Lanthanum-Lithium Synergistic Catalysis for the Synthesis of Highly Isotactic Cyclic and Linear Poly(mandelic acid)
Yanping Song1,2, Deyue Cao3, Dan Yuan1, Yunjie Luo4(罗云杰)*, Gen Luo3(罗根)*, Miao Hong2(洪缪)*, Yingming Yao1(姚英明)*
1Key Laboratory of Organic Synthesis of J2iangsu Province, State and Local Joint Engineering Laboratory for Novel Functional Polymeric Materials,College of Chemistry, Chemical Engineering & Materials Science, Soochow University, Suzhou, Jiangsu, 215123, China
2State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy ofSciences, Shanghai200032,China
3InstitutesofPhysicalScienceandInformation Technology,AnhuiUniversity,Hefei230601,China
4School ofMaterialsScienceandChemical Engineering,NingboUniversity,Ningbo315211,China
Macromolecules2025, 58, 21, 11981–11990
Abstract: The ring-opening polymerization (ROP) of O-carboxyanhydrides (OCAs) efficiently produces diverse poly(α-hydroxyalkanoic acid) (PAHA) with functional groups that are difficult to achieve via lactone polymerization. Poly(mandelic acid) (PMA), synthesized from manOCA (OCA derived from mandelic acid), is a promising polymeric material because of its high glass transition (Tg) and thermal decomposition temperatures (Td). However, the synthesis of highly isotactic PMA remains challenging due to the inherent tendency to undergo epimerization during polymerization. Herein, the simple bimetallic rare-earth metal amide complex [(Me3Si)2N]3La(μ-Cl)Li(THF)3 was developed as an efficient catalyst to catalyze the ROP of L-manOCA. This catalyst effectively suppressed epimerization with high activity to afford highly isotactic PMA. The remarkable activity and isomerization selectivity were attributed to the synergistic effect between the rare-earth metal and lithium atoms in [(Me3Si)2N]3La(μ-Cl)Li(THF)3, as confirmed by density functional theory (DFT) calculations. Furthermore, the catalyst enabled precise control over polymer topology (cyclic vs linear) by modulating BnOH addition and reaction temperature. This catalyst also exhibited remarkable polymerization activity toward OCA derivatives with high isotactic selectivity. These findings lay the foundation for the development of efficient catalysts for the synthesis of highly isotactic PAHA polymers from OCA monomers.
Article information: https://doi.org/10.1021/acs.macromol.5c02560
