International Journal of Biological Macromolecules 1999-01-01

Ring-opening polymerisation of beta-butyrolactone catalysed by distannoxane complexes: study of the mechanism.

Y Hori, T Hagiwara

Index: Int. J. Biol. Macromol. 25(1-3) , 237-45, (1999)

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Abstract

The mechanism of the ring-opening polymerisation of beta-butyrolactones was studied. The ring-opening polymerisation of BL catatlysed by distannoxane complexes is of a living nature. The polymerisation of racemic BL gave a predominantly syndiotactic P(3HB). The temperature effect on syndiospecificity was used to determine the activation energy (deltaE = Esyndiotactic - Eisotactic) for syndiotactic versus isotactic diad placement. The deltaE value was obtained as -1.49 kcal/mol. The steric control leading to the observed syndiospecificity is due predominantly to diastereomeric interactions between the Sn-coordinated P(3HB) chain end. having a specific chain end stereochemistry, and the incoming BL enantiomeric monomers. The catalytic cycle derived from the mechanism of the polymerisation was proposed.