Organocatalysts for L-Lactide polymerization: 2-alkyl- and 2-aryl-1,1,3,3-tetramethylguanidines

• Published in: Molecular catalysis 2024-12, Vol.569, Article 114580
• Main Authors: Kamaraj, Rajiv, Ganta, Prasanna Kumar, Halima, Taoufik Ben, Huang, Fei, Penki, Venkata Sai Sashankh, Tseng, Hsi-Ching, Ding, Shangwu, Chen, Hsuan-Ying, Chen, Hsing-Yin
• Format: Article
• Language: English
• Subjects: Guanidine; L-Lactide; Ring-opening polymerization
• ISSN: 2468-8231; 2468-8231
• DOI: 10.1016/j.mcat.2024.114580

•A series of 2-alkyl- and 2-aryl-1,1,3,3-tetramethylguanidine derivatives were synthesized, and t their application in L-Lactide (LA) polymerization was studied.•Bn-TMG exhibited the highest catalytic activity compared to the mono 2-alkyl- and 2-aryl-1,1,3,3-tetramethylguanidine derivatives.•The catalytic activities of diguanidine derivatives exhibited higher catalytic activity than monoguanidine derivatives.•Bn-TMG is an organocatalyst for a controlled LA polymerization at 25 °C with excellent catalytic activity. A series of 2-alkyl- and 2-aryl-1,1,3,3-tetramethylguanidine derivatives were synthesized, and their application in L-Lactide (LA) polymerization was studied. Bn-TMG was the best catalyst in LA polymerization ( [Bn-TMG] = 5 mM, conversion = 94 % after 4 h at 25 °C) compared to other monoguanidine derivatives. In addition, the catalytic activities of C2-dTMG exhibited higher catalytic activity than Bn-TMG, nBu-TMG (monoguanidine derivatives), and C3-dTMG (diguanidine derivative). Density functional theory calculations revealed that Bn-TMG deprotonated benzyl alcohol enhanced benzyl alcohol's initiation ability to LA, and the protonated Bn-TMG activated LA ring-opening process by interacting with the ether oxygen atom of LA. Bn-TMG presented excellent catalytic activity and controllability for LA polymerization at 25 °C. [Display omitted]