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Monomer insertion mechanism of ring-opening polymerization of ɛ-caprolactone with yttrium alkoxide intermediate: A DFT study

✍ Scribed by Jinzhi Liu; Jun Ling; Xin Li; Zhiquan Shen

Publisher
Elsevier Science
Year
2009
Tongue
English
Weight
587 KB
Volume
300
Category
Article
ISSN
1381-1169

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✦ Synopsis

The mechanism of -caprolactone (CL) insertion into a Y-OCH 3 bond was investigated using density functional theory (DFT) calculations. The optimized geometries and corresponding Gibbs-free energies of the intermediates were obtained, which confirmed a four-step coordination-insertion mechanism. The coordination of CL onto yttrium center led to a nucleophilic addition of the carbonyl group of CL, followed by an intramolecular alkoxide ligand exchange. A monomer insertion was completed by the CL ring opening via acyl-oxygen bond cleavage. The formation of the five-coordinated yttrium intermediate, 3, was found to be the rate-determining step. This study could be applicable to ring-opening polymerisation (ROP) of CL initiated by lanthanide metal complexes.

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A density functional theory study of the mechanisms of scandium-alkoxide initiated coordination–insertion ring-opening polymerization of cyclic esters
✍ Jun Ling; Jingguo Shen; Thieo E. Hogen-Esch 📂 Article 📅 2009 🏛 Elsevier Science 🌐 English ⚖ 346 KB

The generally accepted coordination-insertion mechanisms of scandium-alkoxide initiated ring-opening polymerizations of 3-caprolactone (CL), trimethylene carbonate (TMC) and (S,S)-lactide (LLA) were investigated using density functional theory calculations. The geometries and corresponding energies