Process for the manufacture of maleimides

Abstract From the Canadian patent

The invention relates to a process for the manufacture of maleimides by cyclic dehydration of corresponding maleamic acids in the presence of, preferably, acetic anhydride and an alkaline earth metal compound (catalyst). Compared to known catalysts, especially nickel salts, the alkaline earth metal compounds used as catalysts according to the invention have the advantage that the manufacturing process gives substantially greater kettle yields, and that the compounds are non-toxic. Preferably, calcium oxide and calcium acetate are employed according to the invention. Corresponding barium compounds are also very suitable for use.