Ring-opening polymerization of l-lactide by organotin(IV)alkoxides, R2Sn(OPri)2: Estimation of the activation parameters

Malcolm H. Chisholm, Judith C. Gallucci, Clemens Krempner

Research output: Contribution to journalArticlepeer-review

25 Scopus citations

Abstract

The ring-opening polymerization of l-lactide, l-LA, to give poly-l-lactide by R2Sn(OPri)2 compounds, where R = Bun and p-XC6H4 (X = CF3, F, H, Me and OMe) has been studied in benzene over a temperature range. There is a relatively small variation in ΔH as a function of R with all the values falling within the range 11 ± 2 kcal mol-1. The entropy of activation, ΔS, is consistently large and negative, -50 ± 5 eu, supporting the view that the ring-opening event, the enchainment step involves a highly ordered transition state. The crystal and molecular structures of the compounds Ph2Sn(OPri)2, (p-FC6H4)2Sn(OPri)2 and (p-Me2NC6H4)3SnOPri are also reported. While the latter compound is monomeric in the solid state the former are both dimeric with a pair of bridging OPri ligands.

Original languageEnglish
Pages (from-to)4436-4444
Number of pages9
JournalPolyhedron
Volume26
Issue number15
DOIs
StatePublished - Sep 20 2007

Keywords

  • Alkoxides
  • Catalysis
  • Lactide polymerization
  • Tin

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