure, wherein use is made of an acidic catalyst or mono(cyclo)alkyl sulfate and it is preferable to lower the alcohol concentration in the reaction mixture. When maleamic acid is reacted with an alcohol by using an inert solvent and an acidic catalyst, a mixture of maleamic with an acidic catalyst, or a mono(cyclo)alkyl sulfate, a corresponding maleamic ester is obtained. Maleamic acid is produced by the reaction of maleic anhydride with ammonia in an inert solvent, which reaction is conducted by feeding a solution of maleic anhydride in an inert solvent into a reactor and feeding ammonia gas into an open space of the reactor to cause the ammonia to be absorbed in the solution via the surface of contact of the solution with the gas.