关键词: 卤代芳烃, 区域选择性, 亲电取代卤化反应, 协同催化

Abstract: Electrophilic halogenation of arenes represents a fundamental method for synthesizing aryl halides, crucial in the construction of various agrochemicals, materials, and pharmaceuticals. However, achieving regioselectivity in the halogenation of electron-rich arenes has posed a persistent challenge. This experiment demonstrates a synergistic catalytic approach for halogenating arenes bearing electron-donating substituents under mild conditions, offering a highly selective pathway to aryl halides. The utilization of hydrogen bonding between a Brønsted acid and the protic solvent nitromethane facilitates this transformation, effectively addressing the aforementioned challenge. The experiment not only enhances students’ understanding of electrophilic halogenation reactions of arenes but also imparts knowledge on self-assembly, synergistic catalysis, and Lewis acid-base catalysis. Furthermore, it deepens students’ comprehension of reaction mechanisms and ionic intermediates. The experiment comprises three main components: synthesis of brominated aromatics, mechanism exploration, and applicability assessment. It encompasses various organic laboratory techniques, including reaction monitoring, purification, and product characterization. With a duration of 7 hours and ensuring high safety, this experiment is suitable for undergraduate teaching. Moreover, it serves to strengthen students’ fundamental experimental skills while fostering their capacity for scientific research innovation and practice, preparing them for future scientific endeavors.

Key words: Aryl halide, Regioselectivity, Electrophilic halogenation, Synergistic catalysis