Green Synthesis of N ‐Substituted Maleimides via Solid‐State Grinding and Recyclable Benzoic Acid Catalysis

ABSTRACT

N ‐Substituted maleimides ( N ‐PMIs) are important building blocks for high‐performance materials, yet their conventional syntheses commonly rely on stoichiometric dehydrating agents, substantial solvent waste, and prolonged reaction times. Herein, we report a two‐step strategy comprising the solvent‐free mechanochemical formation of amic acid intermediates from amines and maleic anhydride, followed by benzoic acid (BA)‐mediated thermal cyclodehydration. Real‐time infrared thermography, together with FTIR and XRD characterization, revealed that mechanical force‐induced crystal fracture and the generation of fresh reactive surfaces promoted the rapid formation of these intermediates. The protocol was applied to 19 amine substrates, including both liquid and solid monoamines as well as diamines, and afforded bismaleimides (BMIs) in yields of up to 94%. BA served as both the reaction medium and catalyst and was recovered in 93% yield. This strategy significantly reduces organic solvent consumption, shortens reaction time, and simplifies purification, offering an alternative for the sustainable production of imide‐based derivatives.