Record Productivity and Unprecedented Molecular Weight for Ring‐Opening Copolymerization of Epoxides and Cyclic Anhydrides Enabled by Organoboron Catalysts

• Published in: Angewandte Chemie International Edition Vol. 60; no. 35; pp. 19253 - 19261
• Main Authors: Xie, Rui, Zhang, Yao‐Yao, Yang, Guan‐Wen, Zhu, Xiao‐Feng, Li, Bo, Wu, Guang‐Peng
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 23.08.2021
• Edition: International ed. in English
• Subjects: Catalysts; Copolymerization; Crystal structure; Cyclohexane; Epoxides; high molecular weight; metal-free; Molecular weight; NMR; Nuclear magnetic resonance; Phthalic anhydride; Polydispersity; polyester; Polyester resins; Polyesters; reaction mechanisms; Ring opening polymerization; ring-opening copolymerization; Side reactions; Structural analysis
• ISSN: 1433-7851; 1521-3773; 1521-3773
• DOI: 10.1002/anie.202104981

Producing polyesters with high molecular weight (Mn) through ring‐opening copolymerization (ROCOP) of epoxides with cyclic anhydrides remains a major challenge. Herein, we communicate a metal‐free, highly active, and high thermoresistance system for the ROCOP of epoxides with cyclic anhydrides to prepare polyesters (13 examples). The organoboron catalysts can endure a reaction temperature as high as 180 °C for the ROCOP of cyclohexane oxide (CHO) with phthalic anhydride (PA) without the observation of any side reactions. The average Mn of the produced poly(CHO‐alt‐PA) climbed to 94.5 kDa with low polydispersity (Ð=1.19). Furthermore, an unprecedented turnover number of 9900, equivalent to an efficiency of 7.4 kg of polyester/g of catalyst, was achieved at a feed ratio of CHO/PA/catalyst=20000:10000:1 at 150 °C. Kinetic studies, crystal structure analysis, 11B NMR spectra, and DFT calculations provided mechanistic justification for the effectiveness of the catalyst system. Ring‐opening copolymerization of epoxides and cyclic anhydrides by organoboron catalysts is presented. In view of their facile preparation and unprecedented performance (thermostability, reactivity, and productivity), the catalysts provided here hold promise in pushing ROCOP of epoxides with cyclic anhydrides to the industry line.