King Abdullah University of Science and Technology (KAUST), Physical Sciences and Engineering Division, KAUST Catalysis Center, Polymer Synthesis Laboratory, Thuwal, 23955, Saudi Arabia.
King Abdullah University of Science and Technology (KAUST), Imaging and Characterization Core Lab, Thuwal, 23955, Saudi Arabia.
Angew Chem Int Ed Engl. 2023 Mar 27;62(14):e202218891. doi: 10.1002/anie.202218891. Epub 2023 Feb 23.
Organic halide salts in combination with metal or organic compound are the most common and essential catalysts in ring-opening copolymerizations (ROCOP). However, the role of organic halide salts was neglected. Here, we have uncovered the complex behavior of organic halides in ROCOP of epoxides or aziridine with cyclic anhydride. Coordination of the chain-ends to cations, electron-withdrawing effect, leaving ability of halide atoms, chain-end basicity/nucleophilicity, and terminal steric hindrance cause three types of side reactions: single-site transesterification, substitution, and elimination. Understanding the complex functions of organic halide salts in ROCOP led us to develop highly active and selective aminocyclopropenium chlorides as catalysts/initiators. Adjustable H-bonding interactions of aminocyclopropenium with propagating anions and epoxides create chain-end coordination process that generate highly reactive carboxylate and highly selective alkoxide chain-ends.
有机卤化物盐与金属或有机化合物结合，是开环共聚反应（ROCOP）中最常见和必不可少的催化剂。然而，有机卤化物盐的作用却被忽视了。在这里，我们揭示了有机卤化物在环氧化物或氮杂环丙烷与环状酸酐的 ROCOP 中的复杂行为。链末端与阳离子的配位、吸电子效应、卤原子的离去能力、链末端碱性/亲核性和末端空间位阻导致了三种类型的副反应：单部位酯交换、取代和消除。了解有机卤化物盐在 ROCOP 中的复杂功能，使我们能够开发出高活性和选择性的氨甲基环丙烯氯化物作为催化剂/引发剂。氨甲基环丙烯与增长阴离子和环氧化物的可调氢键相互作用，形成链末端配位过程，生成高反应性的羧酸酯和高选择性的烷氧基链末端。
